EP4731987A1

EP4731987A1 - Corrosion/erosion sensor and corresponding operating method

Info

Publication number: EP4731987A1
Application number: EP24739980.1A
Authority: EP
Inventors: Brian L. Wardle; Luiz H. ACAUAN; Aniruddha Ghosh; Yosef Stein; Haim Primo
Original assignee: Analog Devices Inc; Massachusetts Institute of Technology
Current assignee: Analog Devices Inc; Massachusetts Institute of Technology
Priority date: 2023-06-21
Filing date: 2024-06-21
Publication date: 2026-04-29
Also published as: WO2024263875A1; CN121548735A

Abstract

The present disclosure is related to corrosion/erosion sensors, such as wireless corrosion/erosion sensors, and related systems and methods.

Description

CORROSION/EROSION SENSOR AND CORRESPONDING OPERATING METHOD

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63/509,515, filed June 21, 2023, and entitled “Corrosion/Erosion Sensors and Related Systems and Methods,” which is incorporated herein by reference in its entirety for all purposes.

TECHNICAL FIELD

Corrosion/erosion sensors, such as wireless corrosion/erosion sensors, and related systems and methods are generally described.

SUMMARY

The present disclosure is related to corrosion/erosion sensors, such as wireless corrosion/erosion sensors, and related systems and methods. The subject matter of the present disclosure involves, in some cases, interrelated products, alternative solutions to a particular problem, and/or a plurality of different uses of one or more systems and/or articles.

According to certain embodiments, a sensor system is described. In some embodiments, the sensor system comprises a single circuit comprising a first RLC circuit pathway and a second RLC circuit pathway, wherein at least a portion of the first RLC circuit pathway is configured to corrode and/or erode and the second RLC circuit pathway is configured as a reference circuit such that the circuit signal(s) can be used to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded.

According to some embodiments, a method for operating a sensor system is described. In certain embodiments, the method comprises measuring, with the sensor system, a first signal of a single circuit disposed in the sensor system, wherein the single circuit comprises a first RLC circuit pathway and a second RLC circuit pathway, wherein at least a portion of the first RLC circuit pathway is configured to corrode and/or erode and the second RLC circuit pathway is configured as a reference circuit such that the circuit signal(s) can be used, at least in part, to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded. In some embodiments, the method comprises measuring, with the sensor system, a second signal of the single circuit, wherein the second signal is a reference signal of the reference circuit. In certain embodiments, the method comprises determining, with a processor, whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded based at least in part on a comparison between the first signal and the second signal.

Other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments of the disclosure when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and/or inconsistent disclosure, the present specification shall control.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the present disclosure will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale unless otherwise indicated. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the disclosure shown where illustration is not necessary to allow those of ordinary skill in the art to understand the disclosure.

FIG. 1 A is a top-view schematic illustration of a circuit comprising a first RLC circuit pathway and a second RLC circuit pathway, wherein the first RLC circuit pathway comprises an inductor and a first capacitor electronically coupled to the inductor, and the second RLC circuit pathway comprises the inductor and a second capacitor electronically coupled to the inductor.

FIG. IB is a top-view schematic illustration of the circuit of FIG. 1 A, wherein the first RLC circuit pathway is represented as a dotted line.

FIG. 1C is a top-view schematic illustration of the circuit of FIG. 1 A, wherein the second RLC circuit pathway is represented as a dotted line. FIG. ID is a top-view schematic illustration of a circuit comprising a first RLC circuit pathway and a second RLC circuit pathway, wherein the first RLC circuit pathway comprises a first inductor and a first capacitor electronically coupled to the first inductor, and the second RLC circuit pathway comprises a second inductor and a second capacitor electronically coupled to the second inductor.

FIG. IE is a top-view schematic illustration of the circuit of FIG. ID, wherein the first RLC circuit pathway is represented as a dotted line.

FIG. IF is a top-view schematic illustration of the circuit of FIG. ID, wherein the second RLC circuit pathway is represented as a dotted line.

FIG. 2 is a diagram of a RLC circuit pathway, in accordance with certain embodiments.

FIG. 3 A is a schematic illustration of the fabrication of an inductor in which electronically conductive nanostructures are used to form the electronically conductive pathway of the inductor, in accordance with certain embodiments.

FIG. 3B is a schematic illustration of the fabrication of an interdigitated capacitor in which electronically conductive nanostructures are used to form the electrodes of the interdigitated capacitor, in accordance with certain embodiments.

FIGS. 4A-4D are a series of cross-sectional schematic illustrations showing the fabrication of a parallel-plate capacitor in which electronically conductive nanostructures are used to form the electrodes of the parallel-plate capacitor, in accordance with certain embodiments.

FIG. 5 is a block diagram showing an exemplary sensor system, in accordance with certain embodiments.

FIG. 6 is a schematic illustration showing the measurement of a resonant frequency of a sensor, in accordance with some embodiments.

FIG. 7 shows, according to some embodiments, a comparison of a resonance frequency of a first signal of a single circuit and a resonance frequency of a second signal of a single circuit.

DETAILED DESCRIPTION

Corrosion/erosion sensors (e.g., wireless corrosion/erosion sensors), and related systems and methods, are generally described. In accordance with certain embodiments, the sensors comprise a single circuit comprising a first RLC circuit pathway and a second RLC circuit pathway. The first RLC circuit pathway can comprise an inductor and a first capacitor electronically coupled to the inductor, and the second circuit pathway can comprise the inductor and a second capacitor electronically coupled to the inductor.

In accordance with certain embodiments, at least a portion of the first RLC circuit pathway is configured to corrode and/or erode and the second RLC circuit pathway is configured as a reference circuit such that one can determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or determine the degree to which the first RLC circuit pathway has corroded and/or eroded. In some embodiments, for example, a coating disposed on a portion of the inductor in the first RLC circuit pathway may corrode and/or erode, therefore changing the return signal of the first RLC circuit pathway. The second RLC circuit pathway, which does not comprise a coating, may have an unchanging return signal that is used as a reference signal and compared to the return signal of the first RLC circuit pathway. Configuring the sensor in this manner allows one to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the first RLC circuit pathway has corroded and/or eroded.

In certain embodiments, the sensors may be disposed in a sensor system that is configured to measure the return signal of the first RLC circuit pathway and the return signal of the second RLC circuit pathway. The sensor system may, in some embodiments, comprise a processor configured to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded based at least in part on a comparison between the return signal of the first RLC circuit pathway and the return signal of the second RLC circuit pathway. Suitable signals of the circuit that may be analyzed by the processor include, for example, a resonance frequency and/or a quality factor.

In some embodiments, the electrically conductive sensor elements (e.g., the electronic pathway of the inductor, the electrodes of the capacitor, etc.) comprise nanocomposites (e.g., formed by arranging electronically conductive elongated nanostructures within a conductive or non-conductive matrix material). Certain of the circuit arrangements described herein can be used as wireless sensors. For example, the circuits can be used, in some embodiments, as RLC resonators. In some embodiments, one can wirelessly interrogate a RLC resonator to determine whether the return signal of the first RLC circuit pathway has changed as compared to the return signal of the second RLC circuit pathway, an indication that a portion of the first RLC circuit pathway has corroded and/or eroded. As mentioned above, for example, in some embodiments, when a portion of the first RLC circuit pathway corrodes and/or erodes, the return signal of the first RLC circuit pathway changes. In some embodiments, the return signal of the first RLC circuit pathway is compared to the return signal of the second RLC circuit pathway to determine, at least in part, whether the portion of the first RLC circuit pathway has corroded and/or eroded. The presence of the reference signal can aid in distinguishing changes in the return signal of the first RLC circuit pathway that may be due to factors other than corrosion/erosion of the first RLC circuit pathway (e.g., presence of structural defects such as cracks, mechanical strain, etc.) from changes in the return signal of the first RLC circuit pathway that are due to corrosion/erosion of the first RLC circuit pathway. Advantageously, in some embodiments, the sensor systems described herein can detect corrosion and/or erosion while avoiding issues associated with the circuit malfunctioning due to the corrosion and/or erosion.

In some embodiments, the circuit can be an oscillator. The circuit can be wirelessly interrogated, in some embodiments, and a return signal of the first RLC circuit pathway and a return signal of the second RLC circuit pathway can be generated by the circuit. The return signal of the first RLC circuit pathway and the return signal of the second RLC circuit pathway can be detected and analyzed by a processor to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded.

In some embodiments, the single circuit may be positioned on a target material of which one wishes to monitor structural health. Examples of suitable target materials include, but are not limited to, a component of a land system and/or vehicle, a water system and/or vehicle, an air system and/or vehicle, and/or a space system and/or vehicle. In some embodiments, the target material is a component of an airplane, a boat, a motor vehicle (e.g., motorcycle, car, truck, bus, and the like), a space vehicle (e.g., a rocket, and the like), a component of a building (e.g., a beam, a steel component, a concrete component, and the like), and the like.

In certain embodiments, the single circuit comprises a first RLC circuit pathway. FIG. 1 A is a top-view schematic illustration of circuit 100a comprising a first RLC circuit pathway, in accordance with certain embodiments. As shown in FIG. 1 A, the first RLC circuit pathway comprises first portion 128 of inductor 106 and first capacitor 108a electronically coupled to first portion 128 of inductor 106 via electronically conductive pathways 114a and 114b. Electronically conductive pathways 114a and 114b may, in some embodiments, comprise metal, carbon, or any other suitable electronically conductive material.

Inductor 106 can assume any of a variety of suitable configurations. In the embodiment illustrated in FIG. 1 A, inductor 106 comprises an electronically conductive pathway arranged in a spiral shape. Other inductor shapes and/or configurations are also possible.

As described herein in greater detail, in some embodiments, the inductor can comprise electronically conductive nanostructures (e.g., electronically conductive elongated nanostructures, such as carbon nanotubes) embedded within a conductive or non-conductive (e.g., electrically insulating) matrix. In certain embodiments, the electronically conductive nanostructures serve an electronic function of the inductor.

According to certain embodiments, a portion of the inductor may comprise a coating. For example, first portion 128 of inductor 106 may comprise a coating. In some embodiments wherein the inductor comprises electronically conductive elongated nanostructures, the coating is disposed on the electronically conductive elongated nanostructures.

Any of a variety of suitable coatings may be employed. In some embodiments, the coating comprises an electronically conductive material. For example, in certain embodiments, the coating comprises a metal. Suitable metals include, in some embodiments, iron (Fe), silver (Ag), stainless steel (SS), and/or combinations thereof. In certain embodiments, a coating comprising Fe and/or SS may be used to detect corrosion. In some embodiments, a coating comprising Ag may be used to detect erosion. Other coatings and/or metals are also possible. As explained in further detail herein, the coating may be configured to corrode and/or erode. The coating may have any of a variety of suitable thicknesses. In certain embodiments, for example, the coating has a thickness of greater than or equal to 1 nm, greater than or equal to 10 nm, greater than or equal to 100 nm, greater than or equal to 1 micrometer, or greater than or equal to 10 micrometers. In some embodiments, the coating has a thickness of less than or equal to 100 micrometers, less than or equal to 10 micrometers, less than or equal to 1 micrometer, less than or equal to 100 nm, or less than or equal to 10 nm. Combinations of the above recited ranges are possible (e.g., the coating has a thickness of greater than or equal to 1 nm and less than or equal to 100 micrometers, the coating has a thickness of greater than or equal to 100 nm and less than or equal to 1 micrometer). Other ranges are also possible.

The inductor may have any of a variety of suitable dimensions. Referring to FIG. 1A, for example, inductor 106 has first dimension 120 and second dimension 122, wherein second dimension 122 is perpendicular to first dimension 120.

The first dimension of the inductor may be any of a variety of suitable values. In certain embodiments, for example, the first dimension of the inductor is greater than or equal to 10 micrometers, greater than or equal to 100 micrometers, greater than or equal to 1 millimeter, greater than or equal to 1 centimeter, or greater than or equal to 10 centimeters. In some embodiments, the first dimension of the inductor is less than or equal to 1 meter, less than or equal to 10 centimeters, less than or equal to 1 centimeter, less than or equal to 1 millimeter, or less than or equal to 100 micrometers. Combinations of the above recited ranges are possible (e.g., the first dimension of the inductor is greater than or equal to 10 micrometers and less than or equal to 1 meter, the first dimension of the inductor is greater than or equal to 1 millimeter and less than or equal to 1 centimeter). Other ranges are also possible.

The second dimension of the inductor (e.g., perpendicular to the first dimension of the inductor) may be any of a variety of suitable values. According to some embodiments, for example, the second dimension of the inductor is greater than or equal to 10 micrometers, greater than or equal to 100 micrometers, greater than or equal to 1 millimeter, greater than or equal to 1 centimeter, or greater than or equal to 10 centimeters. In certain embodiments, the second dimension of the inductor is less than or equal to 1 meter, less than or equal to 10 centimeters, less than or equal to 1 centimeter, less than or equal to 1 millimeter, or less than or equal to 100 micrometers. Combinations of the above recited ranges are possible (e.g., the second dimension of the inductor is greater than or equal to 10 micrometers and less than or equal to 1 meter, the second dimension of the inductor is greater than or equal to 1 millimeter and less than or equal to 1 centimeter). Other ranges are also possible.

First capacitor 108a can assume any of a variety of suitable configurations. In some embodiments, first capacitor 108a is an interdigitated capacitor comprising a first electrode and a second electrode. In other embodiments, first capacitor 108a is a parallel-plate capacitor (e.g., a circular-shaped parallel-plate capacitor, a square-shaped parallel-plate capacitor, and the like). In certain embodiments, the parallel-plate capacitor comprises a first electrode, a second electrode, and a conductive or non- conductive material between the first electrode and the second electrode. Examples of conductive materials for use within the parallel-plate capacitor include, but are not limited to, conductive polymers, metals, or combinations thereof. Examples of non- conductive materials for use within the parallel-plate capacitor include, but are not limited to, polymers (e.g., epoxy resin (e.g., EPON resin), paramethylstyrene (PMS), para-methoxyamphetamine (PMA), polyimide (e.g., Kapton®), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), bis-maleimide (BMI), cyanate ester, and the like), metal and/or metalloid oxides, glasses, ceramics, or any combinations of two or more of these materials.

As described herein in greater detail, in certain embodiments, the first capacitor can comprise electronically conductive nanostructures (e.g., electronically conductive elongated nanostructures, such as carbon nanotubes) embedded within a conductive or non-conductive (e.g., electrically insulating) matrix. In some embodiments, the electronically conductive nanostructures serve an electronic function of the first capacitor.

In the embodiment shown in FIG. 1 A, inductor 106 is electronically coupled to first capacitor 108a. In particular, first electrode 116a of first capacitor 108a may be electronically coupled to second end 126 of inductor 106 via electronically conductive pathway 114a, and second electrode 118a of first capacitor 108a may be electronically coupled to first portion 128 of inductor 106 via electronically conductive pathway 114b.

According to some embodiments, when inductor 106 is electronically coupled to first capacitor 108a, then inductor 106 and first capacitor 108a can form a RLC circuit pathway (e.g., a first RLC circuit pathway), such as the RLC circuit pathway illustrated in FIG. 2. In some embodiments, a dedicated resistor can be incorporated into the RLC circuit pathway. In other embodiments, the intrinsic electrical resistivity of the circuit elements and/or the electronically conductive pathways coupling the circuit elements to each other can serve as the resistor of the RLC circuit pathway.

FIG. IB is a top-view schematic illustration of circuit 100a, wherein the first RLC circuit pathway is represented in dotted line. As shown in FIG. IB, the first RLC circuit pathway comprises, in certain embodiments, an electronically conductive pathway from first electrode 116a of first capacitor 108a, through electronically conductive pathway 114a, through second end 126 of inductor 106, through first portion 128 of inductor 106 (e.g., the portion of inductor 106 shown in dotted line in FIG. IB), through electronically conductive pathway 114b, and to second electrode 118a of first capacitor 108a.

As described herein in greater detail, first portion 128 of inductor 106 (e.g., the portion of inductor 106 shown in dotted line in FIG. IB) may comprise a coating (e.g., an electronically conductive coating, such as a metal).

In some embodiments, the first RLC circuit pathway may be configured to produce a return signal. In certain embodiments, for example, the circuit may be a resonator and the first RLC circuit pathway may produce a return signal in response to a suitable input signal. Any of a variety of suitable input signals may be utilized. In some embodiments, for example, the sensor system is a wireless sensor system and the input signal comprises electromagnetic radiation. In other embodiments, the sensor system is a wired sensor system and the input signal comprises power (e.g., voltage, current) from a power supply. As described herein in greater detail, the return signal of the first RLC circuit pathway may be transmitted to and analyzed by a processor.

In certain embodiments, circuit 100a comprises a second RLC circuit pathway. FIG. 1C is a top-view schematic illustration of circuit 100a, wherein the second RLC circuit pathway is represented in dotted line. Referring to FIG. 1C, the second RLC circuit pathway comprises second portion 130 of inductor 106 and second capacitor 108b electronically coupled to second portion 130 of inductor 106 via electronically conductive pathways 114b and 114c. Electronically conductive pathways 114b and 114c may, in some embodiments, comprise metal, carbon, or any other suitable electronically conductive material.

According to certain embodiments, second portion 130 of inductor 106 (e.g., the portion of inductor 106 shown in dotted line in FIG. 1C) does not comprise a coating.

Second capacitor 108b can assume any of a variety of suitable configurations. In some embodiments, second capacitor 108b is an interdigitated capacitor comprising a first electrode and a second electrode. In other embodiments, second capacitor 108b is a parallel-plate capacitor (e.g., a circular-shaped parallel-plate capacitor, a square-shaped parallel-plate capacitor, etc.). In certain embodiments, the parallel-plate capacitor comprises a first electrode, a second electrode, and a conductive or non-conductive material between the first electrode and the second electrode. Examples of conductive materials for use within the parallel-plate capacitor include, but are not limited to, conductive polymers, metals, or combinations thereof. Examples of non-conductive materials for use within the parallel-plate capacitor include, but are not limited to, polymers (e.g., epoxy resin (e.g., EPON resin), paramethylstyrene (PMS), paramethoxyamphetamine (PMA), polyimide (e.g., Kapton®), poly ether ether ketone (PEEK), polyether ketone ketone (PEKK), bis-maleimide (BMI), cyanate ester, and the like), metal and/or metalloid oxides, glasses, ceramics, or any combinations of two or more of these materials.

As described herein in greater detail, in certain embodiments, the second capacitor can comprise electronically conductive nanostructures (e.g., electronically conductive elongated nanostructures, such as carbon nanotubes) embedded within a conductive or non-conductive (e.g., electrically insulating) matrix. In some embodiments, the electronically conductive nanostructures serve an electronic function of the second capacitor.

In the embodiment shown in FIG. 1C, inductor 106 is electronically coupled to second capacitor 108b. In particular, first electrode 116b of second capacitor 108b may be electronically coupled to second portion 130 of inductor 106 via electronically conductive pathway 114b, and second electrode 118b of second capacitor 108b may be electronically coupled to first end 124 of inductor 106 via electronically conductive pathway 114c. According to some embodiments, when inductor 106 is electronically coupled to second capacitor 108b, then inductor 106 and second capacitor 108b can form a RLC circuit pathway (e.g., a second RLC circuit pathway), such as the RLC circuit pathway illustrated in FIG. 2. In some embodiments, a dedicated resistor can be incorporated into the RLC circuit pathway. In other embodiments, the intrinsic electrical resistivity of the circuit elements and/or the electronically conductive pathways coupling the circuit elements to each other can serve as the resistor of the RLC circuit pathway.

As shown in FIG. 1C, the second RLC circuit pathway comprises, in some embodiments, an electronically conductive pathway from first electrode 116b of second capacitor 108b, through electronically conductive pathway 114b, through second portion 130 of inductor 106 (e.g., the portion of inductor 106 shown in dotted line in FIG. 1C), through first end 124 of inductor 106, through electronically conductive pathway 114c, and to second electrode 118b of capacitor 108b.

In certain embodiments, the first RLC circuit pathway and the second RLC circuit pathway are RLC circuit pathways associated with a single inductor. Referring, for example, to FIGS. 1B-1C, the first RLC circuit pathway (shown, e.g., in FIG. IB) and the second RLC circuit pathway (shown, e.g., in FIG. 1C) are both associated with inductor 106. In other embodiments (e.g., as shown in FIG. 1D-1F) separate inductors (e.g., inductors arranged in a side-by-side fashion) can be used.

According to certain embodiments, different capacitors are used in each of the first RLC circuit pathway and the second RLC circuit pathway. Referring to FIGS. 1B- 1C, for example, first capacitor 108a is used in the first RLC circuit pathway and second capacitor 108b is used in the second RLC circuit pathway. In some embodiments, different portions of the same inductor are used in the first RLC circuit pathway and the second RLC circuit pathway. Referring to FIGS. 1B-1C, for example, first portion 128 of inductor 106 is used in the first RLC circuit pathway, and second portion 130 of inductor 106 is used in the second RLC circuit pathway.

According to some embodiments, as shown in FIGS. 1B-1C, at least a portion of the second RLC circuit pathway may overlap with at least a portion of the first RLC circuit pathway. In certain embodiments, for example, the second RLC circuit pathway comprises electronically conductive pathway 114b that overlaps with the first RLC circuit pathway. As explained in greater detail herein, the second RLC circuit pathway may be configured to produce a return signal, in accordance with certain embodiments. In certain embodiments, for example, the circuit may be a resonator and the second RLC circuit pathway may produce a return signal in response to a suitable input signal. Any of a variety of suitable input signals may be utilized. In some embodiments, for example, the sensor system is a wireless sensor system and the input signal comprises electromagnetic radiation. In other embodiments, the sensor system is a wired sensor system and the input signal comprises power (e.g., voltage, current) from a power supply. The return signal of the second RLC circuit pathway may, in some embodiments, be different than the return signal of the first RLC circuit pathway. As described herein in greater detail, the return signal of the second RLC circuit pathway may be transmitted to and analyzed by a processor.

In some embodiments, as described above, nanostructures can be incorporated into one or more elements of the circuit (e.g., into an inductor and/or a capacitor). In some embodiments, the nanostructures can serve an electronic function of the circuit components. For example, in some embodiments, the nanostructures are electronically conductive and can be embedded in a conductive or non-conductive matrix to impart electronic conductivity to the circuit element.

FIG. 3 A is a schematic illustration of the fabrication of an inductor in which electronically conductive nanostructures are used to form the electronically conductive pathway of the inductor, in accordance with certain embodiments. In certain embodiments, substrate 301a is provided, and patterned with active growth material 302a, such as a catalyst. The patterning may be performed, for example, using lithography masking techniques. According to some embodiments, a forest of vertically aligned patterned nanostructures 304a are grown on substrate 301a, followed by knocking down the forest of vertically aligned patterned nanostructures 304a (e.g., using a roller), drop-casting electrically insulating material 310a, and spin-coating 312a, thereby providing inductor 106 comprising forest of substantially parallel patterned nanostructures 304a embedded in electrically insulating material 310a (e.g., a structural polymer matrix).

FIG. 3B is a schematic illustration of the fabrication of an interdigitated capacitor in which electronically conductive nanostructures are used to form the electrodes of the capacitor, in accordance with certain embodiments. In certain embodiments, substrate 301b is provided, and patterned with active growth material 302b, such as a catalyst. The patterning may be performed, for example, using lithography masking techniques. According to some embodiments, a forest of vertically aligned patterned nanostructures 304b are grown on substrate 301b, followed by knocking down the forest of vertically aligned patterned nanostructures 304b (e.g., using a roller), drop-casting electrically insulating material 310b, and spin-coating 312b, thereby providing first electrode 116 and/or second electrode 118 of capacitor 108. In certain embodiments, first electrode 116 and/or second electrode 118 of capacitor 108 comprise forest of substantially parallel patterned nanostructures 304b embedded in electrically insulating material 310b (e.g., a structural polymer matrix).

FIGS. 4A-4D are a series of cross-sectional schematic illustrations showing the fabrication of a parallel-plate capacitor in which electronically conductive nanostructures are used to form the electrodes of the parallel-plate capacitor, in accordance with certain embodiments. In FIG. 4A, a collection of elongated nanostructures 401 has been formed on substrate 301c (e.g., a Kapton substrate), for example, using catalytic growth of carbon nanotubes. The collection of elongated nanostructures has been infused with a non-conductive material 402a (e.g., EPON). The elongated nanostructures can provide electrical conductivity, such that the combination of the elongated nanostructures 401 and non-conductive material 402a forms the first electrode of the parallel-plate capacitor. In FIG. 4B, additional non-conductive material 402b (e.g., EPON) has been placed over elongated nanostructures 401 and non-conductive material 402a. In FIG. 4C, non- conductive material 402b has been reformed in the shape of layer. In one non-limiting embodiment, non-conductive material 402b is a layer of Kapton film with epoxy (e.g., having a thickness of less than 50 micrometers, or less than 10 micrometers). In FIG. 4D, a second electrode comprising electronically conductive elongated nanostructures 401 embedded in non-conductive material layer 402c has been added to the top of the stack from FIG. 4C. Additional substrate 301d may also be included. Optionally, the stack may be cured, for example, using a hot press, to form the final parallel-plate capacitor. Optionally, substrate 301c and/or substrate 301d may be omitted or removed from the capacitor. Non-limiting examples of the use of electronically conductive nanostructures embedded in non-conductive matrices to form circuit components are described, for example, in International Patent Application Publication No. WO 2019/118706, published on June 20, 2019, filed on December 13, 2018, as International Application No. PCT/US2018/065422, and entitled “Structural Electronics Wireless Sensor Nodes” and in U.S. Patent Application No. 16/900,159, filed on June 12, 2020, published as U.S. Patent Publication No. 2020/0309674 on October 1, 2020, and entitled “Structural Electronics Wireless Sensor Nodes,” each of which is incorporated herein by reference in its entirety for all purposes.

Any of a variety of suitable nanostructures can be used in association with the embodiments described herein. The term “nanostructure” is used herein in a manner consistent with its ordinary meaning in the art and refers to a structure that has a characteristic dimension, such as a cross-sectional diameter, or other appropriate dimension, that is greater than or equal to 1 nm and less than 1 micrometer. In some embodiments, the nanostructure has at least one characteristic dimension of less than 750 nm, less than 500 nm, less than 250 nm, less than 100 nm, less than 75 nm, less than 50 nm, less than 25 nm, less than 10 nm, or, in some cases, less than 5 nm.

In some embodiments, the nanostructures are elongated nanostructures (e.g., having an aspect ratio of at least 10, and in some embodiments, at least 100; at least 1,000; at least 10,000; at least 100,000; or more). In some embodiments, the elongated nanostructure is a nanofiber, a nanowire, a nanorod, or the like. In certain aspects, the nanostructures are electrically conductive.

In certain embodiments, the nanostructures comprise carbon-based nanostructures (i.e., nanostructures that are at least 50 atomic percent (at%) carbon and, in some cases, can be at least 60 at%, at least 70 at%, at least 80 at%, at least 90 at%, at least 95 at%, at least 99 at%, or more carbon). In certain embodiments, the nanostructures comprise carbon nanotubes (CNTs). The term “carbon nanotube” is used herein in a manner consistent with its ordinary meaning in the art and refers to a substantially cylindrical molecule or nanostructure comprising a fused network of primarily six-membered rings (e.g., six-membered aromatic rings) comprising primarily carbon atoms. Further details regarding CNTs are described below. In some embodiments, the nanostructures comprise metal. In some embodiments the metal is a conducting metal. For example, the nanostructure may comprise silicon (Si), germanium (Ge), gold (Au), metal oxides (e.g., I Ch, SnCh, ZnO), and the like.

Additional examples of nanostructures that can be used include, but are not limited to, metal nanowires, conductive particles, buckyballs, graphene flakes, and the like.

In some embodiments, one or more circuit elements (e.g., the capacitor, the inductor) can comprise electronically conductive nanostructures embedded in a conductive or non-conductive matrix. Examples of conductive matrices include, but are not limited to, conductive polymers, metals, or combinations thereof. Example of non- conductive matrices include, but are not limited to, polymers (e.g., epoxy resin (e.g., EPON resin), paramethylstyrene (PMS), para-methoxyamphetamine (PMA), polyimide (e.g., Kapton®), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), bis- maleimide (BMI), cyanate ester, and the like), metal and/or metalloid oxides, glasses, ceramics, or any combinations of two or more of these materials.

According to certain embodiments, at least a portion of the first RLC circuit pathway is configured to corrode and/or erode. In some embodiments, for example, a portion of the inductor in the first RLC circuit pathway may comprise a coating that is configured to corrode and/or erode. Referring to FIG. IB, for example, some or all of first portion 128 of inductor 106 (e.g., corresponding to the portion of inductor 106 in the first RLC circuit pathway), shown in dotted line in FIG. IB, comprises a coating.

The sensor systems described herein may be disposed on or in proximity to a target material being monitored so that the coating experiences substantially the same conditions as the target material. Any of a variety of suitable target materials may be employed. In some embodiments, for example, the target material is a component of a land system and/or vehicle, a water system and/or vehicle, an air system and/or vehicle, and/or a space system and/or vehicle. In some embodiments, the target material is a component of an airplane, a boat, a motor vehicle (e.g., motorcycle, car, truck, bus, and the like), a space vehicle (e.g., a rocket and the like), a component of a building (e.g., a beam, a steel component, a concrete component, and the like), and the like.

In some embodiments, the coating may comprise a material that corrodes at a corrosion rate that is within 20% of a corrosion rate of the target material being monitored by the sensor system. For example, in certain embodiments, the coating comprises a material that corrodes at a corrosion rate that is within 20%, within 15%, within 10%, within 5%, or within 1% of a corrosion rate of the target material being monitored by the sensor system. According to some embodiments, the coating and the target material comprise the same material, such that the corrosion rate of the coating and the corrosion rate of the target material is the same.

The coating may corrode and/or erode when exposed to any of variety of suitable corrosion conditions. In certain embodiments, for example, the coating may corrode and/or erode when exposed to water (e.g., moisture, condensation, rain, etc.), oxygen, high temperatures, low temperatures, mechanical vibrations, and/or the like.

According to certain embodiments, the first RLC circuit pathway (e.g., the electronically conductive pathway from first electrode 116a of first capacitor 108a, through electronically conductive pathway 114a, through second end 126 of inductor 106, through first portion 128 of inductor 106 (e.g., the portion of inductor 106 shown in dotted line in FIG. IB), through electronically conductive pathway 114b, and to second electrode 118b of first capacitor 108a), shown in dotted line in FIG. IB, is configured to produce a return signal. The return signal of the first RLC circuit pathway may change, in some embodiments, as the coating disposed on the portion of the inductor (e.g., on some or all of first portion 128 of inductor) corrodes and/or erodes when exposed to one or more corrosion conditions. In some embodiments, for example, the return signal of the first RLC circuit pathway may change as the inductance of the circuit changes due to the coating disposed on the portion of the inductor corroding and/or eroding. In certain embodiments, as explained in further detail herein, the return signal of the first RLC circuit pathway, which may change due to corrosion and/or erosion, may be compared to the return signal of the second RLC circuit pathway, which does not change due to corrosion and/or erosion, to determine whether the portion of the inductor in the first RLC circuit pathway has corroded and/or eroded.

In certain embodiments, the second RLC circuit pathway is configured as a reference circuit to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded. In some embodiments, for example, no portion of the inductor in the second RLC circuit pathway comprises a coating. Referring to FIG. 1C, for example, none of second portion 130 of inductor 106 (e.g., corresponding to the portion of inductor 106 in the second RLC circuit pathway), shown in dotted line in FIG. 1C, comprises a coating.

According to some embodiments, the second RLC circuit pathway (e.g., the electronically conductive pathway from first electrode 116b of second capacitor 108b, through electronically conductive pathway 114b, through second portion 130 of inductor 106 (e.g., the portion of inductor 106 shown in dotted line in FIG. 1C), through first end 124 of inductor 106, through electronically conductive pathway 114c, and to second electrode 118b of capacitor 108b, shown in dotted line in FIG. 1C, is configured to produce a return signal. The return signal of the second RLC circuit pathway does not change, in certain embodiments, as the coating disposed on the portion of the inductor (e.g., on some or all of first portion 128 of inductor) corrodes and/or erodes when exposed to one or more corrosion conditions. In some embodiments, as explained in further detail herein, the return signal of the second RLC circuit pathway, which does not change due to corrosion and/or erosion, may be compared to the return signal of the first RLC circuit pathway, which may change due to corrosion and/or erosion, to determine whether the portion of the inductor in the first RLC circuit pathway has corroded and/or eroded.

According to some embodiments, the single circuit (e.g., comprising a first RLC circuit pathway and a second RLC circuit pathway) comprises a first inductor and a second inductor. FIG. ID is a top-view schematic illustration of circuit 100b comprising a first RLC circuit pathway and a second RLC circuit pathway, wherein the first RLC circuit pathway comprises first inductor 106a and first capacitor 108a’ electronically coupled to first inductor 106a, and the second RLC circuit pathway comprises second inductor 106b and second capacitor 108b’ electronically coupled second inductor 106b.

The first inductor (e.g., first inductor 106a) and the second inductor (e.g., second inductor 106b) may assume any of a variety of suitable configurations, as explained herein in greater detail with respect to inductor 106 of FIG. 1 A. In certain embodiments, for example, the first inductor and/or the second inductor comprise an electronically conductive pathway arranged in a spiral shape, although other inductor shapes and/or configurations are possible.

The first inductor (e.g., first inductor 106a) and/or the second inductor (e.g., second inductor 106b) may comprise electronically conductive nanostructures (e.g., electronically conductive elongated nanostructures, such as carbon nanotubes) embedded within a conductive or non-conductive (e.g., electrically insulating) matrix, as described herein in greater detail with respect to FIG. 3 A. In some embodiments, the electronically conductive nanostructures of the first inductor serve an electronic function of the first inductor. In certain embodiments, the electronically conductive nanostructures of the second inductor serve an electronic function of the second inductor.

In certain embodiments, at least a portion of the first inductor comprises a coating. Referring, for example, to FIG. ID, at least a portion of first inductor 106a comprises a coating. In certain embodiments wherein at least a portion of first inductor 106a comprises a coating, second inductor 106b does not comprise a coating.

Any of a variety of suitable coatings may be employed, as described herein in greater detail. In some embodiments, for example, the coating comprises a metal (e.g., Fe, Ag, SS, and the like).

The coating may have any of a variety of suitable thicknesses, as described herein in greater detail. In some embodiments, for example, the coating has a thickness of greater than or equal to 1 nm and less than or equal to 100 micrometers.

The first inductor and/or the second inductor may have any of a variety of suitable dimensions, as described herein in greater detail with respect to FIG. 1 A. In some embodiments, the first inductor and the second inductor have the same or substantially the same dimensions. In some embodiments, for example, the value of a first dimension of the first inductor is within 20% (or within 15%, within 10%, within 5%, within 1%, within 0.1%) of the value of the first dimension of the second inductor. In certain embodiments, the value of the second dimension of the first inductor is within 20% (or within 15%, within 10%, within 5%, within 1%, within 0.1%) of the value of the second dimension of the second inductor. In certain embodiments, configuring the first inductor and the second inductor such that they have the same or substantially the same dimensions advantageously allows one to accurately compare a return signal of the first RLC circuit pathway to the second RLC circuit pathway to determine, at least in part, whether the first RLC circuit pathway has corroded and/or eroded, as described herein in greater detail.

The first inductor and the second inductor may be positioned adjacent to each other (e.g., in a side-by-side fashion) such that the first inductor and the second inductor are separated by a distance. For example, referring to FIG. ID, first inductor 106a and second inductor 106b are positioned adjacent to each other such that outermost end 132a of first inductor 106a and outermost end 132b of second inductor 106b adjacent to outermost end 132a of first inductor 106a are separated by distance 130.

The first inductor and the second inductor may be separated by any a variety of suitable distances. In some embodiments, the shortest distance between the first inductor and the second inductor is less than or equal to 100 meters, less than or equal to 50 meters, less than or equal to 10 meters, less than or equal to 5 meters, less than or equal to 1 meter, less than or equal to 50 centimeters, less than or equal to 10 centimeters, less than or equal to 5 centimeters, less than or equal to 1 centimeter, less than or equal to 0.5 centimeters, less than or equal to 0.1 centimeters, less than or equal to 500 micrometers, less than or equal to 100 micrometers, less than or equal to 50 micrometers, less than or equal to 10 micrometers, less than or equal to 5 micrometers, less than or equal to 1 micrometer, less than or equal to 0.5 micrometers, less than or equal to 100 nanometers, less than or equal to 50 nanometers, less than or equal to 10 nanometers, less than or equal to 5 nanometers, or less. In certain embodiments, the shortest distance between the first inductor and the second inductor is greater than or equal to 1 nanometer, greater than or equal to 5 nanometers, greater than or equal to 10 nanometers, greater than or equal to 50 nanometers, greater than or equal to 100 nanometers, greater than or equal to 0.5 micrometers, greater than or equal to 1 micrometer, greater than or equal to 5 micrometers, greater than or equal to 10 micrometers, greater than or equal to 50 micrometers, greater than or equal to 100 micrometers, greater than or equal to 500 micrometers, greater than or equal to 0.1 centimeters, greater than or equal to 0.5 centimeters, greater than or equal to 1 centimeter, greater than or equal to 5 centimeters, greater than or equal to 10 centimeters, greater than or equal to 50 centimeters, greater than or equal to 1 meter, greater than or equal to 5 meters, greater than or equal to 10 meters, greater than or equal to 50 meters, or greater. Combinations of the above recited ranges are possible (e.g., the distance between the first inductor and the second inductor is less than or equal to 100 meters and greater than or equal to 1 nanometer, the distance between the first inductor and the second inductor is less than or equal to 0.1 centimeters and greater than or equal to 500 micrometers). Other ranges are also possible. In certain embodiments, configuring the first inductor and the second inductor such that they are separated by a minimal distance advantageously allows one to accurately compare a return signal of the first RLC circuit pathway to the second RLC circuit pathway to determine, at least in part, whether the first RLC circuit pathway has corroded and/or eroded, as described herein in greater detail. In some embodiments, for example, having a minimal distance between the first inductor and the second inductor may ensure that the first inductor and the second inductor are exposed to the same or substantially the same environment such that the return signal of the first RLC circuit pathway can be accurately compared to the return signal of the second RLC circuit pathway to determine, at least in part, whether the first RLC circuit pathway has corroded and/or eroded.

Referring to FIG. ID, first capacitor 108a’ can assume any of a variety of suitable configurations, as described herein in greater detail with respect to FIG. 1 A. For example, in some embodiments, first capacitor 108a’ is an interdigitated capacitor comprising a first electrode and a second electrode. In other embodiments, first capacitor 108a’ is a parallel-plate capacitor comprising a first electrode, a second electrode, and a conductive or non-conductive material between the first electrode and the second electrode.

In some embodiments, first capacitor 108a’ comprises electronically conductive nanostructures (e.g., electronically conductive elongated nanostructures, such as carbon nanotubes) embedded within a conductive or non-conductive (e.g., electrically insulating) matrix, as described herein in greater detail with respect to FIGS. 3B-4D. In some embodiments, the electronically conductive nanostructures of first capacitor 108a’ serve an electronic function of first capacitor 108a'.

According to some embodiments, as shown in FIG. ID, first inductor 106a is electronically coupled to first capacitor 108a’. In particular, first electrode 116a’ of first capacitor 108a’ may be electronically coupled to second end 126’ of first inductor 106a via electronically conductive pathway 114a’, and second electrode 118a’ of first capacitor 108a’ may be electronically coupled to first end 124a’ of first inductor 106a via electronically conductive pathway 114b’. As described herein in greater detail, electronically conductive pathways 114a’ and 114b’ may, in certain embodiments, comprise metal, carbon, or any other suitable electronically conductive material. In certain embodiments, when first inductor 106a is electronically coupled to first capacitor 108a’, then first inductor 106a and first capacitor 108a’ can form a RLC circuit pathway (e.g., a first RLC circuit pathway), such as the RLC circuit pathway illustrated in FIG. 2. In some embodiments, a dedicated resistor can be incorporated into the RLC circuit pathway. In other embodiments, the intrinsic electrical resistivity of the circuit elements and/or the electronically conductive pathways coupling the circuit elements to each other can serve as the resistor of the RLC circuit pathway.

Referring to FIG. ID, second capacitor 108b’ can assume any of a variety of suitable configurations, as described herein in greater detail with respect to FIG. 1 A. For example, in some embodiments, second capacitor 108b’ is an interdigitated capacitor comprising a first electrode and a second electrode. In other embodiments, second capacitor 108b’ is a parallel-plate capacitor comprising a first electrode, a second electrode, and a conductive or non-conductive material between the first electrode and the second electrode.

In some embodiments, second capacitor 108b’ comprises electronically conductive nanostructures (e.g., electronically conductive elongated nanostructures, such as carbon nanotubes) embedded within a conductive or non-conductive (e.g., electrically insulating) matrix, as described herein in greater detail with respect to FIGS. 3B-4D. In some embodiments, the electronically conductive nanostructures of second capacitor 108b’ serve an electronic function of second capacitor 108b'.

According to some embodiments, as shown in FIG. ID, second inductor 106 is electronically coupled to second capacitor 108b’. In particular, second electrode 118b’ of second capacitor 108b’ may be electronically coupled to first end 124a” of second inductor 106b via electronically conductive pathway 114c’. In certain embodiments, as shown in FIG. ID, first inductor 106a is electronically coupled to second capacitor 108b’. In particular, first electrode 116b’ of second capacitor 108b’ may be electronically coupled to first end 124’ of first inductor 106a via electronically conductive pathway 114b’. As described herein in greater detail, electronically conductive pathways 114b’ and 114c’ may, in certain embodiments, comprise metal, carbon, or any other suitable electronically conductive material. In some embodiments, as shown in FIG. ID, first inductor 106a is electronically coupled to second inductor 106b. In particular, first end 124’ of first inductor 106a may be electronically coupled to second end 126” of second inductor 106b via electronically conductive pathway 114d. In certain embodiments, electronically conductive pathway 114d comprises metal, carbon, or any other suitable electronically conductive material. It should be understood that, while electronically conductive pathway 114b’ is shown in FIGS. 1D-1F as overlapping parts of inductor 106a, electronically conductive pathway 114b’ is, in accordance with certain embodiments, only in contact with first end 124’ of inductor 106a and not in contact with the other portions of inductor 106a that it overlaps in these figures. Similarly, while electronically conductive pathway 114c’ is shown in FIGS. 1D- 1F as overlapping parts of inductor 106b, electronically conductive pathway 114c’ is, in accordance with certain embodiments, only in contact with first end 124” of inductor 106b and not in contact with the other portions of inductor 106b that it overlaps in these figures.

In certain embodiments, when first inductor 106a and second inductor 106b are electronically coupled to second capacitor 108b’, and when first inductor 106a is electronically coupled to second inductor 106b, then second inductor 106b and second capacitor 108b’ can form a RLC circuit pathway (e.g., a second RLC circuit pathway), such as the RLC circuit pathway illustrated in FIG. 2. In some embodiments, a dedicated resistor can be incorporated into the RLC circuit pathway. In other embodiments, the intrinsic electrical resistivity of the circuit elements and/or the electronically conductive pathways coupling the circuit elements to each other can serve as the resistor of the RLC circuit pathway.

In some embodiments, as described herein in greater detail, circuit 100b comprises a first RLC circuit pathway. FIG. IE is a top-view schematic illustration of circuit 100b, wherein the first RLC circuit pathway is represented as a dotted line. In some embodiments, referring to FIG. IE, the first RLC circuit pathway comprises first inductor 106a and first capacitor 108a’ electronically coupled to first inductor 106a via electronically conductive pathways 114a’ and 114b’. As shown in FIG. IE, the first RLC circuit pathway comprises, in certain embodiments, an electronically conductive pathway from first electrode 116a’ of first capacitor 108a’, through electronically conductive pathway 114a’, through second end 126’ of first inductor 106a, through first inductor 106a, through first end 124’ of first inductor 106a, through electronically conductive pathway 114b’, and to second electrode 118a’ of first capacitor 108a’. In some embodiments, the first RLC circuit pathway may be configured to produce a return signal, as described herein in greater detail.

According to some embodiments, as described herein in greater detail, circuit 100b comprises a second RLC circuit pathway. FIG. IF is a top-view schematic illustration of circuit 100b, wherein the second RLC circuit pathway is represented as a dotted line. Referring to FIG. IF, the second RLC circuit pathway comprises second inductor 106b and second capacitor 108b’ electronically coupled to second inductor 106b via electronically conductive pathways 114b’, 114c’, and 114d. As shown in FIG. IF, the second RLC circuit pathway comprises, in some embodiments, an electronically conductive pathway from first electrode 116b’ of second capacitor 108b’, through electronically conductive pathway 114b’, through first end 124’ of first inductor 106a, through electronically conductive pathway 114d, through second end 126” of second inductor 106b, through second inductor 106b, through first end 124” of second inductor 106b, through electronically conductive pathway 114c’, and to second electrode 118b’ of second capacitor 108b’.

In certain embodiments, the second RLC circuit pathway may be configured to produce a return signal, as described herein in greater detail.

According to some embodiments, as described herein in greater detail, different capacitors are used in each of the first RLC circuit pathway and the second RLC circuit pathway. Referring to FIGS. 1E-1F, for example, first capacitor 108a’ is used in the first RLC circuit pathway and second capacitor 108b’ is used in the second RLC circuit pathway. In certain embodiments, different inductors are used in each of the first RLC circuit pathway and the second RLC circuit pathway. For example, referring to FIGS. 1E-1F, first inductor 106a is used in the first RLC circuit pathway and second inductor 106b is used in the second RLC circuit pathway.

In certain embodiments wherein at least a portion of first inductor 106a comprises a coating, at least a portion of the first RLC circuit pathway, shown in dotted line in FIG. IE, is configured to corrode and/or erode. For example, in certain embodiments, at least a portion of the coating disposed on at least a portion of first inductor 106a is configured to corrode and/or erode. According to some embodiments, the return signal of the first RLC circuit pathway may change as at least the portion of the coating disposed on at least the portion of first inductor 106a corrodes and/or erodes when exposed to one or more corrosion conditions. In some embodiments, for example, the return signal of the first RLC circuit pathway changes as the inductance of circuit 100b changes due to at least the portion of the coating disposed on at least the portion of first inductor 106a corroding and/or eroding. As described herein in greater detail, the return signal of the first RLC circuit pathway, which may change due to corrosion and/or erosion, may be compared to the return signal of the second RLC circuit pathway, which does not change due to corrosion and/or erosion, to determine whether the portion of first inductor 106a (e.g., at least a portion of the coating disposed on at least a portion of first inductor 106a) in the first RLC circuit pathway has corroded and/or eroded.

According to some embodiments, the second RLC circuit pathway, shown in dotted line in FIG. IF, is configured as a reference circuit to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded. For example, in some embodiments, no portion of second inductor 106b comprises a coating. In certain embodiments, the return signal of the second RLC circuit pathway does not change as at least the portion of the coating disposed on at least the portion of first inductor 106a corrodes and/or erodes when exposed to one or more corrosion conditions. In some embodiments, as explained in further detail herein, the return signal of the second RLC circuit pathway, which does not change due to corrosion and/or erosion, may be compared to the return signal of the first RLC circuit pathway, which may change due to corrosion and/or erosion, to determine whether the portion of first inductor 106a (e.g., at least a portion of the coating disposed on at least a portion of first inductor 106a) in the first RLC circuit pathway has corroded and/or eroded.

According to certain embodiments, the circuits described herein may be disposed in a sensor system. FIG. 5 is a block diagram showing an exemplary sensor system 500, in accordance with certain embodiments. As shown in FIG. 5, sensor system 500 comprises single circuit 100.

In some embodiments, sensor system 500 is configured to measure one or more first signals of single circuit 100 (e.g., one or more return signals of the first RLC circuit pathway of the single circuit) and one or more second signals of single circuit 100 (e.g., one or more return signals of the second RLC circuit pathway of the single circuit). The one or more first signals and/or the one or more second signals of the single circuit may, in some embodiments, be oscillating signals of the single circuit. In some embodiments, sensor system 500 comprises an optional energy storage module 502. Energy storage module 502 is, in certain embodiments, a power supply that provides power to at least some components of sensor system 500. In some embodiments, energy storage module 502 may be connected to an external power supply (not shown in FIG. 5) that provides a suitable power supply (e.g., a voltage and/or current) for operation of sensor system 500, although such an external power connection is not required. Energy storage module 502 may be included in some embodiments wherein the sensor system is a wired sensor system. In certain embodiments wherein the sensor system is a wireless sensor system, energy storage module 502 may not be included in sensor system 500.

According to certain embodiments, energy storage module 502 is configured to store electrical energy and to provide power to at least a portion of the circuit. In one embodiment, energy storage module 502 may comprise a battery or capacitor for storing energy. In another embodiment, energy storage module 502 may additionally comprise one or more energy harvesters (not shown in FIG. 5) to recharge a battery or capacitor, such that the sensor system 500 can operate for a prolonged period of time without the need to be connected to an external power source such as a power outlet to recharge the battery or capacitor inside the energy storage module 502. The energy harvester may be a mechanical harvester that converts mechanical-acoustic energy such as vibration or human motion into electricity, a thermoelectric harvester that converts temperature gradient such as temperature difference between different parts of the sensor system 800 into electricity, a solar energy or photovoltaic harvester that converts ambient light into electricity, and/or an electrochemical energy harvester that converts electrochemical potential differences in the system environment into electricity.

In some embodiments, sensor system 500 comprises processor 504. The processor may be configured, in certain embodiments, to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded based at least in part on a comparison between the one or more first signals of the single circuit and the one or more second signals of the single circuit. Examples of processors that could be used include, for example, commercially available processors such as one of the series x86; Celeron, Pentium, and Core processors, available from Intel; similar devices from AMD and Cyrix; the 680X0 series microprocessors available from Motorola; and the PowerPC microprocessor from IBM. Many other processors are also available.

Any suitable communication protocol may be used for processor 504 to communicate with circuit 100. In some embodiments, for example, processor 504 may receive the one or more first signals of the single circuit and/or the one or more second signals of the single circuit from wireless communication module 506. In other embodiments, processor 504 may be a local processor attached to circuit 100. In yet other embodiments, processor 504 may be based on the cloud and communicate with circuit 100 using a wired or wireless interface.

In certain embodiments, the comparison between the one or more first signals of the single circuit and the one or more second signals of the single circuit (e.g., the one or more reference signals of the reference circuit) comprises a comparison between a resonance frequency of the one or more first signals and a resonance frequency of the one or more second signals.

The resonance frequency of the one or more first signals of the single circuit may be any of a variety of suitable frequencies. In certain embodiments, for example, the resonance frequency of the one or more first signals is greater than or equal to 10 Hz, greater than or equal to 100 Hz, greater than or equal to 1 kHz, greater than or equal to 10 kHz, greater than or equal to 100 kHz, greater than or equal to 1 MHz, or greater than or equal to 10 MHz. In some embodiments, the resonance frequency of the one or more first signals is less than or equal to 100 MHz, less than or equal to 10 MHz, less than or equal to 1 MHz, less than or equal to 100 kHz, less than or equal to 10 kHz, less than or equal to 1 kHz, or less than or equal to 100 Hz. Combinations of the above recited ranges are also possible (e.g., the resonance frequency of the one or more first signals is greater than or equal to 10 Hz and less than or equal to 10 MHz, the resonance frequency of the one or more first signals is greater than or equal to 10 kHz and less than or equal to 100 MHz). Other ranges are also possible.

The resonance frequency of the one or more second signals of the single circuit (e.g., the one or more reference signals of the reference circuit) may be any of a variety of suitable frequencies. In certain embodiments, for example, the resonance frequency of the one or more second signals is greater than or equal to 10 Hz, greater than or equal to 100 Hz, greater than or equal to 1 kHz, greater than or equal to 10 kHz, greater than or equal to 100 kHz, greater than or equal to 1 MHz, or greater than or equal to 10 MHz. In some embodiments, the resonance frequency of the one or more second signals is less than or equal to 100 MHz, less than or equal to 10 MHz, less than or equal to 1 MHz, less than or equal to 100 kHz, less than or equal to 10 kHz, less than or equal to 1 kHz, or less than or equal to 100 Hz. Combinations of the above recited ranges are also possible (e.g., the resonance frequency of the one or more second signals is greater than or equal to 10 Hz and less than or equal to 10 MHz, the resonance frequency of the one or more second signals is greater than or equal to 10 kHz and less than or equal to 100 MHz). Other ranges are also possible.

According to certain embodiments, the processor may be configured to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded based at least in part on a change in the resonance frequency of the first signal before and after corrosion, using a change in the resonance frequency of the second signal to distinguish changes in the resonance frequency of the first signal that may be due to factors other than corrosion and/or erosion of the first RLC circuit pathway.

In some embodiments, for example, the processor may be configured to: (i) determine a resonance frequency of the first RLC circuit pathway before potential corrosion and/or erosion of the first RLC circuit pathway (RFi ),' and (ii) a resonance frequency of the second RLC circuit pathway before potential corrosion and/or erosion of the first RLC circuit pathway (RF2,t). In certain embodiments, the processor may then be configured to: (i) determine a resonance frequency of the first RLC circuit pathway after potential corrosion and/or erosion of the first RLC circuit pathway (RFify, and (ii) a resonance frequency of the second RLC circuit pathway after potential corrosion and/or erosion of the first RLC circuit pathway (RF2,f). According to some embodiments, the processor may then be configured to: (i) determine the change in the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway (ARFi) by subtracting RFi.i from RFif, and (ii) determine the change in the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway (ARFi) by subtracting RlA.i from RF f. In certain embodiments, the processor may then be configured to compare ARFi and ARF to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded.

According to certain embodiments, for example, if the change in the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway (ARFi) is the same as the change in the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway (ARF2), then the processor may determine that the change in the resonance frequency of the first RLC circuit pathway is not due to corrosion and/or erosion of the first RLC circuit pathway. In certain embodiments, for example, the change in the resonance frequency of the first RLC circuit pathway may be due to factors other than corrosion and/or erosion, such as the presence of structural defects such as cracks, mechanical strain, etc.

In some embodiments, if the change in the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway (ARFi) is different than the change in the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway (ARF2), then the processor may determine that the change in the resonance frequency of the first RLC circuit pathway is due to corrosion and/or erosion of the first RLC circuit pathway.

According to some embodiments, the percentage change between the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway (%ARF) is calculated as follows: where: (i) MFF2 is the absolute difference between the resonance frequency of the second RLC circuit pathway after potential corrosion and/or erosion of the first RLC circuit pathway ( F2f) and before potential corrosion and/or erosion of the first RLC circuit pathway ( F2,i),' (ii) RFi.t is the resonance frequency of the first RLC circuit pathway before potential corrosion and/or erosion of the first RLC circuit pathway; (iii) RF22 is the resonance frequency of the second RLC circuit pathway before potential corrosion of the first RLC circuit pathway; and (iv) ARFi is the absolute difference between the resonance frequency of the first RLC circuit pathway after potential corrosion and/or erosion of the first RLC circuit pathway (RFif) and before potential corrosion and/or erosion of the first RLC circuit pathway (RFi. ).

The percentage change between the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway may be any of a variety of suitable values, In certain embodiments, for example, the percentage change between the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is greater than or equal to 0%, greater than or equal to 1%, greater than or equal to 5%, greater than or equal to 10%, greater than or equal to 15%, greater than or equal to 20%, greater than or equal to 25%, greater than or equal to 30%, greater than or equal to 35%, greater than or equal to 40%, or greater than or equal to 45%. In some embodiments, the percentage change between the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is less than or equal to 50%, less than or equal to 45%, less than or equal to 40%, less than or equal to 35%, less than or equal to 30%, less than or equal to 25%, less than or equal to 20%, less than or equal to 15%, less than or equal to 10%, less than or equal to 5%, or less than or equal to 1%. Combinations of the above recited range are possible (e.g., the percentage change between the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is greater than or equal to 0% and less than or equal to 50%, the percentage change between the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is greater than or equal to 20% and less than or equal to 30%). Other ranges are also possible.

In some embodiments, the change (e.g., percentage change) between the resonance frequency of the first RLC circuit pathway before and after corrosion and/or erosion of the first RLC circuit pathway and the resonance frequency of the second RLC circuit pathway before and after corrosion and/or erosion of the fist RLC circuit pathway is proportional to a thickness of the coating disposed on the portion (e.g., first portion) of the inductor in the first RLC circuit pathway that has corroded and/or eroded. In certain embodiments, for example, the resonance frequency of the first RLC circuit pathway may change by a first amount when the coating disposed on the portion of the inductor has corroded and/or eroded, changing the thickness of the coating from a first thickness to a second thickness, wherein the second thickness is less than the first thickness. In some embodiments, the resonance frequency of the first RLC circuit pathway may change by a second amount that is greater than the first amount when the coating disposed on the portion of the inductor has corroded and/or eroded, changing the thickness of the coating from the second thickness to a third thickness, wherein the third thickness is less than the second thickness. Advantageously, the change (e.g., percentage change) between the resonance frequency of the first RLC circuit pathway before and after corrosion and/or erosion of the first RLC circuit pathway and the resonance frequency of the second RLC circuit pathway before and after corrosion and/or erosion of the fist RLC circuit pathway being proportional to the thickness of the coating disposed on the portion (e.g., first portion) of the inductor in the first RLC circuit pathway that has corroded and/or eroded may be used to determine the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded.

According to some embodiments, the comparison between the first signal of the single circuit and the second signal of the single circuit (e.g., the reference signal of the reference circuit) comprises a comparison between a quality factor (or Q factor) of the one or more first signals and a quality factor of the one or more second signals. As used herein, the phrase “quality factor” is given its ordinary meaning in the art and refers to a ratio of the initial energy stored in an oscillator to the energy lost in one cycle of oscillation. In certain embodiments, the quality factor is calculated using the following equation: wherein f_r is the resonant frequency and Af is the resonance width or full width at half maximum (FWHM).

According to some embodiments, to account for small quality factor values (i.e., less than 1), a 10% quality factor or a 20% quality factor can be calculated according to the equation above, wherein Af is the resonance width or full width at 90% or 80% of the maximum, respectively.

The quality factor of the first signal of the single circuit may be any of a variety of suitable values. In certain embodiments, for example, the quality factor of the first signal is greater than or equal to 0.1, greater than or equal to 0.5, greater than or equal to 1, greater than or equal to 5, greater than or equal to 10, greater than or equal to 15, or greater than or equal to 20. In some embodiments, the quality factor of the first signal is less than or equal to 50, less than or equal to 20, less than or equal to 15, less than or equal to 10, less than or equal to 5, less than or equal to 1, or less than or equal to 0.5. Combinations of the above recited ranges are possible (e.g., the quality factor of the first signal is greater than or equal to 0.5 and less than or equal to 50, the quality factor of the first signal is greater than or equal to 5 and less than or equal to 10). Other ranges are also possible.

The quality factor of the second signal of the single circuit may be any of a variety of suitable values. In certain embodiments, for example, the quality factor of the second signal is greater than or equal to 0.1, greater than or equal to 0.5, greater than or equal to 1, greater than or equal to 5, greater than or equal to 10, greater than or equal to 15, greater than or equal to 20, or greater than or equal to 25. In some embodiments, the quality factor of the second signal is less than or equal to 50, less than or equal to 25, less than or equal to 20, less than or equal to 15, less than or equal to 10, less than or equal to 5, less than or equal to 1, or less than or equal to 0.5. Combinations of the above recited ranges are possible (e.g., the quality factor of the second signal is greater than or equal to 0.5 and less than or equal to 50, the quality factor of the second signal is greater than or equal to 5 and less than or equal to 10). Other ranges are also possible.

According to some embodiments, the processor may be configured to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded based at least in part on a change in the quality factor of the first signal before and after corrosion, using a change in the quality factor of the second signal to distinguish changes in the quality factor of the first signal that may be due to factors other than corrosion and/or erosion.

In some embodiments, for example, the processor may be configured to: (i) determine a quality factor of the first RLC circuit pathway before potential corrosion and/or erosion of the first RLC circuit pathway ( ,/); and (ii) a quality factor of the second RLC circuit pathway before potential corrosion and/or erosion of the first RLC circuit pathway Q2Q. In certain embodiments, the processor may then be configured to: (i) determine a quality factor of the first RLC circuit pathway after potential corrosion and/or erosion of the first RLC circuit pathway (Qi,f),' and (ii) a quality factor of the second RLC circuit pathway after potential corrosion and/or erosion of the first RLC circuit pathway Q2,f . According to some embodiments, the processor may then be configured to: (i) determine a change in the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway AQi by subtracting Qi,i from Qif, and (ii) determine a change in the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway ( O2) by subtracting Q22 from Q2,f. In certain embodiments, the processor may then be configured to compare AQi and AQ2 to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded.

According to certain embodiments, for example, if the change in the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway (AQi) is the same as the change in the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway (AQ2), then the processor may determine that the change in the quality factor of the first RLC circuit pathway is not due to corrosion and/or erosion of the first RLC circuit pathway. In certain embodiments, for example, the change in the quality factor of the first RLC circuit pathway may be due to factors other than corrosion and/or erosion, such as the presence of structural defects such as cracks, mechanical strain, etc.

In some embodiments, if the change in the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway ( Qi) is different than the change in the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway (AQi), then the processor may determine that the change in the quality factor of the first RLC circuit pathway is due to corrosion and/or erosion of the first RLC circuit pathway. According to some embodiments, the percentage change between the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway where: (i) A L is the absolute difference between the quality factor of the second RLC circuit pathway after potential corrosion and/or erosion of the first RLC circuit pathway (02/) and before potential corrosion and/or erosion of the first RLC circuit pathway (02,/); (ii) Qi, i is the quality factor of the first RLC circuit pathway before potential corrosion and/or erosion of the first RLC circuit pathway; (iii) Q2 is the quality factor of the second RLC circuit pathway before potential corrosion of the first RLC circuit pathway; and (iv) A / is the absolute difference between the quality factor of the first RLC circuit pathway after potential corrosion and/or erosion of the first RLC circuit pathway (Qif) and before potential corrosion and/or erosion of the first RLC circuit pathway (Qi ).

The percentage change between the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway may be any of a variety of suitable values. In certain embodiments, for example, the percentage change between the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is greater than or equal to 0%, greater than or equal to 1%, greater than or equal to 5%, greater than or equal to 10%, greater than or equal to 15%, greater than or equal to 20%, greater than or equal to 25%, greater than or equal to 30%, greater than or equal to 35%, greater than or equal to 40%, or greater than or equal to 45%. In some embodiments, the percentage change between the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is less than or equal to 50%, less than or equal to 45%, less than or equal to 40%, less than or equal to 35%, less than or equal to 30%, less than or equal to 25%, less than or equal to 20%, less than or equal to 15%, less than or equal to 10%, less than or equal to 5%, or less than or equal to 1%. Combinations of the above recited range are possible (e.g., the percentage change between the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is greater than or equal to 1% and less than or equal to 50%, the percentage change between the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway and the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is greater than or equal to 20% and less than or equal to 30%). Other ranges are also possible.

In some embodiments, the change (e.g., percentage change) between the quality factor of the first RLC circuit pathway before and after corrosion and/or erosion of the first RLC circuit pathway and the quality factor of the second RLC circuit pathway before and after corrosion and/or erosion of the first RLC circuit pathway is proportional to a thickness of the coating disposed on the portion (e.g., first portion) of the inductor in the first RLC circuit pathway that has corroded and/or eroded. In certain embodiments, for example, the quality factor of the first RLC circuit pathway may change by a first amount when the coating disposed on the portion of the inductor has corroded and/or eroded, changing the thickness of the coating from a first thickness to a second thickness, wherein the second thickness is less than the first thickness. In some embodiments, the quality factor of the first RLC circuit pathway may change by a second amount that is greater than the first amount when the coating disposed on the portion of the inductor has corroded and/or eroded, changing the thickness of the coating from the second thickness to a third thickness, wherein the third thickness is less than the second thickness. Advantageously, the change (e.g., percentage change) between the quality factor of the first RLC circuit pathway before and after corrosion and/or erosion of the first RLC circuit pathway and the quality factor of the second RLC circuit pathway before and after corrosion and/or erosion of the fist RLC circuit pathway being proportional to the thickness of the coating disposed on the portion (e.g., first portion) of the inductor in the first RLC circuit pathway that has corroded and/or eroded may be used to determine the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded.

Referring to FIG. 5, according to certain embodiments, sensor system 500 is a wireless sensor system. In some embodiments, for example, sensor system 500 comprises wireless communication module 506. Wireless communication module 506 may be configured, in some embodiments, to wirelessly communicate information external to sensor system 500. In some embodiments, for example, wireless communication module 506 may be configured to send a signal (e.g., a wireless signal) to circuit 100.

One or more components of sensor system 500 may be disposed in a housing (not shown in FIG. 6). For example, circuit 100, energy storage module 502, processor 504, and/or wireless communication module 506 may be housed in a housing. Optionally or additionally, processor 504 may be provided outside the housing, for example, as a remote processor in the cloud that is coupled to circuit 100 and/or wireless communication module 506 using any suitable communication means.

As noted above, in some embodiments, the circuits described herein can be used as RLC circuits (e.g., wireless RLC circuits). FIG. 6 is a schematic illustration showing one mode of operation, in which resonant inductive pulse-echo methods are employed.

The idea of the pulse-echo non-invasive sensor architecture, in accordance with certain embodiments, is to keep the embedded sensing circuit as simple as possible and move the complexity to the reader. The measurement approach is, in accordance with certain embodiments, “pulse echo.” In such embodiments, a reader can apply a drive waveform to power the resonator. In some embodiments, the drive waveform is subsequently removed for detection. After removing the drive waveform, the circuit can generate a signal (e.g., a decaying signal in a frequency of the inductor and capacitor), which can be used to determine a mechanical characteristic of the circuit. In some embodiments, determining the mechanical characteristic of the circuit comprises determining whether a mechanical transformation has occurred in the circuit; determining the type of mechanical transformation that has occurred in the circuit; and/or determining whether a portion of the circuit has corroded and/or eroded. For example, in accordance with some embodiments, if a mechanical transformation has occurred in the circuit, the signal that is returned to the reader by the circuit exhibits a change in the resonance frequency of the circuit and/or a change in the quality factor of the circuit; but if a mechanical transformation has not occurred in the circuit, the signal that is returned to the reader by the sensor does not exhibit a change in the resonance frequency of the circuit and/or a change in the quality factor of the circuit. As one example, the reader can use, in some embodiments, ADC to sample the information and can perform a finite Fourier transform (FFT) to estimate the change in the resonance frequency of the circuit and/or the change in the quality factor of the circuit, and can map the change in the resonance frequency of the circuit and/or the change in the quality factor of the circuit to a mechanical transformation.

According to certain embodiments, a method for operating a sensor system is described. In some embodiments, the method comprises applying energy to a portion of a sensor system (e.g., a circuit of a sensor system). For example, in certain embodiments, the sensor system is a wireless sensor system and the applying comprises applying electromagnetic radiation (e.g., a drive waveform) from a reader to the circuit of the wireless sensor system. In other embodiments, the sensor system is a wired sensor system and the applying comprises applying power (e.g., voltage and/or current) from a power supply (e.g., an energy storage module) to the circuit of the wired sensor system. As a result of applying energy to the circuit, the circuit may produce a signal, in some embodiments. According to certain embodiments, the signal of the circuit may be produced from a RLC circuit pathway (e.g., a first RLC circuit pathway and/or a second RLC circuit pathway). The signal may be a return signal that is returned to the reader, in some embodiments. In certain embodiments, the method comprises measuring, with the sensor system one or more first signals of a single circuit disposed in the sensor system. In some embodiments, for example, the one or more first signals of the single circuit correspond to one or more signals (e.g., one or more return signals) from the first RLC circuit pathway, wherein a portion of the first RLC circuit pathway has corroded and/or eroded. In some embodiments, the measuring comprises measuring the one or more first signals with a reader. According to some embodiments, the measuring comprises measuring the one or more first signals with a “pulse echo” approach, as shown in FIG. 6 and described herein in greater detail. In certain embodiments, the one or more first signals may be one or more oscillating signals of the single circuit.

In some embodiments, the method comprises measuring, with the sensor system, one or more second signals of the single circuit disposed in the sensor system. In some embodiments, for example, the one or more second signals of the single circuit correspond to one or more signals (e.g., one or more return signals) from the second RLC circuit pathway (e.g., the reference circuit), wherein a portion of the second RLC circuit pathway has not corroded and/or eroded. In certain embodiments, the measuring comprises measuring the one or more second signals with a reader. According to some embodiments, the measuring comprises measuring the one or more second signals with “pulse echo” approach, as shown in FIG. 6 and described herein in greater detail. In certain embodiments, the one or more second signals may be one or more oscillating signals of the single circuit.

In some embodiments, the method comprises transmitting signals to and/or receiving signals (e.g., the one or more first signals and the one or more second signals) with a processor. In some embodiments, the processor can be used to compare a property of the one or more first signals (e.g., a resonance frequency and/or quality factor of the one or more first signals, for example, wherein a portion of the first RLC circuit pathway has corroded and/or eroded) to a corresponding property of the one or more second signals (e.g., a resonance frequency and/or quality factor of the one or more second signals, for example, wherein a portion of the second RLC circuit pathway has not corroded and/or eroded).

According to certain embodiments, the method comprises determining, with the processor, whether a portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded based at least in part on a comparison between the one or more first signals of the single circuit and the one or more second signals (e.g., the one or more reference signals) of the single circuit.

In some embodiments, the method comprises determining, with a processor, a comparison between a resonance frequency of the one or more first signals (e.g., wherein a portion of the first RLC circuit pathway has corroded and/or eroded) and a resonance frequency of the one or more second signals (e.g., wherein a portion of the second RLC circuit pathway has not corroded and/or eroded). In certain embodiments, for example, the method comprises determining, with a processor, whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded based at least in part on a change in the resonance frequency of the first signal before and after potential corrosion, using a change in the resonance frequency of the second signal to distinguish changes in the resonance frequency of the first signal that may be due to factors other than corrosion and/or erosion of the first RLC circuit pathway. For example, in some embodiments, the method comprises determining, with a processor, whether the change in the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is the same as the change in the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway, an indication that the change in the resonance frequency of the first RLC circuit pathway is not due to corrosion and/or erosion of the first RLC circuit pathway. In some embodiments, the method comprises determining, with a processor, whether the change in the resonance frequency of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is different than the change in the resonance frequency of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway, an indication that the change in the resonance frequency of the first RLC circuit pathway is due to corrosion and/or erosion of the first RLC circuit pathway.

In certain embodiments, the method comprises determining, with a processor, a comparison between a quality factor of the one or more first signals (e.g., wherein a portion of the first RLC circuit pathway has corroded and/or eroded) and a quality factor of the one or more second signals (e.g., wherein a portion of the second RLC circuit pathway has not corroded and/or eroded). In certain embodiments, for example, the method comprises determining, with a processor, whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded based at least in part on a change in the quality factor of the first signal before and after potential corrosion, using a change in the quality factor of the second signal to distinguish changes in the quality factor of the first signal that may be due to factors other than corrosion and/or erosion of the first RLC circuit pathway. For example, in some embodiments, the method comprises determining, with a processor, whether the change in the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is the same as the change in the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway, an indication that the change in the quality factor of the first RLC circuit pathway is not due to corrosion and/or erosion of the first RLC circuit pathway. In some embodiments, the method comprises determining, with a processor, whether the change in the quality factor of the first RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway is different than the change in the quality factor of the second RLC circuit pathway before and after potential corrosion and/or erosion of the first RLC circuit pathway, an indication that the change in the quality factor of the first RLC circuit pathway is due to corrosion and/or erosion of the first RLC circuit pathway.

An example of a comparison of a resonance frequency of a first signal of a single circuit and a resonance frequency of a second signal of a single circuit is shown in FIG. 7. As shown in FIG. 7, the resonance frequency of the first signal is between 500-600 kHZ, and the resonance frequency of the second signal is between 1-1.5 MHz. According to some embodiments, the resonance frequency of the first signal may correspond to a resonance frequency of a first RLC circuit pathway of the single circuit, and the resonance frequency of the second signal (e.g., a reference signal) may correspond to a resonance frequency of a second RLC circuit pathway (e.g., a reference circuit) of the single circuit. In some embodiments, a processor associated with a sensor system comprising the single circuit may be configured to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded based at least in part on a change in the resonance frequency of the first signal before and after corrosion, using a change in the resonance frequency of the second signal to distinguish changes in the resonance frequency of the first signal that may be due to factors other than corrosion and/or erosion of the first RLC circuit pathway.

While several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, and/or methods, if such features, systems, articles, materials, and/or methods are not mutually inconsistent, is included within the scope of the present invention.

The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to “A and/or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

Some embodiments may be embodied as a method, of which various examples have been described. The acts performed as part of the methods may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include different (e.g., more or less) acts than those that are described, and/or that may involve performing some acts simultaneously, even though the acts are shown as being performed sequentially in the embodiments specifically described above.

Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

Claims

CLAIMS What is claimed is:

1. A sensor system, comprising: a single circuit comprising: a first RLC circuit pathway; and a second RLC circuit pathway, wherein at least a portion of the first RLC circuit pathway is configured to corrode and/or erode and the second RLC circuit pathway is configured as a reference circuit such that the circuit signal(s) can be used to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded.

2. The sensor system of claim 1, wherein the sensor system is a wireless sensor system.

3. The sensor system of any one of claims 1-2, wherein the first RLC circuit pathway comprises a first portion of an inductor comprising elongated nanostructures that serve an electronic function of the inductor.

4. The sensor system of claim 3, wherein the first portion of the inductor comprises a coating disposed on the elongated nanostructures.

5. The sensor system of claim 4, wherein the coating comprises a metal.

6. The sensor system of any one of claims 4-5, wherein the coating is configured to corrode and/or erode.

7. The sensor system of any one of claims 3-6, wherein the first RLC circuit pathway comprises a first capacitor comprising elongated nanostructures that serve an electronic function of the capacitor.

8. The sensor system of claim 7, wherein a first electrode of the first capacitor is electronically coupled to the first portion of the inductor via a first electronically conductive pathway, and wherein a second electrode of the first capacitor is electronically coupled to the first portion of the inductor via a second electronically conductive pathway.

9. The sensor system of any one of claims 3-8, wherein the second RLC circuit pathway comprises a second portion of the inductor.

10. The sensor system of any one of claims 8-9, wherein the second RLC circuit pathway comprises a second capacitor comprising elongated nanostructures that serve an electronic function of the capacitor.

11. The sensor system of claim 10, wherein a first electrode of the second capacitor is electronically coupled to the second portion of the inductor via the second electronically conductive pathway, and wherein a second electrode of the second capacitor is electronically coupled to the second portion of the inductor via a third electronically conductive pathway.

12. A method for operating a sensor system, comprising: measuring, with the sensor system, a first signal of a single circuit disposed in the sensor system, wherein the single circuit comprises: a first RLC circuit pathway; and a second RLC circuit pathway, wherein at least a portion of the first RLC circuit pathway is configured to corrode and/or erode and the second RLC circuit pathway is configured as a reference circuit such that the circuit signal(s) can be used, at least in part, to determine whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded; measuring, with the sensor system, a second signal of the single circuit, wherein the second signal is a reference signal of the reference circuit; and determining, with a processor, whether the portion of the first RLC circuit pathway has corroded and/or eroded and/or the degree to which the portion of the first RLC circuit pathway has corroded and/or eroded based at least in part on a comparison between the first signal and the second signal.

13. The method of claim 12, wherein the sensor system is a wireless sensor system.

14. The method of any one of claims 12-13, further comprising providing, with an energy storage module configured to store electrical energy, power to at least a portion of the single circuit.

15. The method of any one of claims 12-14, wherein the first signal of the single circuit is an oscillating signal of the single circuit.

16. The method of any one of claims 12-15, wherein the second signal of the single circuit is an oscillating signal of the single circuit.

17. The method of any one of claims 12-16, further comprising transmitting signals representing the first signal of the single circuit and the second signal of the single circuit from the single circuit to the processor.

18. The method of any one of claims 12-17, wherein the comparison comprises a comparison of a resonance frequency of the first signal and a resonance frequency of the second signal.

19. The method of any one of claims 12-18, wherein the comparison comprises a comparison of: (i) a resonance frequency of the first signal before and after potential corrosion and/or erosion of the first RLC circuit pathway; and (ii) a resonance frequency of the second signal before and after potential corrosion and/or erosion of the first RLC circuit pathway.

20. The method of any one of claims 12-19, wherein the comparison comprises a comparison of a quality factor of the first signal and a quality factor of the second signal.

21. The method of any one of claims 12-20, wherein the comparison comprises a comparison of: (i) a quality factor of the first signal before and after potential corrosion and/or erosion of the first RLC circuit pathway; and (ii) a quality factor of the second signal before and after potential corrosion and/or erosion of the first RLC circuit pathway.