CN115575464A - Self-calibrating humidity sensor - Google Patents

Abstract

A self-calibrating humidity sensor comprising: the capacitive touch sensor comprises a substrate, a first insulating layer coated on the substrate, a heating device arranged on the first insulating layer, a second insulating layer coated on the heating device and separated from the first insulating layer, a reference capacitor arranged on the second insulating layer and a humidity sensing capacitor arranged on the second insulating layer and arranged above the heating device. The humidity sensing capacitor comprises an interdigital capacitor arranged on the second insulating layer and a humidity sensitive material layer covering the interdigital capacitor. Through setting up benchmark electric capacity and feeling wet electric capacity, through the heating to the moisture sensitive material layer that feels on the wet electric capacity, and make the evaporation of adsorbed steam in this moisture sensitive material layer to make the capacitance value of feeling wet electric capacity reply initial nothing wet state's numerical value, and through comparing with benchmark electric capacity, and realized the calibration to feeling wet electric capacity parameter value, finally realized humidity transducer's automatic calibration, provided humidity measurement's accuracy, avoided or weakened measuring error.

Description

Self-calibrating humidity sensor

Technical Field

The invention relates to the technical field of sensors, in particular to a humidity sensor, and more particularly relates to a self-calibration humidity sensor.

Background

The humidity sensor is a humidity sensing device which is frequently used in production and life, is widely applied to the fields of indoor humidity measurement, smart home, white household appliances, agriculture and the like, and plays a great role. Common humidity sensors are mostly humidity sensors implemented by capacitance principle, because the capacitive humidity sensors have many advantages, such as easy processing by CMOS process, strong compatibility, good linearity, wide humidity range (e.g. from 0-100% rh).

The capacitance type humidity sensor adopts a high molecular polymer material as a humidity sensitive material, and the humidity sensitive material is arranged on the humidity sensitive capacitor, when the humidity of the surrounding environment changes, the content of water vapor attached to the humidity sensitive material changes, so that the capacitance of the humidity sensitive capacitor changes, and the measurement of the humidity of the surrounding environment is realized through the change of the capacitance.

However, humidity sensors using high molecular polymer materials have a temperature drift problem. Due to the inherent characteristics of the high molecular polymer, chemical adsorption moisture is inevitably formed on the material, and the chemical adsorption moisture is difficult to desorb from the surface of the polymer, so that drift is generated, and particularly under a high-humidity environment, the long-chain space position of the high molecular polymer expands, and the humidity drift characteristic is more obvious. In other words, after the sensor is used for a long time, the high polymer material itself may age to cause data output to drift, that is, zero position shifts. The humidity sensor specification book may have a parameter related to drift rate such as 2%/year. The temperature drift phenomenon described above may cause a large error in the humidity measurement value of the humidity sensor.

Disclosure of Invention

The present invention provides a self-calibrating humidity sensor, so as to solve the above problems in the prior art, and avoid or reduce the technical defect of humidity measurement accuracy deterioration caused by temperature drift.

In order to meet the purpose of the invention, the invention adopts the following technical scheme:

a self-calibrating humidity sensor comprising:

the capacitive touch sensor comprises a substrate, a first insulating layer coated on the substrate, a heating device arranged on the first insulating layer, a second insulating layer coated on the heating device and separated from the first insulating layer, a reference capacitor arranged on the second insulating layer and a humidity sensing capacitor arranged on the second insulating layer and arranged at a position above the heating device; the humidity sensing capacitor comprises an interdigital capacitor arranged on the second insulating layer and a humidity sensitive material layer covering the interdigital capacitor.

Preferably, further comprising: the data acquisition unit is in communication connection with the reference capacitor and the humidity sensing capacitor and is used for acquiring corresponding capacitance values of the reference capacitor and the humidity sensing capacitor; and the analysis processing unit is respectively in communication connection with the data acquisition unit and the heating device and is used for comparing the two capacitance values acquired by the data acquisition unit, controlling the heating device to heat the humidity sensing capacitor for a preset time period when the comparison results are different, and continuously executing the step of acquiring the corresponding capacitance values of the reference capacitor and the humidity sensing capacitor and the step of comparing the two capacitance values acquired by the data acquisition unit after the heating process of the preset time period is finished.

Preferably, the substrate is a silicon-based substrate. Further preferably, the first insulating layer and the second insulating layer are both silicon oxide insulating films, and have a thickness of 100 to 400nm. The silicon dioxide insulating film with the thickness can improve better insulating property, especially electrical insulating property at high temperature and high heat.

Preferably, the reference capacitance includes: linear anodal arm, set up with even interval linear anodal on the arm a set of positive interdigital, with linear anodal arm relative its parallel arrangement's linear negative pole arm, set up with even interval linear negative pole on the arm interdigital, locate the positive terminal of a linear tip of linear anodal arm, and locate the negative terminal of a linear tip of linear negative pole arm.

Further preferably, the interdigital capacitor comprises: linear positive pole arm, set up with even interval linear positive pole arm on a set of positive pole interdigital, with linear positive pole arm is relative its parallel arrangement's linear negative pole arm, is set up with even interval linear negative pole arm on the linear negative pole arm a set of negative pole interdigital, locate the positive terminal of a linear tip of linear positive pole arm, and locate the negative terminal of a linear tip of linear negative pole arm.

Preferably, the heating device comprises a positive electrode, a negative electrode and a circuitous heating loop electrically connected between the positive electrode and the negative electrode. Further preferably, one of the positive electrode and the negative electrode is a tantalum electrode, the other electrode is a platinum electrode, the thickness of the tantalum electrode is 0.01-0.5 micrometers, and the thickness of the platinum electrode is 0.1-0.5 micrometers. Electrodes of this material and thickness can provide greater conductivity and stability. Preferably, the moisture sensitive material layer is a polyimide material layer having a thickness of 1 to 5 micrometers.

Preferably, the self-calibration humidity sensor further comprises an output module, communicatively connected to the analysis processing unit, for outputting the comparison result to a user when the comparison results of the two capacitance values are the same.

The invention also provides a self-calibration method of the self-calibration humidity sensor, which comprises the following steps:

step S101: acquiring two capacitance values corresponding to a reference capacitor and a humidity sensing capacitor;

step S102: judging whether the two capacitance values are the same, if so, sequentially executing steps S103, S101 and S102, and if so, executing step S104;

step S103: heating the humidity sensing capacitor for a preset time period; and

step S104: and outputting two comparison results with the same capacitance value.

Compared with the prior art, the invention has the following advantages:

in the self-calibration humidity sensor structure, the self-calibration module and the self-calibration method provided by the invention, two capacitors are arranged on the self-calibration humidity sensor, one capacitor is a reference capacitor, the other capacitor is a humidity sensing capacitor, and water vapor adsorbed in a humidity sensitive material layer on the humidity sensitive capacitor is evaporated by heating the humidity sensitive material layer, so that the capacitance value of the humidity sensitive capacitor is recovered to the initial value without humidity, and the calibration of the humidity sensitive capacitor parameter value is realized by comparing the humidity sensitive capacitor with the reference capacitor on which the humidity sensitive material layer is not arranged, thereby finally realizing the automatic calibration of the humidity sensor, providing the accuracy of humidity measurement and avoiding or weakening the measurement error caused by the temperature drift characteristic of the humidity sensitive material.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a cross-sectional layered block diagram of a self-calibrating humidity sensor of the present invention illustrating the physical structure of a number of different structural components of the sensor of the present invention, such as the reference capacitor, the humidity sensing capacitor, and the heating device.

FIG. 2 is a detailed block diagram of the reference capacitance and the humidity sensing capacitance of the self-calibrating humidity sensor shown in FIG. 1.

FIG. 3 is a detailed block diagram of the heating apparatus of the self-calibrating humidity sensor shown in FIG. 1.

FIG. 4 illustrates a block flow diagram of the operation of the self-calibrating humidity sensor of the present invention.

FIG. 5 illustrates a flow chart of a method of self-calibrating a self-calibrating humidity sensor of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are exemplary only for the purpose of illustrating the invention and are not to be construed as limiting the invention.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or wirelessly coupled. As used herein, the term "and/or" includes all or any element and all combinations of one or more of the associated listed items.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The invention provides a self-calibration humidity sensor, which is characterized in that two capacitors are arranged on the sensor, one of the capacitors is a reference capacitor, the other two capacitors are humidity sensing capacitors, a humidity sensitive material layer on each humidity sensing capacitor is heated to evaporate water vapor adsorbed in the humidity sensitive material layer, so that the capacitance value of each humidity sensing capacitor returns to the initial value of a no-humidity state, and the humidity sensing capacitor is compared with the reference capacitor on which the humidity sensitive material layer is not arranged, so that the calibration of the parameter value of each humidity sensing capacitor is realized, the automatic calibration of the humidity sensor is finally realized, the accuracy of humidity measurement is provided, and the measurement error caused by the temperature drift characteristic of the humidity sensitive material is avoided or weakened.

In an exemplary embodiment of the present invention, and with reference to fig. 1-5, a self-calibrating humidity sensor 100 includes: a substrate 10, a first insulating layer 20 coated on the substrate 10, a heating device 30 disposed on the first insulating layer 20, a second insulating layer 40 coated on the heating device 30 and spaced apart from the first insulating layer 20, a reference capacitor 70 (refer to fig. 2) and a humidity-sensing capacitor 50 disposed on the second insulating layer 40; the humidity sensing capacitor 50 comprises an interdigital capacitor 52 arranged on the second insulating layer 40 and a humidity sensitive material layer 54 covering the interdigital capacitor 52; the heating device 30 is disposed under the interdigital capacitor 52 to heat and dehumidify the humidity sensitive material layer 54.

FIG. 4 illustrates a functional block diagram of the self-calibration of the self-calibrating humidity sensor of the present invention. As shown in fig. 4, the self-calibrating humidity sensor further comprises:

a data obtaining unit 80, communicatively connected to the reference capacitor 70 and the humidity-sensing capacitor 50, for obtaining corresponding capacitance values of the reference capacitor 70 and the humidity-sensing capacitor 50;

an analysis processing unit 90, which is respectively connected to the data acquisition unit 80 and the heating device 30 in a communication manner, and is used for comparing the two capacitance values acquired by the data acquisition unit 80, controlling the heating device 30 to heat the humidity sensing capacitor 50 for a predetermined period of time when the comparison results are different, and continuing to execute the process of judging the comparison result after the heating process of the predetermined period of time is finished; and

and an output module 200, communicatively connected to the analysis processing unit 90, for outputting the comparison result to a user when the comparison results of the two capacitance values are the same.

The invention also provides a self-calibration method for the self-calibration humidity sensor, as shown in fig. 5, which comprises the following steps:

step S101: acquiring two capacitance values corresponding to a reference capacitor and a humidity sensing capacitor;

step S102: judging whether the two capacitance values are the same, if so, sequentially executing steps S103, S101 and S102, and if so, executing step S104;

step S103: heating the humidity sensing capacitor for a preset time period; and

step S104: and outputting two comparison results with the same capacitance value.

It should be noted that: in the execution process of each step, the execution subject or the recipient corresponds to each functional module. In other words, the steps are executed or implemented by the above functional units or modules, and are not described herein again.

In the self-calibration humidity sensor structure, the self-calibration module and the self-calibration method provided by the invention, two capacitors are arranged on the self-calibration humidity sensor, one capacitor is a reference capacitor, the other capacitor is a humidity sensing capacitor, and water vapor adsorbed in a humidity sensitive material layer on the humidity sensitive capacitor is evaporated by heating the humidity sensitive material layer, so that the capacitance value of the humidity sensitive capacitor is recovered to the initial value without humidity, and the calibration of the humidity sensitive capacitor parameter value is realized by comparing the humidity sensitive capacitor with the reference capacitor on which the humidity sensitive material layer is not arranged, thereby finally realizing the automatic calibration of the humidity sensor, providing the accuracy of humidity measurement and avoiding or weakening the measurement error caused by the temperature drift characteristic of the humidity sensitive material.

Preferably, the substrate 10 is a silicon-based substrate. More preferably, the first insulating layer 20 and the second insulating layer 40 are both silicon dioxide insulating films, and the thickness thereof is 100 to 400nm. The silicon dioxide insulating film with the thickness can improve better insulating property, especially the electric insulating property at high temperature and high heat. The two insulating layers are disposed to electrically isolate the heating device 30, the substrate 10 and the humidity sensing capacitor 50 from each other, so as to prevent, for example, external moisture from falling onto the heating device 30, which may cause a short circuit of an internal circuit of the heating device 30 to burn the heating device 30, which may result in the heating device 30 failing to heat and dehumidify the humidity sensitive material layer 54 on the humidity sensing capacitor 50, which may ultimately affect the humidity measurement accuracy of the entire self-calibration humidity sensor 100 and cause a large temperature drift phenomenon.

Further preferably, with reference to fig. 2, the reference capacitor 70 comprises: a linear positive electrode arm 71, a set of positive electrode fingers 712 disposed at uniform intervals on the linear positive electrode arm 71, a linear negative electrode arm 72 disposed in parallel with the linear positive electrode arm 71 opposite thereto, a set of negative electrode fingers 722 disposed at uniform intervals on the linear negative electrode arm 72, a positive electrode terminal 72 disposed at one linear end of the linear positive electrode arm 71, and a negative electrode terminal 74 disposed at one linear end of the linear negative electrode arm 72.

The interdigital capacitor 52 includes: the linear positive electrode comprises a linear positive electrode arm 51, a group of positive electrode fingers 512 arranged on the linear positive electrode arm 51 at uniform intervals, a linear negative electrode arm 53 arranged in parallel with the linear positive electrode arm 51, a group of negative electrode fingers 532 arranged on the linear negative electrode arm 53 at uniform intervals, a positive electrode terminal 58 arranged at one linear end part of the linear positive electrode arm 51, and a negative electrode terminal 56 arranged at one linear end part of the linear negative electrode arm 53.

With further reference to fig. 3, the heating device 30 includes an anode 32, a cathode 34, and a circuitous heating loop 36 electrically connected therebetween. When a suitable voltage is applied between the positive and negative electrodes 32, 34, the generated current flows in the circuitous heating loop 36 to generate the required heat, thereby heating the moisture sensitive material layer 54, so that the moisture attached on or in the moisture sensitive material layer 54 is evaporated with the gradually increasing temperature, thereby ensuring that the sensing capacitor 50 is in a moisture-free state.

Preferably, one of the positive electrode 32 and the negative electrode 34 is a tantalum electrode and the other electrode is a platinum electrode, and the tantalum electrode preferably has a thickness of 0.01 to 0.5 micrometers and the platinum electrode preferably has a thickness of 0.1 to 0.5 micrometers. Electrodes of this material and thickness can provide greater conductivity and stability.

Further preferably, the layer of moisture sensitive material 54 is a layer of polyimide material and the thickness of the layer of material is 1-5 microns.

Those of skill in the art will appreciate that the various operations, methods, steps in the processes, acts, or solutions discussed in this application can be interchanged, modified, combined, or eliminated. Further, other steps, measures, or schemes in various operations, methods, or flows that have been discussed in this application can be alternated, altered, rearranged, broken down, combined, or deleted. Further, steps, measures, schemes in the prior art having various operations, methods, procedures disclosed in the present application may also be alternated, modified, rearranged, decomposed, combined, or deleted.

The foregoing is only a partial embodiment of the present application, and it should be noted that, for those skilled in the art, several modifications and decorations can be made without departing from the principle of the present application, and these modifications and decorations should also be regarded as the protection scope of the present application.

Claims (10)

1. A self-calibrating humidity sensor, comprising: the capacitive touch sensor comprises a substrate, a first insulating layer coated on the substrate, a heating device arranged on the first insulating layer, a second insulating layer coated on the heating device and separated from the first insulating layer, a reference capacitor arranged on the second insulating layer and a humidity sensing capacitor arranged on the second insulating layer and arranged at a position above the heating device; the humidity sensing capacitor comprises an interdigital capacitor arranged on the second insulating layer and a humidity sensitive material layer covering the interdigital capacitor.

2. The self-calibrating humidity sensor of claim 1, further comprising: the data acquisition unit is in communication connection with the reference capacitor and the humidity sensing capacitor and is used for acquiring corresponding capacitance values of the reference capacitor and the humidity sensing capacitor; and the analysis processing unit is respectively in communication connection with the data acquisition unit and the heating device and is used for comparing the two capacitance values acquired by the data acquisition unit, controlling the heating device to heat the humidity sensing capacitor for a preset time period when the comparison results are different, and continuously executing the step of acquiring the corresponding capacitance values of the reference capacitor and the humidity sensing capacitor and the step of comparing the two capacitance values acquired by the data acquisition unit after the heating process of the preset time period is finished.

3. The self-calibrating humidity sensor of claim 1, wherein: the substrate is a silicon-based substrate; the first insulating layer and the second insulating layer are both silicon dioxide insulating films, and the thicknesses of the first insulating layer and the second insulating layer are both 100-400nm.

4. The self-calibrating humidity sensor of claim 1, wherein: the reference capacitance includes: linear positive pole arm, set up with even interval linear positive pole arm on a set of positive pole interdigital, with linear positive pole arm is relative its parallel arrangement's linear negative pole arm, is set up with even interval linear negative pole arm on the linear negative pole arm a set of negative pole interdigital, locate the positive terminal of a linear tip of linear positive pole arm, and locate the negative terminal of a linear tip of linear negative pole arm.

5. The self-calibrating humidity sensor of claim 4, wherein: the interdigital capacitor comprises: linear positive pole arm, set up with even interval linear positive pole arm on a set of positive pole interdigital, with linear positive pole arm is relative its parallel arrangement's linear negative pole arm, is set up with even interval linear negative pole arm on the linear negative pole arm a set of negative pole interdigital, locate the positive terminal of a linear tip of linear positive pole arm, and locate the negative terminal of a linear tip of linear negative pole arm.

6. The self-calibrating humidity sensor of claim 5, wherein: the heating device comprises an anode, a cathode and a circuitous heating loop electrically connected between the anode and the cathode.

7. The self-calibrating humidity sensor of claim 6, wherein: one of the positive electrode and the negative electrode is a tantalum electrode, the other electrode is a platinum electrode, the thickness of the tantalum electrode is 0.01-0.5 micrometer, and the thickness of the platinum electrode is 0.1-0.5 micrometer.

8. The self-calibrating humidity sensor of claim 1, wherein: the humidity sensitive material layer is a polyimide material layer with the thickness of 1-5 microns.

9. The self-calibrating humidity sensor of claim 1, wherein: the output module is in communication connection with the analysis processing unit and is used for outputting the comparison result to a user when the comparison results of the two capacitance values are the same.

10. A self-calibration method for self-calibrating a humidity sensor, comprising the steps of:

step S101: acquiring two capacitance values corresponding to a reference capacitor and a humidity sensing capacitor;

step S102: judging whether the two capacitance values are the same, if so, sequentially executing steps S103, S101 and S102, and if so, executing step S104;

step S103: heating the humidity sensing capacitor for a preset time period; and

step S104: and outputting two comparison results with the same capacitance value.

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