WO2019089250A1 - Broad range micro pressure sensor - Google Patents
Broad range micro pressure sensor Download PDFInfo
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- WO2019089250A1 WO2019089250A1 PCT/US2018/056828 US2018056828W WO2019089250A1 WO 2019089250 A1 WO2019089250 A1 WO 2019089250A1 US 2018056828 W US2018056828 W US 2018056828W WO 2019089250 A1 WO2019089250 A1 WO 2019089250A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
- B81B3/0018—Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
- B81B3/0021—Transducers for transforming electrical into mechanical energy or vice versa
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/14—Housings
- G01L19/142—Multiple part housings
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
- B81B3/0064—Constitution or structural means for improving or controlling the physical properties of a device
- B81B3/0067—Mechanical properties
- B81B3/0072—For controlling internal stress or strain in moving or flexible elements, e.g. stress compensating layers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
- B81B3/0064—Constitution or structural means for improving or controlling the physical properties of a device
- B81B3/0086—Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/0006—Interconnects
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00023—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems without movable or flexible elements
- B81C1/00111—Tips, pillars, i.e. raised structures
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
- B81C1/00158—Diaphragms, membranes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
- B81C1/00166—Electrodes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
- B81C1/00182—Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L15/00—Devices or apparatus for measuring two or more fluid pressure values simultaneously
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L7/00—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements
- G01L7/02—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges
- G01L7/08—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges of the flexible-diaphragm type
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
- G01L9/0072—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2605—Measuring capacitance
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2201/00—Specific applications of microelectromechanical systems
- B81B2201/02—Sensors
- B81B2201/0264—Pressure sensors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C2201/00—Manufacture or treatment of microstructural devices or systems
- B81C2201/01—Manufacture or treatment of microstructural devices or systems in or on a substrate
- B81C2201/0101—Shaping material; Structuring the bulk substrate or layers on the substrate; Film patterning
- B81C2201/0147—Film patterning
Definitions
- This specification relates to pressure sensor devices and systems.
- a pressure sensor detects or measures a fluid pressure, i.e., a force exerted by a fluid, being the force necessary to oppose the fluid from expanding.
- Pressure sensors are used in a variety of control and monitoring applications and can be used to indirectly measure other physical quantities such as fluid flow, fluid speed, and altitude.
- pressure sensors are fabricated using various techniques and technologies, each of which find use according to performance, application suitability and cost considerations.
- Typical pressure sensors include transducers that generate an electrical signal as a function of the pressure imposed on the transducer, which is an example of a force collector type pressure sensor.
- a force collector type uses a force collector (such as diaphragm, piston, etc.) to measure strain (or deflection) resulting from a force applied to the force collector.
- Types of force collectors include piezo-resistive strain gauge types that use the piezo-resistive effect to detect strain due to applied pressure and a piezoelectric type that uses the piezoelectric effect in certain materials such as quartz, certain ceramics and certain polymers.
- Another type is a capacitive type that uses a diaphragm and pressure cavity to create a variable capacitor to detect strain due to applied pressure.
- Common technologies use metal, ceramic, and silicon diaphragms.
- Such sensors can be fabricated using silicon MEMS (microelectromechanical systems) techniques.
- a pressure sensor includes a plurality of module stages, at least one of the plurality of module stages operative over a first range of pressure and at least one other of the plurality of module stages operative over a second, different range of pressure, with each module stage including a stack of at least two module layers, each module layer including a module body having walls that define a compartment and with the defined compartment partitioned into at least two sub-compartments, a port for fluid ingress or egress disposed in a first wall of the module body, with remaining walls of the module body being solid, a membrane affixed to a first surface of the module body covering the compartment, and an electrode affixed over a surface of the membrane.
- a micro pressure sensor includes a first module operative over a first range of pressure, the first module including a first stack of a first plurality of first module layers, each first module layer including a first module body having walls that define a compartment and with the defined compartment partitioned into at a first plurality of sub-compartments, a first port for fluid ingress or egress disposed in a first wall of the first module body, with remaining walls of the first module body being solid, a first membrane affixed to a first surface of the first module body covering the compartment, and a first electrode affixed over a surface of the first membrane.
- the micro pressure sensor further includes a second module operative over a second, different range of pressure, the second module affixed in the micro pressure sensor, the second module including a second stack of a second plurality of second module layers, each second module layer including a second module body having walls that define a compartment and with the defined compartment partitioned into at a second plurality of sub-compartments that are different in one or more of number and size of sub-compartments than the first plurality of sub-compartment, a second port for fluid ingress or egress disposed in a first wall of the second module body, with remaining walls of the second module body being solid walls, a second membrane affixed to a first surface of the second module body covering the compartment, and an electrode affixed over a surface of the membrane.
- the micro pressure sensors can be used for performing pressure sensing for a variety of industrial, medical, and biological applications.
- the micro pressure sensors can be fabricated using reasonably inexpensive techniques and thus provide inexpensive micro pressure sensors for various applications.
- the micro pressure sensors are fabricated using roll to roll
- micro pressure sensors are operable over a relatively wide range of pressures and have relatively high levels of sensitivity to pressure changes over wide ranges of pressure, relative to a micro pressure sensor comprised of standard sized compartment(s).
- FIGS. 1, 2, 3A and 3 are schematic functional, cross-sectional diagrams of a module stage of a broad range micro pressure sensor showing the micro pressure sensor in a rest mode, an overpressure mode, a greater overpressure mode, and in an under-pressure mode respectively.
- FIG. 4 is an isometric view of a micro pressure sensor comprised of plural repeatable module layers based on the concepts described in FIGS. 1-3.
- FIG. 4A is an isometric view of a module for the micro pressure sensor of
- FIG. 5 is a simplified schematic view showing an equivalence circuit model of capacitance for the modular micro pressure sensor of FIG. 4.
- FIGS. 6A-6C are isometric views of different exemplary body layer patterns for forming sub compartments within modular micro pressure sensors.
- FIG. 7 is an isometric view of the modular micro pressure sensor of FIG. 4 showing a few layers removed.
- FIG. 8 is an isometric view of the modular micro pressure sensor of FIG. 4 showing all layers removed except for spacer members and end caps.
- FIG. 9 is table showing capacitance vs. membrane separation and pressure.
- FIG. 10 is a plot of pressure vs. capacitance.
- FIG. 11 are plots of capacitance v. pressure and membrane separation vs. pressure.
- FIG. 12 is a conceptual diagram of a roll to roll processing configuration.
- FIG. 12A is a conceptual view of some of the exemplary roll to roll processing stations.
- FIGS. 13A-13C are views of roll to roll processing for the structure of FIG. 4, showing the pattern of FIG. 6A.
- FIGS. 14A-14B are views depicting details of via conductors. DETAILED DESCRIPTION
- Micro-pressure sensors described herein are made using micro fabrication methods and can be used for sensing pressure in various industrial, commercial, medical, and biological applications.
- the micro pressure sensors are fabricated on a micron/millimeter scale. Several fabrication techniques are disclosed.
- micro pressure sensors are a narrow pressure range micro pressure sensor as described in my published patent application US-2018-0038754-A1 assigned to the assignee of the present application, and which application is incorporated herein by reference in its entirety.
- narrow range micro pressure sensor is meant that a given module will be operative over a narrow range of pressures relative to a broad range micro pressure sensor.
- the micro pressure sensor of the incorporated by reference application has a single chamber that is
- the narrow range type is a micro pressure sensor having high sensitivities over a relatively narrow range of pressure (referred to herein as a narrow range micro pressure sensor).
- a broad range micro pressure sensor that has high sensitivities over a broad range of pressures, as is referred to herein as a broad range micro pressure sensor.
- Two types of broad range micro pressure sensors are described, a broad range micro pressure sensor 10 and a stacked broad range micro pressure sensor 100.
- the micro pressure sensor 10 has high sensitivity to pressure changes and can serve as an element of a module stage in a stack of module stages (stages) of a broad range micro pressure sensor 100 (FIG. 4).
- the micro pressure sensor 10 includes a chamber 20 that is compartmentalized into plural compartments 21 a-21g by plural membranes 18a-18f.
- the micro pressure sensor 10 includes a sensor body 11 having two walls 13a, 13b along a fluid flow direction, end caps 16a, 16b that are opposite to each other along a direction perpendicular to the fluid flow direction, and two walls, e.g. front and back walls (not shown in the views of FIGS. 1-3) that are orthogonal to two fixed end caps 16a, 16b and walls 13a, 13b.
- the walls 13a, 13b and 16a, 16b and the front and back walls define the single chamber 20.
- each of compartments 21a-21g that provide the single chamber 20 is further divided into plural sub- compartments two of which, e.g., sub-compartments 23a-23b are shown (see also FIG. 6 A), as well as, other sub-compartments not shown in FIG. 1, but shown in FIG. 6A.
- Each of the plural sub-compartments 23a-23b (as well as sub-compartments not shown in FIG. 1) is compartmentalized by membrane layers (membranes) 18a-18f.
- membrane layers membrane layers
- sub-compartments 23 a will have membranes having different surface areas and hence volumes than sub-compartments 23b. However, in some embodiments surface areas and hence volumes can be the same provided that other measures are taken to change the sensitivity of the membranes over compartments 23a, 23b to pressures.
- Membranes 18a-18f are anchored between the two end walls 16a, 16b and the front and back walls and on walls, e.g., 17a, 17b that divide the chamber 20 into the plural sub-compartments 23a-23b. While the membranes 18a-18f separate the chamber 20 into plural compartments 21 a-21g, the walls (two of which) 17a, 17b are shown and other walls (not shown in FIG. 1, but shown in FIG. 6A) separate each compartment into plural sub-compartments two of which sub-compartments 23a-23b are shown in FIGS. 1 -3.
- a first set of ports 12a-12c are disposed through wall 13a for fluid access into each of compartments 21b, 21d and 21f, respectively.
- a second set of ports 14a-14d are disposed through wall 13b for fluid access into each of compartments 21 a, 21 c, 21 e and 21g, respectively.
- each compartment 21 a-21b includes a port either from the first set of ports 12a-12c or from the second set of ports 14a-14d, but not both, defined in the respective walls.
- the compartment 21 a includes the port 14a in the wall 13b, while the port of the wall 13a in the region of compartment 21 a is solid, without any opening.
- sub-compartments 23a-23b will provide different degrees of sensitivity within a single compartment to different pressures and pressure ranges.
- the ports are shown on opposing sides. Ports being on opposing sides is desirable in many embodiments, but is not required. In other embodiments, the ports can be on adjacent sides or indeed on the same side provided that ports acting as inlets or input ports are separated from ports acting as outlets or output ports, by such ports being coupled to different vessels that provide the fluid whose pressure is being measured and the reference. A compartment would have but one inlet or one outlet but not both.
- this arrangement of a solid wall at one end and a first one of the first set of ports or a first one of the second set of ports at an opposing end is alternated, such as shown for adjacent compartment 21b having port 12a in wall 13a with wall 13b being a solid wall at the region of compartment 21b.
- the compartments 21 a- 21g are fluidic-ally sealed from each other, but each of the sub-compartments within a sub-compartment are fluidic-ally coupled.
- Two compartments 21 a and 21 g at the opposite ends of the micro pressure sensor 10 have walls provided by the fixed walls 16a, 16b of the body and a corresponding membrane.
- Intermediate compartments 21b- 21 f between the compartments have walls provided by two adjacent membranes with the micro pressure sensor 10 having at least one and generally many intermediate compartments, each of which intermediate compartment walls are provided by two membranes 18a-l 8f.
- the micro pressure sensor 10 can sense changes in pressure from a rest position as is illustrated in FIG. 1. Changes in fluid pressures of, e.g.
- micro pressure sensor 10 typically gases or in some instances liquids are detected and the micro pressure sensor 10 is constructed with materials, the selection of which takes into consideration the type of fluid that the micro pressure sensor 10 will be configured to sense pressure of as well as a range of pressures over which the micro pressure sensor 10 will have suitable sensitivity.
- pressures are relative to ambient pressure of ambient air.
- other references may be used.
- broad range micro pressure sensors are relative to a narrow range micro pressure sensor. While the discussion below will focus on broad range micro pressure sensors, it would be helpful to first define a narrow range micro pressure sensor, and to discuss general features and operational characteristics common to both narrow and broad range micro pressure sensors.
- a narrow range micro pressure sensor is comprised of one or more standard pressure sensor chambers 20 that have identical pressure sensor characteristics, i.e., sensitivity over a narrow pressure range.
- a standard pressure sensor chamber 20 is defined as a single chamber that has at least two compartments (and which could have many such compartments) with each of the compartment being identical in pressure sensing characteristics.
- One way for compartments to be identical in pressure sensing characteristics is by having the compartments being identical in size, volume, elastic characteristics of the membranes, and characteristics of electrodes.
- a narrow range pressure sensor will have high sensitivity over a defined, yet relatively limited, i.e., narrow, range of pressure in comparison to the broad range micro pressure sensor 10.
- the range of sensitivity to pressure is based on the size and volume characteristics of compartments, elastic characteristics of the membranes (Young's modulus and thickness), and characteristics of electrodes (pattern, thickness, etc.) that affect changes in capacitance measured between electrodes of the micro pressure sensor.
- the micro pressure sensor 10 can have fewer membranes and thus fewer compartments or can be extended with additional intermediate membranes having additional membranes as each compartment can be viewed as a module (see, FIGS. 4-6), with the micro pressure sensor 10 formed of a stack of such modules, as described further below.
- Each membrane 18a-18f has an electrode (not explicitly shown in FIG. 1 attached over a major surface of the membrane 18a-18f.
- the electrodes are connected to a capacitance measurement circuit (see FIGS. 2, 3) that delivers voltages to the electrodes according to the type of capacitance measurement circuit employed.
- a capacitance measurement circuit see FIGS. 2, 3
- an AC waveform can be used and the capacitance is measured using frequency domain techniques.
- a DC waveform is used to measure capacitance using time domain techniques.
- each membrane 18a-18f at rest is substantially parallel to the end walls 16a, 16b and the compartments 21 a-21 g can have the same nominal volume Vi, with the membranes 18a- 18f in this implementation being separated by equal distances (thickness of the wall portions).
- the membranes 18a- 18f and thus electrodes flex, changing the volume of the respective compartments and more particularly, the distance separating pairs of electrodes on such membranes 18a-18f. These changes in distance separating pairs of electrodes cause changes in capacitance between pairs of adjacent electrodes, as shown for 18a, 18b in FIGS. 2, 3.
- a capacitance characteristic is provided by a pair of adjacent electrodes that are separated by a dielectric, e.g., contents of a compartment (i.e., the fluid) and/or the dielectric property of the membrane.
- a capacitor is effectively provided by the combination of a pair of electrodes on a pair of adjacent membranes that are separated by distance provided from the respective compartment.
- a capacitance characteristic of such effective capacitor is determined by the dielectric constant provided by one of the pair of adjacent membranes, the dielectric of the fluid in the compartment, the area of the electrodes and distance that separates the electrodes, e.g., generally at least approximated by a formula for a parallel plate capacitor, given as:
- C is the capacitance, in farads
- A is the area of overlap of the two electrodes, in square meters
- s r is the dielectric constant of the material between the electrodes (sum of dielectric constants of a membrane and fluid);
- ⁇ is the electric constant ( ⁇ 3 ⁇ 4 8.854x 10-12 F-m-1);
- d is the separation between the plates, in meters.
- a controller (see FIGS. 2, 3) that is either part of a capacitance measurement circuit or a separate circuit references a table/algorithm to convert measured capacitance units into pressure units. Many techniques can be used to measure and detect changes in such capacitance over a bulk capacitance provided by the micro sensor 10 while in a rest condition.
- each of the compartments 21a-21g can have similar nominal volumes V e . In such embodiments,
- the distance between the membrane 18a in its nominal position and the end wall 16a or between the membrane 18f in its nominal position and the end wall 16b is about 50 microns.
- the compartments 21a-21g can also have different sizes. The sizes can be chosen based on, e.g., manufacturing, power consumption, and application considerations.
- the micro pressure sensor 10 can have a length of about 1.5 mm, a width of about 1.5 mm, a total height (the cumulative height of different compartments) of 0.05mm, and a total volume of about
- the micro pressure sensor 10 may use less material, and thus is subject to less stress.
- the micro pressure sensor 10 has a size in the micron to millimeter scale, and can provide wide ranges of pressure measurements.
- the ports can be on adjacent sides or indeed on the same side, provided that ports acting as inlets or input ports are separated from ports acting as outlets or output ports, by such ports being coupled to different vessels that provide the fluid whose pressure is being measured and the reference.
- the described micro pressure sensor 10 is a capacitance type of sensor. Sensing occurs in either of two alternating operations of a fluid overpressure and fluid under pressure in the chamber 20 of the micro pressure sensor 10.
- FIG. 2 with application of an overpressure (higher pressure at ports 12a, 12b and 12c acting as inlets compared to a reference at ports 14a-14d acting as outlets) from a fluid source 26, end compartments 21 a and 21g are shown compressed as are the intermediate compartments 22c, 21 e.
- the applied overpressure is sufficiently high to cause flexing of portions of membranes 18a-18f that cover the sub- compartments 23a in each compartment 21 a-21g, but the applied overpressure is not sufficiently high to flex portions of the membranes 18a-18f covering the sub-compartments 23b in each compartment 21 a-21g.
- the surface area of the membranes 18a-18f covering each of the sub- compartments 23 a will be large enough to allow flexure of the membranes in response to the overpressure applied to ports 12a, 12b and 12c acting as inlets, but the surface area of the membranes 18a-18f covering each of the sub -compartments 23b being smaller and thus the membranes are effectively suffer over sub-compartment 23b than sub-compartment 23a.
- the overpressure in sub- compartment 23b is insufficient to cause any or at least a significant flexure of the membranes 18a-18f in response to the overpressure applied to ports 12a, 12b and 12c acting as inlets.
- the compression occurs in the end compartments 21 a, 21g when membranes 18a, 18f move towards respective end walls 16a, 16b and for the intermediate compartments, 22c, 21 e when adjacent membranes 18b, 18c and 18d, 18e move towards each other occupying space of the adjacent compartments 22c, 21 e due to displacement of air from those compartments 22c, 22e.
- the movement of these membranes 18a and 18f reduces the volume of the respective end compartments 21 a, 21g and intermediate compartments 21 c, 21 e to discharge fluid (gas or liquid) from those compartments into the ambient (or reference) in those portions of the compartments that are part of the sub-compartment 23a, but not sub-compartments 23b.
- compartments 21b, 21 d, 21f are over pressured when respective sets of membranes 18a, 18b; 18c, 18d; and 18e, 18f, move away from each other to expand the respective compartment volumes that are part of the sub- compartment 23a, but not sub-compartment 23b.
- the inlets 12a-12c into the sub- compartments 23 a and 23b are fed a fluid under a pressure higher than the reference pressure (ambient in this case) causing the membranes 18a-18f to flex as shown. That is, when a fluid is fed into port 12a (acting as an input port), adjacent membranes 18a, 18b defining compartment 21b will flex or deform away from each other towards adjacent compartments 21a and 21 c, displacing air from those compartment 21 a, 21 c through ports 14a, 14b (acting as output ports) into the ambient. Similarly, the other membranes will likewise flex or bend upon fluid at pressure being introduced into the remaining ports 12b, 12c.
- the increased overpressure will cause additional flexure of the membranes 18a-18f covering the sub-compartments 23a, but will start flexing the membranes 18a-18f portions over sub-compartments 23b in response to the increased overpressure applied to ports 12a, 12b and 12c acting as inlets.
- FIG. 2 A shows the arrangement of FIG. 2, (see FIG. 2 for description of reference nos. not mentioned) but with an overpressure that is greater than the overpressure in FIG. 2, which is sufficient to cause the membranes 18a-18f covering each of the sub-compartments 23a to completely flex in response to the overpressure applied to ports 12a, 12b and 12c acting as inlets, and being sufficient to cause the membranes 18a-18f covering each of the sub-compartments 23b to flex substantially more than that of FIG. 2, over sub-compartments 23b.
- FIG. 3 in an under-pressure (lower pressure than a reference, e.g., down to a vacuum pressure), at ports acting as inlets 12a-12c compared to a reference at ports acting as outlets, end compartments 21 a, 21g are shown expanded as are the intermediate compartments 21c and 2 Id.
- the applied under-pressure is sufficiently low to flex portions of membrane 18a-18f that cover the sub-compartment 23a, but the applied under-pressure is not sufficiently low to flex portions of membranes 18a-18f covering the sub-compartment 23b.
- the expansion occurs in the end compartments 12a, 21g when membranes 18a, 18f move away from end walls 16a, 16b and for compartments 21 c, 21 d when adjacent membranes 18b, 18c and 18 move away from each other.
- the movement of these membranes increases the volume of the respective end compartments 21a, 21g and intermediate compartments 21 c, 21 d, in those portions of the compartments that are part of the sub-compartment 23a, but not sub-compartment 23b due to the charge of fluid (gas or liquid) into the compartments coupled to the ambient or reference.
- adjacent compartments 21b, 21d and 21f are discharged when respective sets of membranes move towards each other to reduce the respective compartment volumes in those portions of the compartments that are part of the sub- compartment 23a, but not sub-compartment 23b.
- the ports 12a-12c into the sub- compartment 23a are coupled to a fluid source 27 that is at a pressure lower than the reference pressure (ambient in this case) causing the membranes to flex, as shown. That is, when a fluid at an under pressure is fed into port 12a, adjacent membranes 18a, 18b defining compartment 21b will flex or deform towards each other away from adjacent compartments 21 a and 21 c, causing ambient air to enter those compartments 21 a, 21 c through ports 14a, 14b from the ambient in those portions of the
- the other membranes 18c, 18d and 18e, 18f will likewise flex or bend towards each other in response to the fluid at an under pressure being introduced into the remaining ports 12b, 12c, by ambient entering compartments 21 e, 21 g through ports 14c-14d in those portions of the compartments that are part of the sub- compartment 23a, but not sub-compartment 23b.
- the micro pressure sensor 10 discussed above thus comprises multiple membranes 18a-18f each anchored between two fixed walls 13a, 13b and two fixed walls not shown in those views.
- the fixed walls 13a, 13b and the not depicted walls are body layers that form multiple compartments separated by pairs of adjacent membranes.
- the first and last ones of the compartments are formed by a membrane and a fixed wall that is part of an end cap of the body, but intermediate compartments are provided by pairs of adjacent membranes.
- Each of the compartments 21 a-21 g is divided into plural sub-compartments (sub-compartments 23a, 23b shown) and portions of the membranes 18a-18f covering those portions of the sub-compartments 23a and 23b will flex according to the extent of the overpressure or under-pressure applied to the chamber 20, as a whole.
- FIGS. 2 and 3 that show two operational states of the same micro pressure sensor 10 indicates that in a first mode, pressure higher than the reference is measured, and in a second mode pressure lower than the reference is measured. That is, when actuated, each membrane of a compartment can move in two opposite directions about a central, nominal location at which the membrane rests when it is not actuated.
- Electrodes are on the membranes 18a-18f of the micro pressure sensor 10.
- a single electrode is provided on a membrane.
- the electrodes are patterned according to the sub-compartment 23a, 23b associated with the respective portion of the membranes 18a-18f.
- the electrodes for respective sub-compartments 23a, 23b are connected in parallel to a capacitance measurement circuit 32, discussed below.
- the combination of two membranes with electrodes, separated by dielectric form capacitors.
- the capacitance of these "capacitors” is measured via conventional capacitance measurement circuits 32.
- a correlation can be provided between measured capacitance and pressure such as by a controller 34.
- Various implementations are possible.
- Micro pressure sensors having the above described features can be manufactured using various methods such as MEMS processing techniques and so- called roll to roll (R2R) processing.
- the materials for a micro pressure sensor 10 are chosen based on the features to be provided by the micro pressure sensor 10 and the method of manufacturing of the micro pressure sensor 10. Below are some criteria for choosing the materials of the different parts of micro pressure sensor 10.
- the material used for the body may be defined by the requirements. In general, the material needs to be strong or stiff enough to hold its shape to produce the compartment volume. In some implementations, the material is etchable or photo sensitive so that its features can be defined and
- the material interact well, e.g., adheres, with the other materials in the sensor.
- the material is electrically non-conductive. Examples of suitable materials include SU8 (negative epoxy resist), and PMMA (Polymethyl methacrylate) resist.
- Membrane - The material for this part forms a tympanic structure that charges and discharges fluid in the chamber. As such, the material is required to bend or stretch back and forth over a desired distance and have elastic characteristics.
- the membrane material is impermeable to the fluids of interest, including gas and liquids, is electrically non-conductive, and can have either a low or a high breakdown voltage characteristic. Examples of suitable materials include silicon nitride, and Teflon. Others are possible.
- Electrodes - The material of the electrodes is electrically conductive. Because the electrodes do not conduct significant amounts of current, the material can have a high electrical sheet resistance, although the high resistance feature is not necessarily desirable.
- the electrodes are subject to bending and stretching with the membranes, and therefore, it is desirable that the material is supple to handle the bending and stretching without fatigue and failure.
- the electrode material and the membrane material adhere well, e.g., do not delaminate from each other, under the conditions of operation. Examples of suitable materials include very thin layers of gold and platinum. Others are possible.
- Electrodes The voltages from the capacitance measurement circuits are conducted to the electrode on each membrane of each compartment. Electrically conducting paths to these electrodes can be built using conductive materials, e.g., gold and platinum.
- a sacrificial filling material e.g., polyvinyl alcohol (PVA)
- PVA polyvinyl alcohol
- solvents are used in the manufacturing process, which may place additional requirements on the various building materials of the micro pressure sensor. It may be possible to print some of the electrical circuit components onto the membranes. In general, while certain materials have been specified above, other materials having similar properties to those mentioned could be used.
- the broad range micro pressure sensor 100 includes plural (at least two and can be many more) here three modules 102a-102c that are stacked one over the other and spaced by spacer layers 104a-104b. Each of the three modules 102a-102c is provided to be highly sensitive to a specific range of pressures.
- the modularized broad range micro pressure sensor 100 also has end caps 101a, 101b. End cap 101a is partially broken away to reveal an underlying electrode.
- the modularized broad range micro pressure sensor 100 differs from the modularized broad range micro pressure sensor 10 (FIGS. 1 -3) in that the
- modularized broad range micro pressure sensor 100 has the plural module stages (stages) 102a-102c. Operating principals however are similar. Each stage 102a-102c is comprised of plural compartments, referred to here as modular layers 105a-105c respectively. Each of the modular layers 105a-105c has plural sub-compartments. Modular layer 105a has plural sub-compartments 23a-23b (twelve identical versions of 23b) as shown in FIG. 6A; modular layer 105b has plural sub-compartments 24a- 24c (two identical versions of 24a, 6 identical versions of 24b and 2 identical versions of 24c) as shown in FIG.
- modular layer 105c has plural sub-compartments 25a-25d, (two identical versions of 25a, 25b, 25c and 5 identical versions of 24d) as shown in FIG. 6C, respectively.
- the sub-compartments in each the of modular layers 105a-105c are different in number and configuration (see FIGS 6A-6C).
- the modularized broad range micro pressure sensor 100 (modularized micro pressure sensor 100) has high sensitivity (relatively large change in capacitance over a broad range of pressure) in comparison to a narrow range micro pressure sensor discussed in the above incorporated by reference patent application.
- Each of the three stages 102a-102c is comprised of at least one and generally several or many module layers 105a-105c.
- each stage 102a-102c is shown comprised of several module layers 105 a- 105 c.
- module layers 105 a- 105c are also referred to as repeatable layers.
- a first portion of the module layers generally 105 have a pair of ports 107a (referenced for one of the module layers 105) on one side of the micro pressure sensor 100 (similar to ports 12a-12c FIG. 2), and a second portion of the module layers 105 have a pair of ports (not shown) on an opposite side (back) of the micro pressure sensor 100 (similar to ports 14a-14d FIG. 2).
- Each module layer 105a-105c thus has a pair of openings in one of here, four walls.
- the module layers 105a-105c are alternated such that the opening in one module is on a side of the micro pressure sensor 100, which is directly opposite the side having the opening in an adjacent module layer.
- a module layer generally 105 includes a body layer 111a that supports a membrane 111b that carries an electrode 111c and which provides (together with another membrane on another module) a compartment.
- the body layer 111a has a pair of ports 107b.
- the electrode 111c has a tab 111 d for connection by metal vias to the measurement circuit.
- Holes 111 e are provided through peripheral portions of the body 111a.
- Each module 105 has one hole that contacts through the metal via one tab 11 Id. A stack of four modules 105 thus is used to contact through the metal vias each of the four holes.
- the electrode 11 lc in a top module e.g., module 105a contacts through the metal via the first hole and the electrode 11 lc in a fifth module (first one of the modules 105b in stage 102b) from the top module 105a in the stack contacts through the metal via the hole in the corresponding location of the fifth module as the hole in the first module.
- the electrodes can be a pre-prepared sheet to be attached to the other elements, the electrodes can be formed directly onto those elements, e.g., by printing or with other techniques discussed below.
- multiple, e.g., two, three, or any desired number of, modules and module layers are stacked on top of each other to form multiple intermediate compartments in a modularized, stacked micro pressure sensor 100.
- each membrane is separated by the body and each body is separated by a membrane.
- the end caps are placed on each of the top and bottom ends of the stack of modules so that the end caps on the modules form two fixed end walls of the modularized, stacked micro pressure sensor, as shown in FIG. 4.
- Each of the three stages 102a-102c are configured to be highly sensitive to a specific range of pressures. That is one stage, e.g., stage 102a is highly sensitivity to pressure in a given pressure range, e.g., Rl , whereas stages 102b and 102c provide a relatively small contribution to sensitivity to pressures in the pressure range Rl, but each of the stages 102b-102c are highly sensitivity to pressures in given pressure ranges R2 and R3 respectively, while providing a relatively small contributions to sensitivity to pressure changes outside of their respective pressure ranges.
- stage 102a is highly sensitivity to pressure in a given pressure range, e.g., Rl
- stages 102b and 102c provide a relatively small contribution to sensitivity to pressures in the pressure range Rl
- each of the stages 102b-102c are highly sensitivity to pressures in given pressure ranges R2 and R3 respectively, while providing a relatively small contributions to sensitivity to pressure changes outside of their respective pressure ranges.
- FIG. 4 Also shown in FIG. 4 are a capacitance measurement circuit and controller (as discussed in FIG. 2) that are coupled to electrodes (represented by lines 106a, 106b) of the broad range micro pressure sensor 100, as shown.
- Vias 108a-108d exist on edges of each of the module layers 105. Internally, vias 108a and 108b are connected to provide effectively the connection represented by line 106a, and vias 108c and 108d are connected and provide effectively the connection represented by line 104b.
- each of the stages 102a- 102c can be electrically modeled 120a'-120c' as a capacitor having a bulk capacitance value Cb corresponding to a quiescent or rest position of the membrane (pressure difference of zero) and a variable capacitance value C v corresponding to a flexed position of the membranes in response to a non-zero pressure difference.
- each of the models 120a'-120c' are shown as having the bulk capacitance value Cb and variable capacitance value C v corresponding each module layer 105 in the respective stages.
- Each of the capacitors are electrically connected in parallel. Capacitors connected in parallel have a total capacitance that is the sum of capacitances of the individual capacitors.
- micro pressure sensor 100 can be used to provide the micro pressure sensor 100. Fundamentally, common to all approaches is fabrication of plural modules that have corresponding high sensitivities to different pressure ranges. Such plural modules that have corresponding high sensitivities can be configured to have plural sub- compartments (each of at least two sub-compartments) having high sensitivities to different pressure ranges.
- One mechanism to provide high sensitivity over broader ranges of pressure for a given standard size chamber is make the membranes of different stiffness relative to each other. Described now is a mechanism to provide membranes with different 'effective' stiffness by providing different aperture sizes within a compartment to make the membrane effectively more or less stiff. In general, the stiffer the membrane the more pressure would be required to flex the membrane.
- FIGS. 6A-6C show three different patterns for forming body layers to provide sub-compartments within a body layer.
- Over groups of the body layers e.g., one or more body layers in a stack
- the membranes carry electrodes (both not shown) that together with the body layer provides a module layer 105 (as shown in FIG. 5).
- the body layer is patterned to provide a complex pattern of sub-compartments. While the complex pattern of each compartment can vary, these exemplary patterns shown in FIGS. 6A-6C depicts general concepts that could be followed in choosing patterns.
- each sub-compartment is enclosed in a frame of body layer material, that is each sub compartment is substantially surrounded by body layer material, but for passages into such sub-compartments.
- a frame of body layer material provides suitable surfaces by which membranes can adhere to the body layer.
- FIG. 6A is an example of a complex partem of sub-compartments of two different size areas.
- One sub-compartment 23a is a large sub-compartment and the others are twelve smaller sub-compartments 23b of substantially the same area relative to sub-compartment 23a.
- the large sub-compartment 23a and four of the relatively smaller sub-compartments 23b are fluidly connected to the port 107a, and the remaining eight relatively smaller sub-compartments 23b are fluidly connected to the port 107b.
- FIG. 6B is an example of a complex pattern of sub-compartments of three different size areas.
- Two sub-compartments 24a are large sub-compartments, four sub-compartments 24b are smaller relative to sub-compartments 24a and two other sub-compartments 24c are smaller relative to sub-compartments 24b.
- one of the large sub-compartments 24a, three of the smaller sub-compartments 24b and one of the still smaller sub-compartments 24c are fluidly connected to one of the ports 107a and the remaining large sub-compartment 24a, and three smaller sub- compartments 24b and sub-compartment 24c are fluidly connected to port 107b.
- FIG. 6C is an example of a complex partem of sub-compartments of four different size areas.
- Two sub-compartments 25a are relatively large sub- compartments
- two sub-compartments 25b are smaller relative to sub-compartments 25a
- two other sub-compartments 25c are smaller relative to sub-compartments 25b
- four other sub-compartments 25 d are smaller relative to sub-compartments 25 c.
- one of the large sub-compartments 25a and one of each smaller sub compartments 25b, 25c and 25d are fluidly connected to one of the ports 107a and the remaining sub-compartments are fluidly connected to port 107b.
- the sub-compartments can be patterned entirely through the body layer material, i.e., open apertures, i.e., holes (that are covered by membranes) in providing module layers, in some instances, it may be required or desired to only partially pattern through the body layer material, providing shallow regions (that are covered by membranes) rather than holes within body layer, with body layer material remaining on a backside of the module.
- open apertures i.e., holes (that are covered by membranes)
- body layer material i.e., open apertures, i.e., holes (that are covered by membranes) in providing module layers
- a standard size compartment can be defined. While a standard size compartment could be of any size, for discussion herein it is nominally 1.5 mm long by 1.5 mm wide by 50 microns high. Each complex patterned compartment is formed from the micro sensor body material by patterning that material to form plural sub compartments that define the particular complex pattern within the standard size compartment (examples of which were shown in FIGS. 6A- 6C). That is, within a "standard size compartment" are plural sub-compartments that have selected sizes (surface area) with respect to the reference standard size compartment.
- the complex pattern compartment can be any pattern that leaves body material within portions of the otherwise standard size compartment forming plural sub compartments within the standard size compartment.
- the membranes carry electrodes and a compartment is bounded by a pair of membranes each of which carries a corresponding electrode.
- fluid e.g., air enters through ports 107a, 107b filling all of the sub -compartments in the complex pattern compartment, and all portions of the compartment experience the same pressure.
- the membranes of each compartment will flex (as in FIGS. 2, 3).
- capacitance will change according to the amount of flexure experienced by the membranes.
- FIG. 6A assume that the pattern of FIG. 6 A is used in the module layer 105 a that is part of the stage 102a (FIG. 4) and the module 105a is sensitive over a range of 2 to 4 psi.
- the amount of flexure of the membrane 105b will be relatively minimal. This is because the sizing (surface area) of the sub-compartments 23a and 23b is selected to be minimally responsive to pressures below 2 psi.
- the sensitivity (change in capacitance vs. change in pressure) can be modeled knowing the Young's modulus of the membrane/electrode combination, surface area of the aperture, dielectric constants of material between pairs of electrodes, size of the electrodes, and height of the aperture, generally as discussed above. At or slightly above 2 psi, the portion of the membrane over the sub-compartments 23a, 23b will start to flex.
- the amount of flexure of the membrane 105b at or slightly above 2 psi over the sub-compartment 23 a will substantially more than the amount of flexure over the sub-compartments 23b.
- the relative amounts of flexure would be related to differences in surface area of membrane portions over the sub-compartments 23a and 23b, because the membrane 105b is affixed to the body layer along the frame of the body as well as interior portions, thus effectively providing individual membranes over each of the sub-compartments 23 a, 24a.
- each distinct pair of electrodes on membranes covering provide effectively a fixed or bulk capacitance and a variable capacitance in parallel.
- Each module and each sub-compartment likewise effectively a fixed or bulk capacitance and a variable capacitance all of which are in parallel and thus add together to provide a total fixed or bulk capacitance and total variable capacitance.
- Design considerations to consider include the provision that no sub-compartment should exhibit a maximum pressure that will cause the membrane to flex and exceed the elastic limit of the material of the membrane.
- Each stage 102a-102c therefore can be comprised of plural module layers 105 and within a given stage 102a- 102c, the plural module layers 105 can be of one of the types discussed in FIGS. 6A-6C.
- stage 102a is comprised of plural module layers 105 of the type discussed in FIG. 6A
- stage 102b is comprised of plural module layers 105 of the type discussed in FIG. 6B
- stage 102c is comprised of plural module layers 105 of the type discussed in FIG. 6C.
- Other arrangements and configurations may be possible.
- FIG. 7 shows the modularized broad range micro pressure sensor 100 of FIG. 4 with the top cap and spacer layer, and the membranes/electrodes removed from the first few module layers 105 to illustrate the complex patterned body layers. Stages 102a-102c are indicated spaced by spacer layers 104b and 104c end cap 101b and front ports 107 a.
- FIG. 8 shows the modularized broad range micro pressure sensor 100 of FIG. 4 with the module layers 105 (FIG. 4) removed, but showing the end caps 101 a, 101b and the spacers 104a-104c.
- the modularized broad range micro pressure sensor 100 thus can be fabricated from "standard sized” compartments (with respect to FIG. 1) of "standard sized” compartments comprised of stacked module layers 105, but which has a high pressure sensitivity over an extended pressure range, i.e., a "high sensitivity micro pressure sensor” by having at least some of the plural module layers patterned with complex compartments that again are in reference to the "standard sized” compartment, as discussed above.
- each set of module layers that form a module are comprised of an identical type of complex patterned compartment.
- Each membrane of the micro pressure sensor 100 moves in two opposite directions relative to its central, nominal position.
- the membrane flexes to either expand or reduce a distance itself and an adjacent membrane and thus between a pair of electrodes carried by itself and the adjacent membrane, and concomitant therewith either increasing or decreasing a capacitance value of an effective capacitor provided between the two electrodes.
- the membrane travels a distance less than, e.g. , half of, the height of the compartment. As a result, the membrane experiences less flexing and less stress, leading to longer life and allowing for greater choice of materials.
- each one of the membranes carries but one electrode, and capacitance is being sensed, these capacitors and more specifically these electrodes can be connected, such that the capacitors are connected in parallel. Capacitors connected in parallel add in capacitance.
- the modularized broad range micro pressure sensor 100 will have a higher bulk capacitance and a higher range of variable capacitance, and thus greater sensitivity (change in pressure per change in capacitance) compared a single capacitor formed by a single membrane and pair of electrodes.
- Exemplary values for sensitivity can be such as 0.02 pf capacitance change per 0.05 psi change over a range of 0.0 to 100 psi.
- Other ranges and sensitivities can be provided by different selections of materials and dimensions of a compartment and sub compartments, as well as providing more or few module layers per module and more or fewer modules per modularized broad range micro pressure sensor 100.
- the membranes, the end caps, and the body can have the same dimensions, and the electrodes can have smaller dimensions than the membrane or the other elements.
- the membrane has a dimension of about microns by microns to about millimeters by millimeters, and a thickness of about 5 microns.
- the body has an outer dimension of about microns by microns to about millimeters by millimeters, a thickness of about 50 microns, and an inner dimension of about microns by microns to about millimeters by millimeters.
- the thickness of the body defines the nominal size of the compartment (similar to compartments FIG. 1).
- the electrodes have dimensions that substantially correspond to inner dimensions of the body.
- the electrodes have a surface area of about 2.25 mm 2 and a thickness of about 0.01 microns (100 Angstroms).
- An assembled module layer was shown in FIG. 4A.
- FIG. 9 a table of exemplary calculated values is shown that has for a standard micro pressure sensor (from the incorporated by reference application) calculated capacitance values in pico-farads for one module and seven module micro pressure sensors, with separations (distances between electrodes) and corresponding pressures expressed in cm of water. At 50 microns, separation (resting state) the capacitance of one capacitor is 0.38 pF and for seven 2.26 pF, with 0.00 cm of water pressure. Similar characterizations can be provided for the micro pressure sensors 10 and 100.
- FIGS. 10 and 11 show exemplary plots for a standard micro pressure sensor (from the incorporated by reference application) with FIG. 10 plotting pressure (cm of water) vs. capacitance in pF for one and seven modules (capacitors). With seven modules, a greater range in capacitance would be provided for the same pressure range in comparison to capacitance range for one capacitor (single stage module). Similar characterizations can be provided for the micro pressure sensors 10 and 100.
- FIG. 1 1 shows that capacitance vs. pressure and separation vs. pressure to be substantially linear in the operating range of the standard micro pressure sensor (from the incorporated by reference application). Similar characterizations can be provided for the micro pressure sensors 10 and 100.
- the processing line comprises several stations, e.g., station 1 to station n (that can be or include enclosed sub-compartments) at which deposition, patterning, and other processing occurs. Processing viewed at a high level thus can be additive (adding material exactly where wanted) or subtractive (removing material in places where not wanted).
- Deposition processing includes evaporation, sputtering, and/or chemical vapor deposition (CVD), as needed, as well as printing.
- the patterning processing can include depending on requirements techniques such as scanning laser and electron beam pattern generation, machining, optical lithography, gravure and flexographic (offset) printing depending on resolution of features being patterned. Ink jet printing and screen printing can be used to put down functional materials such as conductors. Other techniques such as punching, imprinting and embossing can be used.
- the original raw material roll is of a web of flexible material.
- the web of flexible material can be any such material and is typically glass or a plastic or a stainless steel. While any of these materials (or others) could be used, plastic has the advantage of lower cost considerations over glass and stainless steel. Specific materials will be determined according to the application of the micro pressure sensor. In applications materials such as stainless steel or other materials that can withstand encountered temperatures would be used, such as Teflon and other plastics that can withstand encountered temperatures.
- stations within a roll to roll processing line are set up according to the processing required.
- the end cap and top caps could be formed on the web or plastic sheet in one implementation the end and top caps are provided after formation of the micro -pressure sensor stack, as will be described.
- the plastic web is used to support the body by a deposition of material on the web at a deposition station followed by patterning station.
- the body is formed at a forming station.
- the web having the body has a membrane deposited over the body at a station. Over the membrane is deposited an electrode at deposition station which is patterned at patterning station.
- Membrane sheet with patterned electrodes supported on the membrane are provided on the body.
- Electrical interconnects, for connecting to the electrodes on each membrane are provided by depositing conductive materials, e.g., gold, silver, and platinum layers (or conductive inks such as silver inks and the like). In some implementations some of the electrical circuit components are printed onto the membranes.
- the roll having the micro module units are diced and the micro module units are collected, assembled into stacks of micro modules, and packaged by including the end and top caps to provide the micro pressure sensor 10 or 100.
- the micro module units body and membrane with electrode and electrical connections
- the micro module units are collected, assembled into stacks of micro modules, and packaged by including the end and top caps to provide the micro pressure sensor 10 or 100.
- the end and top caps to provide the micro pressure sensor 10 or 100.
- the web of the module units into a stack of units, with electrodes provided on the membrane layer or whole layers of many units can be laminated together to produce a stack prior to being diced and packaged.
- the membrane material is required to bend or stretch back and forth over a desired distance and thus should have elastic characteristics.
- the membrane material is impermeable to fluids, including gas and liquids, is electrically non-conductive, and possesses a high breakdown voltage. Examples of suitable materials include silicon nitride and Teflon.
- the material of the electrodes is electrically conductive.
- the electrodes do not conduct significant current.
- the electrodes are subject to bending and stretching with the membranes, and therefore, it is desirable that the material is supple to handle the bending and stretching without fatigue and failure.
- the electrode material and the membrane material adhere well, e.g., do not delaminate from each other, under the conditions of operation.
- suitable materials include, e.g., gold, silver, and platinum layers (or conductive inks such as silver inks and the like).
- a release material can be used for allowing for valve movement. Suitable release materials include, e.g., the sacrificial filling material mentioned above.
- the micro pressure sensor has the membranes, which flex in operation.
- the micro pressure sensor is fabricated using roll to roll processing where a raw sheet (or multiple raw sheets) of material is passed through plural stations to have features applied to the sheet (or sheets) and the sheet (or sheets) are subsequently taken up to form parts of the repeatable composite layers (See FIG. 4) to ultimately produce a composite sheet of fabricated micro pressure sensors.
- a sheet of a flexible material such as a glass or a plastic or a stainless steel is used as a web.
- the material is a plastic sheet, e.g., Polyethylene terephthalate (PET).
- PET Polyethylene terephthalate
- the sheet and hence body layer is a 50 micron thick sheet of PET.
- Other thicknesses could be used (e.g., the sheet and body layer could have a thickness between, e.g., 25 microns and 250 microns (or greater) and the membrane, nominally 5 microns could be, e.g., being about 10% of the thickness of the body.
- the thicknesses are predicated on desired properties of the micro pressure sensor and the handling capabilities of roll to roll processing lines. These considerations will provide a practical limitation on the maximum thickness. Similarly, the minimum thicknesses are predicated on the desired properties of the micro pressure sensor to be constructed and the ability to handle very thin sheets in roll to roll processing lines.
- the layers would have thicknesses as mentioned above approximately 50 microns for the body layers and 5 microns for the membrane elements of the micro pressure sensor. However, other thicknesses are possible.
- the sheet is micro-machined using a mask or direct write to configure a laser ablation station to define or form sub-compartments for micro pressure sensor 10 or 100 (e.g. , the complex patterned sub-compartments as desired examples shown in FIG. 6A-6C), as well as alignment holes (not shown but will be discussed below). Vias are also provided for electrical connections.
- the micro -machining ablates away the materials, e.g., plastic to form the sub-compartments while leaving the frame portion of the body.
- the sheet with the defined compartment is laminated at a lamination station to a second sheet, e.g., 5 micron thick sheet of PET, with a metallic layer of Al of 100A on a top surface of the sheet.
- This second sheet forms the membranes over the bodies provided by the defined features of the sub- compartments.
- the second sheet is also machined to provide the alignment holes (not shown).
- the second sheet Prior to lamination of the second sheet to the first sheet, the second sheet is also provided with several randomly dispersed holes or view ports (not shown) over some areas that will be in alignment with the body structures. These randomly dispersed holes are used by a machine vision system to reveal and recognize underlying features of the body units on the first sheet. Data is generated by noting the recognized features in the first sheet through the random holes. These data will be used to align a third ablation station when forming electrodes from the layer over the bodies.
- the second sheet is laminated to and thus sticks (or adheres) to the first sheet in areas where there is plastic on the first sheet and plastic on the second sheet.
- a composite sheet of repeatable units of the micro pressure sensor are formed, but without electrodes formed from the layer on the membrane.
- the machine vision system produces a data file that is used by the laser ablation system in aligning a laser ablation station with a mask (or direct write) such that a laser beam from the laser ablation system provides the electrodes according to the mask, with the electrodes in registration with the corresponding portions of the bodies.
- the electrodes are formed by ablating away the metal in regions that are not part of the electrodes and conductors, leaving isolated electrodes and conductors on the sheet.
- the registration of the patterned electrodes to the body is thus provided by using the machine vision system to observe features on the front side of the laminated structure providing positioning data that the laser ablation system uses to align a laser beam with a mask, using techniques commonly found in the industry.
- the composite sheet is fed to the laser ablation station, to form the electrodes by ablating the 100 A 0 Al layer deposited on the second sheet that formed the membrane.
- the composite sheet is patterned according to the mask to define the electrodes over corresponding regions of the body.
- the ablation station ablates away metal from the metal layer leaving isolated electrodes on the sheet.
- a jig (not shown) that can comprises vertical four posts mounted to a horizontal base is used to stack individual ones of the cut dies.
- an end cap e.g., a 50 micron PET sheet with a metal layer
- the repeatable unit is spot welded (applying a localized heating source) to hold the unit in place on the jig.
- the stack is provided by having ports on one side of the stack and ports on the other of the stack, and staggered resulting from arrangement of the valves so as to have a solid surface separating each of the ports in the stack (See FIG. 6).
- a top cap (not shown) can be provided.
- the stack unit is sent to a lamination station not shown, where the stack is laminated, laminating all of the repeatable units and caps together.
- the end cap and top cap can be part of the packaging as well. Otherwise sets of repeatable units can be laminated or welded in pairs. Other stacking techniques for assembly are possible with or without the alignment holes.
- FIGS. 14 A, 14B details of via conductors to interconnect the patterned electrodes on the modules generally 105 as above are shown.
- the via conductors are castellated structures, i.e., with relatively wide areas contacting electrode tabs and relatively narrow areas through holes in the electrode. This arrangement is provided by having the holes in the body portions larger than the holes through the electrode portions. This can be accomplished during the patterning stages of the body and the electrodes respectively.
- the via conductors are formed by introduction of the conductive inks mentioned above into the holes.
- pressure modules are illustrated in a stack other arrangements may be possible, including pressure modules adjacent to each other and spaced from each other, provided that the pressure modules are outfitted with corresponding end caps and have inlets and outlets being fed from a common pressure source and a common reference.
- the electrodes on membranes can be patterned to correspond to underlying patterned sub-compartments (with concomitant increase in the number of
- capacitances that need to be measured and interconnected can be single membrane or can be divided into individual membranes corresponding to the underlying patterned sub-compartments.
- Other embodiments are within the scope of the following claims.
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Abstract
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CA3081244A CA3081244A1 (en) | 2017-10-31 | 2018-10-22 | Broad range micro pressure sensor |
EP18873195.4A EP3704457A4 (en) | 2017-10-31 | 2018-10-22 | Broad range micro pressure sensor |
CN201880084772.4A CN111656150B (en) | 2017-10-31 | 2018-10-22 | Wide-range micro-pressure sensor |
JP2020524073A JP2021501324A (en) | 2017-10-31 | 2018-10-22 | Wide range micro pressure sensor |
AU2018358839A AU2018358839A1 (en) | 2017-10-31 | 2018-10-22 | Broad range micro pressure sensor |
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US201762579239P | 2017-10-31 | 2017-10-31 | |
US62/579,239 | 2017-10-31 |
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PCT/US2018/056828 WO2019089250A1 (en) | 2017-10-31 | 2018-10-22 | Broad range micro pressure sensor |
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US (2) | US11046575B2 (en) |
EP (1) | EP3704457A4 (en) |
JP (1) | JP2021501324A (en) |
CN (1) | CN111656150B (en) |
AU (1) | AU2018358839A1 (en) |
CA (1) | CA3081244A1 (en) |
WO (1) | WO2019089250A1 (en) |
Cited By (1)
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CN110874502A (en) * | 2019-11-11 | 2020-03-10 | 中国人民解放军国防科技大学 | Aerospace product reliability assessment method based on multi-stage test data reduction |
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KR102282478B1 (en) * | 2021-05-26 | 2021-07-27 | 국방과학연구소 | Optimization method for unit panel size of load measurement panel |
CN113701939B (en) * | 2021-08-30 | 2023-10-27 | 北京京东方技术开发有限公司 | Pressure sensor, manufacturing method thereof and pressure sensing device |
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US20190127213A1 (en) | 2019-05-02 |
US20210323808A1 (en) | 2021-10-21 |
EP3704457A1 (en) | 2020-09-09 |
JP2021501324A (en) | 2021-01-14 |
EP3704457A4 (en) | 2021-07-21 |
AU2018358839A1 (en) | 2020-05-21 |
US11046575B2 (en) | 2021-06-29 |
CN111656150B (en) | 2022-05-03 |
CA3081244A1 (en) | 2019-05-09 |
CN111656150A (en) | 2020-09-11 |
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