CN216899367U

CN216899367U - Variable capacitance structure and pressure sensor

Info

Publication number: CN216899367U
Application number: CN202220521889.8U
Authority: CN
Inventors: 吕萍; 胡维
Original assignee: Memsensing Microsystems Suzhou China Co Ltd
Current assignee: Memsensing Microsystems Suzhou China Co Ltd
Priority date: 2022-03-11
Filing date: 2022-03-11
Publication date: 2022-07-05
Anticipated expiration: 2032-03-11

Abstract

The utility model relates to a variable capacitance structure and a pressure sensor, wherein the variable capacitance structure comprises: the variable capacitor comprises a substrate and at least one electrode pair arranged in the thickness direction of the substrate, wherein each electrode pair comprises a first electrode and a second electrode, a first groove is formed between the first electrode and the second electrode, at least one side of each electrode pair is provided with a second groove, and when the first groove is communicated with external gas and the pressure in the first groove is changed, the distance between the electrode plates between the first electrode and the second electrode forming each electrode pair is changed, so that the variable capacitor is formed.

Description

Variable capacitance structure and pressure sensor

Technical Field

The utility model relates to the field of sensors, in particular to a variable capacitor structure and a pressure sensor.

Background

A Micro-Electro-Mechanical System (MEMS) pressure sensor is a Micro-electromechanical sensor which is the earliest and has a large market share, and is widely applied to the fields of consumer electronics, medical treatment, automobiles, industrial control and the like. Piezoresistive pressure sensors and capacitive pressure sensors are two types of MEMS pressure sensors. The piezoresistive pressure sensor has the advantages of high sensitivity, low power consumption, high linearity and the like, but has the biggest defect of temperature drift and sensitivity to temperature, and because the resistor is formed by adopting a semiconductor doping process, the piezoresistive pressure sensor is easily influenced by the temperature; compared with the piezoresistive type, the capacitance type pressure sensor and the like have the greatest advantage of low temperature drift, because the capacitance type pressure sensor outputs a signal by detecting the capacitance change between two polar plates, and the temperature drift is far lower than that of the piezoresistive type pressure sensor. Therefore, in some applications requiring severe temperature stability, such as altimeters, drones, etc., capacitive pressure sensors are usually used.

Typically, capacitive pressure sensors employ a stacked parallel plate capacitor parallel to the substrate, i.e., with both its upper and lower plate electrodes parallel to the substrate. The pressure sensor chip of this structure is large in size, and the area of the plate electrode needs to be reduced in order to reduce the chip size, which brings about a problem of sensitivity reduction. In order to reduce the sensitivity, it is generally necessary to reduce the thickness of the sensing upper plate, so that the process difficulty increases and the reliability is reduced.

Disclosure of Invention

The utility model provides a variable capacitance structure and a pressure sensor, wherein electrodes in the variable capacitance structure and the pressure sensor are parallel to the thickness direction of a substrate, so that when a chip with a smaller size is prepared, the thickness of a polar plate does not need to be reduced, the process difficulty of preparing the chip with the smaller size is reduced, and the reliability is improved, and the specific scheme is as follows:

in a first aspect, a variable capacitance structure is provided, which includes a substrate and at least one electrode pair arranged along a thickness direction of the substrate, each of the electrode pairs includes a first electrode and a second electrode, and a first groove is provided between the first electrode and the second electrode;

wherein at least one side of each electrode pair is provided with a second groove.

The gas-liquid separation device further comprises a medium layer, wherein the medium layer is positioned above the substrate, and at least one gas inlet hole is formed in the medium layer or the substrate and is used for being communicated with external gas.

Further, the first groove corresponding to each electrode pair is communicated with the corresponding air inlet hole.

Further, a plurality of electrode pairs are included, and a part of the first grooves corresponding to the electrode pairs are communicated with the corresponding air inlet holes, and the other part of the second grooves corresponding to the electrode pairs are communicated with the corresponding air inlet holes;

and an isolation column is arranged between the adjacent electrode pairs.

Further, a first isolation layer is arranged between each of the first electrode and the second electrode and the substrate.

Further, the diameter of the cross section of the air inlet hole is smaller than the diameter of the cross section of the first groove and the second groove.

In a second aspect, a pressure sensor is provided, where the pressure sensor includes the variable capacitance structure as described above, a first conductive structure and a second conductive structure electrically connected to each of the first electrodes and the second electrodes, respectively, are disposed in the dielectric layer, and a first pad and a second pad corresponding to each of the first conductive structures and each of the second conductive structures, respectively, are disposed on a side of the dielectric layer away from the substrate.

Further, a second isolation layer is arranged between each first conductive structure and each second conductive structure and the dielectric layer.

Furthermore, a signal processing circuit is arranged in the substrate, at least two third bonding pads which are respectively and independently electrically connected with the first bonding pad and the second bonding pad are arranged on the dielectric layer, and each third bonding pad is respectively and independently electrically connected with the signal processing circuit.

Further, at least one electrode pair constituting a fixed capacitance is included, the at least one electrode pair constituting a fixed capacitance being electrically connected to at least one electrode pair in the variable capacitance structure.

Further, the variable capacitance structure comprises a plurality of electrode pairs, and the pressure sensor comprises two capacitor sets connected in parallel, wherein the capacitor sets are formed by two electrode pairs connected in series in the variable capacitance structure, or the capacitor sets are formed by one electrode pair in the variable capacitance structure and one electrode pair forming a fixed capacitor connected in series, wherein the two capacitor sets connected in parallel form a wheatstone bridge structure.

In the utility model, on one hand, the first electrode and the second electrode in the electrode pair are arranged in parallel to the thickness direction of the substrate, namely the first electrode and the second electrode are arranged in a way of being vertical to the substrate of the substrate, when a chip with smaller size is prepared, the thickness of the electrode plate does not need to be reduced, the process difficulty of preparing the chip with smaller size is reduced, and the reliability is improved; on the other hand, a first groove for spacing the first electrode and the second electrode is arranged between the first electrode and the second electrode, so that the first electrode and the second electrode form a capacitor; the variable capacitance structure comprises a first electrode, a second electrode, a first groove and a second groove, wherein the first groove is arranged on at least one side of each electrode pair, when the first groove corresponding to the same electrode pair is communicated with outside air to receive air pressure, the change of the air pressure value can be detected or corresponding action can be executed, and the sensitivity is high. In another aspect, the pressure sensor of the present invention may include different capacitance groups, where the different capacitance groups have different detection ranges and detection sensitivities, so as to meet various detection requirements, and further, when the capacitance groups are electrode pairs with capacitance-increasing structures and electrode pairs with capacitance-decreasing structures, a differential capacitance is formed, so that when the pressure sensor detects pressure, the capacitance of one capacitance group increases, the capacitance of another capacitance group decreases, and the pressure sensor has higher detection accuracy and detection sensitivity.

Drawings

The technical solution and other advantages of the present invention will become apparent from the following detailed description of specific embodiments of the present invention, which is to be read in connection with the accompanying drawings.

FIG. 1 is a schematic diagram of a variable capacitor structure in which second grooves are distributed on both sides of an electrode of the variable capacitor, air inlets are communicated with the first grooves, and the air inlets are located in a dielectric layer;

FIG. 2 is a schematic diagram of a variable capacitor structure in which a second groove is formed on one side of a first electrode, an air inlet is communicated with the first groove, and the air inlet is located in a dielectric layer;

FIG. 3 is a schematic diagram of a variable capacitor structure in which second grooves are distributed on both sides of an electrode of the variable capacitor, air inlets are communicated with the first grooves, and the air inlets are located in a substrate;

FIG. 4 is a schematic diagram of a variable capacitance structure including an electrode pair with an increased capacitance structure and an electrode pair with a decreased capacitance structure according to the present invention;

FIG. 5 is a schematic diagram of a series connection of an electrode pair of an increased capacitance configuration and an electrode pair of a decreased capacitance configuration in accordance with the present invention;

FIG. 6 is a schematic diagram of a pressure sensor in one embodiment of the present invention;

FIG. 7 is a schematic diagram of a pressure sensor of the present invention comprising a fixed capacitance electrode pair and a variable capacitance electrode pair;

FIG. 8 is a schematic diagram of a Wheatstone bridge configuration formed by the capacitor bank C and the capacitor bank C connected in parallel according to an embodiment of the utility model;

FIG. 9 is a schematic diagram of a Wheatstone bridge structure formed by the capacitor bank D and the capacitor bank D connected in parallel according to an embodiment of the utility model.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the utility model, and not restrictive of the full scope of the utility model. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the term "and/or" herein is only one kind of association relationship describing the associated object, and means that there may be three kinds of relationships, for example, a and/or B, and may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" in this document generally indicates that the preceding and following related objects are in an "or" relationship unless otherwise specified.

The utility model discloses a variable capacitance structure, which comprises a substrate and at least one electrode pair arranged along the thickness direction of the substrate, wherein each electrode pair comprises a first electrode and a second electrode, and a first groove is formed between the first electrode and the second electrode;

In the present invention, the electrode pair in the variable capacitance structure is disposed along the thickness direction of the substrate, that is, perpendicular to the substrate of the substrate. The first electrode and the second electrode in each electrode are oppositely arranged and are separated by the first groove, so that a capacitor is formed. Further, at least one side of each electrode pair is provided with a second groove, for example, the second groove may be provided on one side of the electrode pair, or the second grooves may be provided on both sides of the motor pair, and the depths of the first groove and the second groove extend along the thickness direction of the substrate. For the same electrode pair, the first groove corresponding to the same electrode pair is communicated with the outside air to receive the air pressure, and the distance between the polar plates between the first electrode and the second electrode is changed, so that the size of the capacitor is changed.

In the utility model, on one hand, the first electrode and the second electrode in the electrode pair are arranged in parallel to the thickness direction of the substrate, namely the first electrode and the second electrode are arranged in a way of being vertical to the substrate of the substrate, when a chip with smaller size is prepared, the thickness of the electrode plate does not need to be reduced, the process difficulty of preparing the chip with smaller size is reduced, and the reliability is improved; on the other hand, a first groove for spacing the first electrode and the second electrode is arranged between the first electrode and the second electrode, so that the first electrode and the second electrode form a capacitor; the variable capacitance structure comprises a first electrode, a second electrode, a first groove and a second groove, wherein the first groove is arranged on at least one side of each electrode pair, when the first groove corresponding to the same electrode pair is communicated with outside air to receive air pressure, the change of the air pressure value can be detected or corresponding action can be executed, and the sensitivity is high.

As shown in fig. 1, in an embodiment of the variable capacitor structure of the present invention, the variable capacitor structure includes a substrate 1, a first electrode 2 and a second electrode 3 disposed along a thickness direction of the substrate 1, a first groove 4 is disposed between the first electrode 2 and the second electrode 3, and a second groove 5 is disposed on both one side of the first electrode 2 and one side of the second electrode 3, wherein the first groove 4 is in communication with an external gas, and when a gas pressure of the first groove 4 increases, a plate gap between the first electrode 2 and the second electrode 3 increases, so that a capacitance value of the variable capacitor structure decreases.

In one embodiment, the variable capacitor structure further comprises a dielectric layer located above the substrate, and at least one air inlet hole is arranged on the dielectric layer or the substrate and is used for communicating with outside air.

With continued reference to fig. 1, the variable capacitor structure further includes a dielectric layer 6, where the dielectric layer 6 covers the substrate 1 and is located at one side of the openings of the first recess 4 and the second recess 5, that is, the openings of the first recess 4 and the second recess 5 face the dielectric layer 6. In the present embodiment, the air inlet 7 is disposed on the medium layer or the substrate, specifically, when the air inlet 7 is disposed on the substrate 1, the air inlet 7 is disposed on the substrate 1 and is located at the other side of the openings of the first groove and the second groove, for example, as shown in fig. 1, the air inlet 7 is disposed on the medium layer, and the non-air inlet area of the medium layer covers the first groove 4 and the second groove 5.

In one embodiment, the first groove corresponding to each electrode pair is communicated with the corresponding air inlet hole.

As shown in fig. 1, the first groove 4 between the first electrode 2 and the second electrode 3 is communicated with the air inlet 7, and the air inlet 7 is located between the first electrode 2 and the second electrode 3.

In the case that the first grooves are communicated with the corresponding air inlet holes, the change of the plate distance can be divided into two possible embodiments, wherein one is that the first electrode 2 and the second electrode 3 are provided with the second grooves 5 on both sides, as shown in fig. 1, when the air pressure in the first groove 4 is increased, the first electrode 2 and the second electrode 3 are respectively deformed in the direction perpendicular to the thickness direction of the substrate 1 in the direction away from each other, thereby causing the distance between the first electrode 2 and the second electrode 3 to be increased and the capacitance to be reduced, and the other is that one side of the first electrode 2 or the second electrode 3 is provided with the second grooves 5, when the air pressure in the first groove 4 is increased, only one of the first electrode 2 and the third electrode 3 is deformed in the direction perpendicular to the thickness direction of the substrate 1, as shown in fig. 2, one side of the first electrode 2 is provided with the second grooves 5, when the air pressure of the second groove 5 increases, the first electrode 2 deforms in a direction away from the second electrode 3, and therefore, the capacitance of the variable capacitor in this case changes by half of that in the first case, and the two structures form a variable capacitor structure having different sensitivities.

Further, for the two embodiments, the distribution of the air inlets is divided into different manners, one manner is that the air inlets are located on the medium layer 6, exemplarily, as shown in fig. 1, the two sides of the first electrode 2 and the second electrode 3 are both provided with the second groove 5, the air inlets 7 are located on the medium layer 6 at positions corresponding to the first grooves 4, as shown in fig. 2, one side of the first electrode 2 is provided with the second groove 5, the air inlets 7 are located on the medium layer 6 at positions corresponding to the first grooves 4, and for the case that one side of the second electrode 3 is provided with the second groove 5, the air inlets 7 can be located on the medium layer 6 and correspond to the first grooves 4; alternatively, the air inlet holes 7 are located on the substrate 1, for example, as shown in fig. 3, the first electrode 2 and the second electrode 3 have second grooves 5 on both sides, and the air inlet holes 7 correspond to the first grooves 4 and are located on the substrate 1; similarly, the air intake hole 7 may be located on the substrate corresponding to the first groove 4 in the case where the first electrode 2 has the second groove 5 on one side, and the air intake hole 7 may be located on the substrate 1 corresponding to the first groove 4 in the case where the second electrode 3 has the second groove 5 on one side.

In the utility model, the variable capacitor structures with different sensitivities are obtained by communicating the first grooves with the corresponding air inlet holes and arranging different numbers of second grooves.

In one embodiment, the variable capacitance structure comprises a plurality of electrode pairs, and a part of the corresponding first grooves of the electrode pairs are communicated with the corresponding air inlet holes, and the other part of the corresponding second grooves of the electrode pairs are communicated with the corresponding air inlet holes;

and an isolation column is arranged between the adjacent electrode pairs.

In this embodiment, the variable capacitor structure may include a plurality of electrode pairs, as shown in fig. 4, the first groove 4 ' corresponding to the first electrode pair a on the left side communicates with the corresponding air inlet 7 ', and the second groove 5 "corresponding to the second electrode pair b on the right side is connected with the corresponding air inlet 7", when the gas in the variable capacitor structure enters the air inlets 7 ' and 7 "and causes the air pressure to increase, the plate distance between the first electrode 2 ' and the second electrode 3 ' in the left electrode pair increases, the capacitance decreases, the plate distance between the first electrode 2" and the second electrode 3 "in the right electrode pair decreases, and the capacitance increases, thereby forming a differential capacitor, which has higher sensitivity. Further, the isolation column 8 is arranged between different electrode pairs, so that the effect of blocking corresponding capacitors of the two electrode pairs is provided, and deformation caused by influence of air inlet pressure on each other is prevented.

Further, when the variable capacitance structure includes a plurality of electrode pairs, the first electrode pair and the second electrode pair may be connected in series or in parallel, for example, as shown in fig. 5, the first electrode pair a is connected in series with the second electrode pair b.

In one embodiment, each of the first electrode and the second electrode has a first isolation layer between the substrate.

In the present embodiment, the first electrode 2 and the second electrode 3 of each electrode pair may be formed by forming a groove on the substrate 1 during the preparation process, and then disposing a dielectric in the groove, in order to prevent migration of the first electrode 2 and the second electrode 3, as shown in fig. 1, a first isolation layer 9 is disposed between the substrate 1 and each of the first electrode 2 and the second electrode 3, and for example, the first isolation layer 9 may be an oxide layer.

In one embodiment, the diameter of the cross section of the air intake hole is smaller than the diameter of the cross section of the first groove and the second groove.

In the present embodiment, in order to prevent foreign substances from entering the first groove 4 and the second groove 5, the diameter of the cross section of the air intake hole 7 is smaller than the diameter of the cross section of the first groove 4 and the second groove 5.

The utility model also provides a pressure sensor which comprises the variable capacitance structure, wherein a first conductive structure and a second conductive structure which are respectively and electrically connected with each first electrode and each second electrode are arranged in the dielectric layer, and a first bonding pad and a second bonding pad which respectively correspond to each first conductive structure and each second conductive structure are arranged on one side of the dielectric layer away from the substrate.

Illustratively, as shown in fig. 6, the first conductive structure 10 is located above the first electrode 2, and the second conductive structure 11 is located above the second electrode 3. Further, the pressure sensor further includes a first pad 12 corresponding to the first conductive structure 10, and a second pad 13 corresponding to the second conductive structure 11, wherein the first pad 12 is located above the first conductive structure 10, and the second pad 13 is located above the second conductive structure 11.

In one embodiment, each of the first conductive structures and each of the second conductive structures has a second isolation layer between them and the dielectric layer.

In the present embodiment, the first conductive structures 10 and the second conductive structures 11 are formed by disposing a dielectric material in the through holes at corresponding positions in the dielectric layer, in order to avoid migration of the dielectric material, a second isolation layer 14 is disposed between each of the first conductive structures 10 and the second conductive structures 11 and the dielectric layer 6, and the second isolation layer 14 may be an oxide layer, for example.

In one embodiment, a signal processing circuit is disposed in the substrate, at least two third pads independently electrically connected to the first pad and the second pad are disposed on the dielectric layer, and each third pad is independently electrically connected to the signal processing circuit.

In this embodiment, as shown in fig. 6, in order to process the electric signal of the variable capacitance structure, a signal processing circuit 15 is provided in the substrate 1, at least two third pads 16 independently electrically connected to the first pad 12 and the second pad 13 are provided on the dielectric layer 6, so that the first electrode 2 is connected to the signal processing circuit 15 through the first conductive structure 10, the first pad 12, and the third pad 16 corresponding to the first electrode 2, and the second electrode 3 is connected to the signal processing circuit 15 through the second conductive structure 11, the second pad 13, and the third pad 16 corresponding to the second electrode 3, so that the signal processing circuit 15 can detect the current air pressure value or perform a corresponding operation by obtaining a change in capacitance value through a change in the plate pitch between the first electrode 2 and the second electrode 3.

In one embodiment, the pressure sensor further comprises at least one electrode pair constituting a fixed capacitance, the at least one electrode pair constituting the fixed capacitance being electrically connected to at least one electrode pair in the variable capacitance structure.

In the present embodiment, the pressure sensor is composed of a fixed capacitance electrode pair and a variable capacitance electrode pair, and as shown in fig. 7, a fixed electrode pair c is connected in series with a capacitance increasing type electrode pair b.

In one embodiment, the variable capacitance structure comprises a plurality of electrode pairs, the pressure sensor comprises two parallel-connected capacitance banks, the capacitance banks are formed by two series-connected electrode pairs in the variable capacitance structure, or the capacitance banks are formed by one electrode pair in the variable capacitance structure and one electrode pair forming a fixed capacitance in series, wherein the two parallel-connected capacitance banks form a wheatstone bridge configuration.

In this embodiment, the capacitor bank has a plurality of compositions, so the wheatstone bridge structure includes a plurality of types, and the capacitor bank may be a: the electrode pair of the capacitance increasing structure is connected in series with the electrode pair of the capacitance increasing structure, B: the electrode pair of the reduced capacitance structure is connected in series with the electrode pair of the reduced capacitance structure, C: the electrode pair of electric capacity increase formula structure and the electrode pair series connection of electric capacity reduction formula structure, D: the electrode pair of the fixed capacitor is connected in series with the electrode pair of the capacitance increasing structure, E: the fixed capacitor electrode pair is connected in series with the reduced capacitor electrode pair, thus, the Wheatstone bridge structure may be composed of capacitor bank A connected in parallel with capacitor bank A, capacitor bank B connected in parallel with capacitor bank B, capacitor bank C connected in parallel with capacitor bank C, capacitor bank D connected in parallel with capacitor bank D, capacitor bank E connected in parallel with capacitor bank E, capacitor bank A connected in parallel with capacitor bank B, capacitor bank A connected in parallel with capacitor bank C, capacitor bank A connected in parallel with capacitor bank D, capacitor bank A connected in parallel with capacitor bank E, capacitor bank B connected in parallel with capacitor bank C, capacitor bank B connected in parallel with capacitor bank D, capacitor bank B connected in parallel with capacitor bank E, capacitor bank C connected in parallel with capacitor bank D, capacitor bank D connected in parallel with capacitor bank E, for example, as shown in FIG. 8, B is the increased capacitor electrode pair, a is the reduced capacitor electrode pair, the structure of the Wheatstone bridge is that a capacitor bank C is connected with a capacitor bank C in parallel; as shown in fig. 9, b is an electrode pair having a capacitance increasing structure, c is an electrode pair having a fixed capacitance, and the wheatstone bridge structure is a case where the capacitor group D is connected in parallel with the capacitor group D. Therefore, the capacitor bank has various forms, has different detection ranges and detection sensitivities, and can meet different detection requirements.

Further, when one of the capacitor sets in the pressure sensor is the capacitor set C, the capacitor set C is a differential capacitor, and when the pressure sensor detects pressure, the capacitance detected by one electrode pair of the capacitor set C is increased, and the capacitance detected by the other electrode pair is decreased, so that the pressure sensor has higher detection accuracy and detection sensitivity.

In summary, although the present invention has been described with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, therefore, the scope of the present invention shall be determined by the appended claims.

Claims

1. A variable capacitance structure is characterized by comprising a substrate and at least one electrode pair arranged along the thickness direction of the substrate, wherein each electrode pair comprises a first electrode and a second electrode, and a first groove is arranged between the first electrode and the second electrode;

2. The variable capacitance structure of claim 1, comprising a dielectric layer, the dielectric layer being located over the substrate, the dielectric layer or the substrate having at least one gas inlet hole disposed therein for communicating with an external gas.

3. The variable capacitance structure of claim 2, wherein the corresponding first recess of each of the electrode pairs communicates with the corresponding inlet aperture.

4. The variable capacitance structure as claimed in claim 2, comprising a plurality of said electrode pairs, and wherein a portion of said first recesses corresponding to said electrode pairs communicate with corresponding said gas inlet holes, and another portion of said second recesses corresponding to said electrode pairs communicate with corresponding said gas inlet holes;

and an isolation column is arranged between the adjacent electrode pairs.

5. The variable capacitance structure of any one of claims 2 through 4, wherein each of the first and second electrodes has a first isolation layer between the substrate.

6. The variable capacitance structure of any one of claims 2 through 4, wherein the diameter of the cross section of the air intake hole is smaller than the diameter of the cross section of the first groove and the second groove.

7. A pressure sensor comprising a variable capacitance structure according to any one of claims 2-6, wherein a first and a second conductive structure are provided within the dielectric layer in electrical connection with each of the first and second electrodes, respectively, and wherein a side of the dielectric layer remote from the substrate is provided with a first and a second pad corresponding to each of the first and second conductive structures, respectively.

8. The pressure sensor of claim 7, wherein each of the first conductive structures and each of the second conductive structures has a second isolation layer between them and the dielectric layer.

9. The pressure sensor of claim 8, wherein a signal processing circuit is disposed within the substrate, and wherein at least two third pads are disposed on the dielectric layer and are independently electrically connected to the first pad and the second pad, respectively, each of the third pads being independently electrically connected to the signal processing circuit.

10. The pressure sensor of claim 9, comprising at least one electrode pair forming a fixed capacitance electrically connected to at least one electrode pair in the variable capacitance structure.

11. The pressure sensor of claim 9, wherein the variable capacitance structure comprises a plurality of electrode pairs, and the pressure sensor comprises two parallel-connected capacitor banks, the capacitor banks being formed by two series-connected electrode pairs in the variable capacitance structure, or the capacitor banks being formed by one electrode pair in the variable capacitance structure and one electrode pair forming a fixed capacitor in series, wherein the two parallel-connected capacitor banks form a wheatstone bridge configuration.