Pressure detection device and pressure detection method

Abstract

The application discloses a pressure detection device and method, and belongs to the technical field of pressure sensors.The device comprises a capacitive pressure sensor and a control module; the sensor is composed of an ion conductive film, a working electrode, a counter electrode and a reference electrode.The working electrode is in contact with the first surface of the film with microstructure to form a first capacitor which changes with external pressure and noise; the counter electrode is closely attached to the second surface of the film to form a second capacitor which changes only with noise.The control module applies an anti-phase excitation signal to the working electrode and the counter electrode, collects voltage signals under two excitation states through the reference electrode, eliminates common-mode noise through differential processing, extracts voltage signals which only reflect external pressure, and then accurately calculates the pressure value.The application effectively suppresses the interference of temperature, humidity and material characteristic drift, and significantly improves the accuracy, stability and reliability of pressure measurement.

Description

Technical Field

[0001] This invention belongs to the field of pressure sensor technology, specifically relating to a pressure detection device and a pressure detection method. Background Technology

[0002] Capacitive pressure sensors are widely used in many fields such as human-computer interaction, medical health, and robotic tactile sensing due to their advantages such as simple structure, high sensitivity, and low power consumption.

[0003] In recent years, capacitive sensors based on ion-conducting voltage-sensitive materials (such as ion gels and ion elastomers) have attracted widespread attention due to their excellent flexibility and high sensitivity. The core principle of these sensors relies on the double-layer capacitance formed at the interface between the electrode and the ion-conducting material. When pressure is applied to the sensor, the contact area between the ion-conducting voltage-sensitive material and the electrode changes, resulting in a change in the double-layer capacitance, thereby achieving pressure sensing.

[0004] However, existing ion-capacitive pressure sensors still have areas for improvement:

[0005] First, the capacitance of double-layer capacitors is highly susceptible to factors such as ambient temperature, humidity, and the solvation and aging of the ionic liquid itself. Temperature changes significantly alter the dielectric constant and viscosity of the ionic liquid, causing capacitance drift; changes in ambient humidity may cause the ionic liquid to absorb or lose moisture, similarly interfering with capacitor stability. This inherent environmental sensitivity leads to severe drift in the sensor output signal, significantly reducing measurement accuracy and reliability.

[0006] Secondly, common device structures (such as sandwich structures or interdigitated electrode structures) have inherent defects. In sandwich structures, both the upper and lower interfaces typically require simultaneous deformation to generate an effective capacitance change, resulting in a high trigger threshold. Interdigitated electrode structures often require two adjacent electrodes to simultaneously change their contact area with the ionogel, limiting their response sensitivity and trigger speed, making it difficult to detect minute or rapid pressure changes.

[0007] Third, to address the temperature drift problem, existing technologies have proposed several solutions. Chinese patent CN119595150B proposes a scheme using an independent reference capacitor for temperature compensation. However, this method requires the reference capacitor and the sensing capacitor to be in completely identical temperature environments. In practical applications, even a small temperature difference can lead to a sharp decrease in compensation accuracy. Furthermore, the nonlinear changes in the properties of ionic liquids (such as non-first-order relationships caused by solvation effects) complicate the compensation model, requiring complex calculations such as square root operations, increasing the difficulty of signal processing and limiting the compensation effect.

[0008] Therefore, there is an urgent need in the field for a pressure detection scheme that can suppress interference from environmental factors, while possessing high sensitivity, fast response, and high reliability, in order to overcome the aforementioned deficiencies of the prior art.

[0009] It should be noted that this part of the present invention only provides background technology related to the present invention, and does not necessarily constitute prior art or known technology. Summary of the Invention

[0010] This invention provides a pressure detection device and a pressure detection method, which at least solves the problems of existing pressure sensors being susceptible to interference from environmental and internal factors, and having insufficient sensitivity and reliability.

[0011] To achieve the above objectives, in a first aspect, the present invention provides a pressure detection device, comprising a capacitive pressure sensor and a control module; the capacitive pressure sensor includes an ion-conductive thin film, a working electrode, a counter electrode, and a reference electrode; the working electrode contacts a first surface of the ion-conductive thin film to form a first capacitor; the counter electrode contacts a second surface of the ion-conductive thin film to form a second capacitor; the reference electrode is disposed on the ion-conductive thin film; wherein the first surface has a microstructure, and the working electrode contacts the microstructure so that the capacitance value of the first capacitor is configured to vary with external pressure and noise signals; the counter electrode is tightly attached to the second surface so that the capacitance value of the second capacitor is configured to vary only with noise signals; the control module is electrically connected to the working electrode, the counter electrode, and the reference electrode; the control module is configured to: apply a first excitation signal and a second excitation signal having a preset phase difference to the working electrode and the counter electrode; acquire a first voltage signal corresponding to the first excitation state and a second voltage signal corresponding to the second excitation state from the reference electrode; perform differential processing on the first voltage signal and the second voltage signal to obtain a voltage signal that varies only with external pressure; and determine the external pressure value based on the voltage signal that varies only with external pressure.

[0012] Preferably, the reference electrode is disposed on one side of the first surface or on one side of the second surface.

[0013] Preferably, the reference electrode and the counter electrode have the same or different dimensions and geometry.

[0014] Preferably, the first excitation signal and the second excitation signal are positive and negative symmetrical voltage waveforms with equal amplitude and the same excitation time.

[0015] Preferably, the first excitation state is a steady-state period in which the first excitation signal is at a high level and the second excitation signal is at a low level, and the second excitation state is a steady-state period in which the first excitation signal is at a low level and the second excitation signal is at a high level; the values ​​of the first voltage signal and the second voltage signal are determined by the voltage division ratio between the capacitance values ​​of the first capacitor and the second capacitor.

[0016] Preferably, the differential processing includes calculating the difference between the first voltage signal and the second voltage signal.

[0017] Preferably, the differential processing further includes calculating the sum of the first voltage signal and the second voltage signal, and the sum is used to monitor the state of the capacitive pressure sensor.

[0018] Secondly, the present invention also provides a pressure detection method applied to the above-mentioned pressure detection device, the method comprising:

[0019] A first excitation signal and a second excitation signal with a preset phase difference are applied to the working electrode and the counter electrode;

[0020] A first voltage signal corresponding to the first excitation state and a second voltage signal corresponding to the second excitation state are respectively acquired from the reference electrode;

[0021] Differential processing is performed on the first voltage signal and the second voltage signal to obtain a voltage signal that changes only with external pressure;

[0022] The external pressure value is determined based on a voltage signal that changes only with external pressure.

[0023] Preferably, the first excitation signal and the second excitation signal are positive and negative symmetrical voltage waveforms with equal amplitude and the same excitation time.

[0024] Preferably, the first excitation state is a steady-state period in which the first excitation signal is at a high level and the second excitation signal is at a low level, and the second excitation state is a steady-state period in which the first excitation signal is at a low level and the second excitation signal is at a high level.

[0025] The values ​​of the first voltage signal and the second voltage signal are determined by the voltage division ratio between the capacitance values ​​of the first capacitor and the second capacitor.

[0026] Preferably, the differential processing includes calculating the difference between the first voltage signal and the second voltage signal.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. This invention innovatively designs an integrated three-electrode structure comprising a working electrode, a counter electrode, and a reference electrode. The working electrode contacts the first surface of a microstructured ion-conducting thin film to form a first capacitance that varies with external pressure and noise signals. The counter electrode is tightly bonded to the second surface of the ion-conducting thin film to form a second capacitance that varies only with noise signals. By utilizing the reference electrode to acquire the voltage divider signal under both positive and negative excitation, and suppressing common-mode noise through a differential algorithm, a pure pressure signal is accurately separated, significantly improving the sensor's resistance to interference from temperature fluctuations, humidity changes, and ion characteristic drift.

[0029] 2. This invention constructs a microstructure interface only on the first surface of the ion-conductive thin film, ensuring tight adhesion between the electrode and the second surface. Therefore, only a small deformation under external pressure is required to cause a significant change in the interface capacitance, achieving a low trigger threshold and fast dynamic response. This solves the problems of low sensitivity and slow response of traditional interdigitated electrodes or sandwich structures, making it particularly suitable for high-frequency, low-pressure detection scenarios. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of a capacitive pressure sensor provided in an embodiment of the present invention;

[0032] Figure 2 An equivalent circuit diagram of a capacitive pressure sensor provided in an embodiment of the present invention;

[0033] Figure 3 The equivalent simplified circuit diagram of the capacitive pressure sensor provided in the embodiment of the present invention when it reaches a steady state after charging, and the reference electrode is an ideal voltmeter;

[0034] Figure 4 The sampling waveform diagram of the pressure detection device provided in the embodiment of the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] 100. Capacitive pressure sensor; 110. Ion-conductive thin film; 120. Working electrode; 130. Counter electrode; 140. Reference electrode. Detailed Implementation

[0037] In this invention, unless otherwise stated, directional terms such as "up," "down," "left," and "right" are generally understood in conjunction with the accompanying drawings and the directions shown in actual applications.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0039] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0040] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. The terms "optional" and "discretionary" mean that they may or may not be included (or may or may not be present).

[0041] like Figure 1 As shown, the present invention provides a pressure detection device, including a capacitive pressure sensor 100 and a control module; the capacitive pressure sensor 100 includes an ion-conductive thin film 110, a working electrode 120, a counter electrode 130, and a reference electrode 140; the working electrode 120 contacts a first surface of the ion-conductive thin film 110 to form a first capacitor; the counter electrode 130 contacts a second surface of the ion-conductive thin film 110 to form a second capacitor; the reference electrode 140 is disposed on the ion-conductive thin film 110; wherein, the first surface has a microstructure, and the working electrode 120 contacts the microstructure, so that the capacitance value of the first capacitor is configured to change with external pressure and noise signals. The counter electrode 130 is tightly attached to the second surface so that the capacitance of the second capacitor is configured to vary only with the noise signal; the control module is electrically connected to the working electrode 120, the counter electrode 130, and the reference electrode 140; the control module is configured to: apply a first excitation signal and a second excitation signal with a preset phase difference to the working electrode 120 and the counter electrode 130; acquire a first voltage signal corresponding to the first excitation state and a second voltage signal corresponding to the second excitation state from the reference electrode 140; perform differential processing on the first voltage signal and the second voltage signal to obtain a voltage signal that varies only with the external pressure; and determine the external pressure value based on the voltage signal.

[0042] This invention innovatively designs an integrated three-electrode structure comprising a working electrode, a counter electrode, and a reference electrode. The working electrode contacts the first surface of a microstructured ion-conducting thin film to form a first capacitance that varies with external pressure and noise signals. The counter electrode is tightly bonded to the second surface of the ion-conducting thin film to form a second capacitance that varies only with noise signals. By utilizing the reference electrode to acquire voltage divider signals under both positive and negative excitation, and suppressing common-mode noise through a differential algorithm, a pure pressure signal is accurately separated, significantly improving the sensor's resistance to interference from temperature fluctuations, humidity changes, and ion characteristic drift.

[0043] It should be noted that the noise signals include: 1. Temperature fluctuation noise (caused by changes in ambient temperature leading to changes in the dielectric constant, viscosity, and ion mobility of the ionic liquid, resulting in capacitance drift); 2. Humidity change noise (caused by changes in ambient humidity leading to hygroscopic changes in capacitance due to hygroscopic impurities or hygroscopic absorption or loss of water by the ionic liquid); 3. Solvation effect noise (caused by residual high-boiling-point solvents, treatment agents, or moisture affecting the properties of the ionic liquid, resulting in nonlinear capacitance drift).

[0044] like Figure 2 As shown, in the capacitive pressure sensor, the working electrode contacts the first surface of the ion-conducting thin film and forms a first composite impedance structure in the initial state, specifically including:

[0045] The first thermal modulation capacitor C11 is formed by an electric double layer at the interface between the working electrode and the ion-conducting thin film, and its capacitance value changes with temperature.

[0046] The first force modulation capacitor C12 is caused by the change in the contact area between the microstructure of the first surface and the working electrode, and its capacitance value changes with the external pressure.

[0047] The first force modulation resistor R11 characterizes the contact resistance between the microstructure and the electrode, which changes with pressure.

[0048] The first ion gel internal resistance R12 represents the bulk resistance of the ion-conducting thin film, which is affected by temperature and material properties.

[0049] The electrode is tightly bonded to the second surface of the ion-conducting thin film to form a second composite impedance structure, including:

[0050] The second thermal modulation capacitor C21 is formed by an electric double layer at the interface between the counter electrode and the ion-conducting thin film, and its capacitance value changes only with temperature.

[0051] The second ion gel internal resistance R21 is the bulk resistance of the ion-conducting thin film under the electrode path, which is affected by temperature and material properties.

[0052] A third composite impedance structure is formed between the reference electrode and the ion-conducting thin film, including:

[0053] The third thermal modulation capacitor C31 is the double-layer capacitance at the interface between the reference electrode and the ion-conducting thin film.

[0054] The third ion gel internal resistance R31 is the bulk resistance of the ion-conducting thin film under the reference electrode path, which is affected by temperature and material properties.

[0055] like Figure 3 As shown, when the circuit reaches a steady state of charging, the equivalent circuit between the working electrode and the counter electrode can be simplified to a series structure of the first capacitor C1 and the second capacitor C2. The reference electrode is used to measure the voltage at the voltage divider point of this series structure. This voltage value is related to the capacitance ratio of C1 and C2, thereby reflecting the change in external pressure and suppressing the influence of common-mode noise.

[0056] Specifically, because the measurement involves both sides of the same thin film, external forces exert a proportional influence on the film material. When the film is charged via the working and counter electrodes, the voltage division ratio is determined by the capacitance ratio of C1 and C2, and is unrelated to the absolute values ​​of the two capacitors. If the amount of charge absorbed by the reference electrode during voltage measurement is sufficiently small, the effect on the voltage division ratio of the two capacitors during the measurement process can be ignored. Therefore, the voltage measured by the reference electrode can reflect changes in external pressure, while simultaneously eliminating the influence of noise signals such as temperature, humidity, and solvation on the sensor.

[0057] Preferably, the ion-conducting film is formed by crosslinking a uniformly dispersed ionic liquid in polyvinylidene fluoride (PVDF). Specifically, in one embodiment, the ion-conducting film can be formed by curing an ion gel solution. The ion gel solution can be obtained by uniformly mixing a PVDF-based polymer, an ionic liquid, a wetting agent, a solvent, and a filler. The PVDF-based polymer can include a first PVDF-based polymer and a second PVDF-based polymer; for example, the first PVDF-based polymer includes PVDF, and the second PVDF-based polymer includes PVDF-HFP. The anions of the ionic liquid include at least one selected from hexafluorophosphate anion, tetrafluoroborate anion, bis(trifluoromethanesulfonyl)imide anion, trifluoromethanesulfonate anion, acetate anion, dicyandiamide anion, bromide anion, ethyl sulfate anion, and hydrothioate anion. The cations of the ionic liquid include at least one selected from 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, and 1-octyl-3-methylimidazolium cation. The wetting agent includes dimethyl carbonate; the solvent includes at least one of acetone, N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran. The filler includes at least one of nano-iron oxide, nano-ferric oxide, nano-alumina, nano-calcium carbonate, nano-zinc oxide, nano-tin oxide, nano-cerium oxide, and fumed silica.

[0058] In this embodiment, the first PVDF-based polymer has high crystallinity and high content, enabling it to spontaneously form microstructures (spherical or near-spherical structures). The second PVDF-based polymer has low crystallinity and low content, and during film formation, it participates less in the formation of the polymer skeleton of spherical or near-spherical structures, acting as a bonder for the spherical or near-spherical structures formed by the first PVDF-based polymer, thus forming a stable polymer ionogel particle layer. Adding fillers to the ionogel solution promotes the spontaneous formation of the polymer ionogel particle layer, improves the consistency of the uneven structure on one side of the ion-conductive film, and avoids inconsistencies in strength, resilience, and sensitivity at different points on the gel film. As an example, the specific preparation method of the ionogel solution can be found in previous patents CN119060476B and CN119060387B. However, it should be noted that the ionogel solution in this application can also be prepared using other components, and this application does not impose any restrictions on this.

[0059] Furthermore, the first surface has microstructures, which can be in the form of nanopores, microchannels, microprotrusions, etc. These microstructures can increase the surface area of ​​the ion exchange membrane, improve ion conduction efficiency, and help improve the capacitance effect. The shape of the microstructure can be referred to in the descriptions in patents CN119060476B and CN119060387B, and will not be repeated here.

[0060] Preferably, the working electrode is in contact with the microstructure so that the capacitance of the first capacitor is configured to vary with external pressure and noise signals. Specifically, the microstructure significantly increases the initial contact area between the electrode and the ion-conducting thin film, placing it in a state highly susceptible to mechanical modulation. When external pressure is applied, the microstructure undergoes elastic deformation, causing a significant change in the actual contact area between the electrode and the film. According to the double-layer capacitance formula (C∝A / d), this change in contact area directly translates into a change in capacitance, thus sensitively responding to pressure signals. Simultaneously, the physicochemical basis constituting this double-layer capacitor, including the dielectric properties of the ionic liquid, ion mobility, and interface characteristics, is also affected by noise signals such as temperature, humidity, and material aging. These noise signals cause capacitance drift in a common-mode manner. Therefore, the capacitance change of the first capacitor formed by the microstructure interface is essentially a superposition of the response to external pressure changes and the response to noise signals.

[0061] Preferably, the counter electrode is tightly bonded to the second surface so that the capacitance of the second capacitor is configured to vary only with noise signals. The tight bonding and fixation of the counter electrode to the second surface of the ion-conductive thin film ensures that the contact area between them remains constant. This means that the capacitance of the second capacitor formed by this interface is no longer modulated by external mechanical pressure. However, the physicochemical properties of the ionic liquid material constituting the capacitor (such as dielectric constant and conductivity) will still respond to changes in noise signals such as temperature and humidity. These noise signals cause drift in the double-layer capacitance value. Therefore, the capacitance of the second capacitor is configured to vary only with these common-mode noise signals, thus becoming a pure reference signal source.

[0062] Understandably, the second surface can be smooth or have microstructures. The key is to use a suitable bonding method to form a stable and reliable contact interface with the counter electrode, thereby ensuring that the contact area remains constant under external pressure, so that the second capacitor is only sensitive to noise signals.

[0063] Specifically, to ensure the contact area between the thin film and the electrode remains stable and does not change with pressure, an adhesive with ionic conductivity is needed to tightly bond and fix the electrode to the ionicly conductive thin film. Considering process convenience, a coatable ion-gel hot melt adhesive solution is chosen. This hot melt adhesive is a solution with a solid content of approximately 20%, which can be applied to the electrode at room temperature, forming a solid hot melt adhesive film after the solvent evaporates. The hot melt adhesive film becomes a viscous gel above its softening temperature (approximately 60°C), possessing the ability to bond films. The appropriate ion-gel hot melt adhesive content needs to be matched according to the ionic liquid content within the film being bonded.

[0064] It should be noted that any adhesive that can bond an ion exchange membrane to the electrode surface and has the corresponding ion conductivity can be used in this invention; there are no particular limitations to this invention.

[0065] Preferably, the reference electrode is disposed on one side of the first surface or one side of the second surface. More preferably, the reference electrode is disposed on one side of the second surface. The function of the reference electrode is to provide a stable potential reference point for the sensor system, used to measure the capacitive voltage difference between the working electrode and the counter electrode. Its working principle is that any electronically conductive electrode that can form a stable contact with the ion gel film can establish a stable electric double layer structure, thus serving as a reference electrode. From a circuit principle perspective, the reference electrode only needs to be drawn from a point between the first capacitor and the second capacitor formed by the working electrode and the counter electrode to measure the voltage difference; its theoretical spatial arrangement is not particularly restricted.

[0066] Furthermore, in the actual design and manufacturing of this invention, it is preferable to separately arrange the reference electrode and the counter electrode on one side of the iontophoresis adhesive film layer (i.e., the second surface side). Both the reference electrode and the counter electrode need to establish stable and reliable electrical contact with the iontophoresis film. Arranging them together on the same surface of the sensor greatly facilitates the synchronous fixing and bonding of the two electrodes during manufacturing through a single synchronous process step (e.g., by coating or hot-pressing the same layer of iontophoresis adhesive). This layout simplifies the assembly process, improves production efficiency and consistency, and avoids the complex alignment and multiple bonding operations caused by dispersing the electrodes in different positions.

[0067] It should be noted that the names of the working electrode, counter electrode, and reference electrode are defined according to their functions, while in terms of physical form, interdigitated electrodes or flat plates are both applicable.

[0068] Specifically, the working electrode is disposed on one side of the first surface of the ion-conducting thin film. In a preferred embodiment, the working electrode may be an interdigitated electrode connected in parallel and short-circuited. This structural design helps to provide space for the microstructural deformation of the ion-conducting thin film under high pressure, and avoids the adsorption effect between the thin film and the smooth planar electrode due to the complete expulsion of air, thereby effectively preventing the increase of sensor hysteresis.

[0069] The counter electrode and the reference electrode are preferably disposed together on one side of the second surface of the ion-conducting thin film. The key to the counter electrode is that it must form a stable and reliable contact interface with the second surface of the film to ensure that the contact area does not change with pressure. For this purpose, both interdigitated electrodes and planar electrodes can meet the requirements. Considering that the reference electrode is usually also arranged on the second surface, using interdigitated electrodes provides spatial layout convenience and facilitates electrode integration.

[0070] The reference electrode is used to measure the potential of an ion-conducting thin film under an excited state. Its setting requirement is to maintain good contact with the film. Therefore, there are no special requirements for its shape. Thus, the reference electrode can be the same as or different from the counter electrode in terms of size and geometry. This application does not limit this.

[0071] Preferably, the control module is configured to: apply a first excitation signal and a second excitation signal with a preset phase difference to the working electrode and the counter electrode; acquire a first voltage signal corresponding to the first excitation state and a second voltage signal corresponding to the second excitation state from the reference electrode; perform differential processing on the first voltage signal and the second voltage signal to obtain a voltage signal that varies only with the external pressure; and determine the external pressure value based on the voltage signal that varies only with the external pressure.

[0072] The specific principle of the control module is as follows: When the first excitation state is applied, the first voltage signal V1 measured by the reference electrode is the superposition of the pressure signal, noise signal, and the inherent bias of the circuit. When the second excitation state with the opposite phase is applied, the polarity of the original pressure signal is reversed, while the polarity of the common-mode noise signal and the circuit bias remains unchanged. At this time, the measured second voltage signal V2 is the superposition of the reversed pressure signal, noise signal, and bias. Subsequently, V1 and V2 are differentially processed (V1-V2), so that the noise and bias with unchanged polarity are completely canceled out, while the pressure signal with reversed polarity is multiplied, thereby extracting a pure voltage signal that is only related to the external pressure and suppresses the interference of noise signals. This setting achieves efficient suppression of common-mode noise from the level of signal detection principle, significantly improving the accuracy, stability, and reliability of the sensor, and making its output results almost unaffected by problems that have long plagued traditional sensors, such as ionic liquid characteristic drift, temperature fluctuations, and humidity changes.

[0073] The control module preferably uses positive and negative symmetrical voltage waveforms with equal amplitude and the same excitation time as the first and second excitation signals, such as square waves, sine waves, etc. Square waves are preferred, as they are easier to generate and calculate using a microcontroller. This symmetrical and periodic excitation method can match the subsequent differential processing algorithm, providing conditions for achieving efficient common-mode noise suppression. Specifically, equal amplitudes ensure symmetrical electric field strength applied to the working electrode and the counter electrode, making the capacitive noise response related to the excitation signal amplitude caused by environmental factors (temperature, humidity) and the inherent DC bias error of the circuit completely consistent in both excitation states. The same excitation time ensures that the charging and discharging process of the capacitor reaches a completely steady state in both states, thereby eliminating transient errors introduced by different charging degrees. This setting allows all common-mode noise and DC bias components with the same amplitude and unchanged polarity to be completely canceled when differential calculation is performed on the voltage signals measured in the two steady states. The effective pressure signal, which is only sensitive to external pressure and whose response signal has opposite polarity in the two excitation states, is significantly multiplied, thereby greatly improving the signal-to-noise ratio and measurement sensitivity of the output signal, while simplifying the signal processing flow and reducing the requirements for hardware circuit accuracy.

[0074] Preferably, such as Figure 4As shown, the control module preferably defines the first excitation state as a steady-state period where the first excitation signal (working electrode) is at a high level and the second excitation signal (counter electrode) is at a low level, and the second excitation state as a steady-state period where the two levels are opposite. This setting can utilize the principle of a capacitive voltage divider to convert the modulation effect of external pressure on the capacitance ratio into a potential change on the reference electrode that can be accurately measured. Specifically, after the circuit between the working electrode and the counter electrode reaches a steady state, ion migration stops, and the voltage value measured on the reference electrode is determined by the capacitance ratio of the first capacitor (C1, sensitive to pressure and noise signals) and the second capacitor (C2, sensitive only to noise signals), and is independent of the absolute value of the capacitance, the internal resistance of the ion gel, etc. When external pressure is applied, only the capacitance of C1 changes, thereby changing this voltage division ratio, resulting in a change in the reference electrode potential; by applying two excitation states with opposite phases, the pressure-induced change in C1 will cause the two measured voltage signals to produce changes in magnitude and opposite directions, while the simultaneous proportional influence of the noise signal on C1 and C2 will manifest as a common mode with the same magnitude and direction in both measurements. When the two voltage signals are subsequently processed differentially, the common-mode noise is completely canceled out, while the effective signal caused solely by pressure is multiplied. This suppresses the drift introduced by factors such as changes in ambient temperature and humidity and material aging, and significantly improves the signal-to-noise ratio, accuracy, and long-term stability of the pressure measurement signal.

[0075] Preferably, the differential processing includes calculating the difference between the first voltage signal and the second voltage signal. This operation mathematically separates the effective signal generated solely by external pressure and eliminates common-mode environmental noise. When two completely opposite phase excitation states are applied, the noise signal and the inherent DC bias of the circuit appear as common-mode signals with identical amplitude and polarity in both measurements. However, the pressure signal generated by the change in the capacitance of the first capacitor due to the change in external pressure appears as an effective differential signal with equal amplitude but opposite polarity in both measurements. Therefore, subtracting these two voltage signals completely cancels out the common-mode noise component, while multiplying the pressure signal component. This setup removes all environmental interference and circuit errors from the final output, extracting a pure and amplified voltage signal that is only proportional to the external pressure. This significantly improves the sensor's signal-to-noise ratio, measurement accuracy, and long-term stability. Furthermore, this method eliminates the need for complex calibration models or algorithms, simplifying the signal processing and reducing dependence on the accuracy of external components.

[0076] Preferably, the differential processing further includes calculating the sum of the first voltage signal and the second voltage signal, which is used to monitor the state of the capacitive pressure sensor. The purpose is to provide the system with a built-in diagnostic tool, allowing for effective assessment of the sensor's overall health and operating environment through real-time monitoring of this sum. Specifically, since this sum (V1+V2) mathematically superimposes all common-mode components from both measurements (including capacitance baseline drift caused by changes in ambient temperature and humidity, aging of the ion gel material, and the DC bias voltage of the circuit itself), while simultaneously canceling out the differential signal generated by changes in external pressure, the stability of this sum directly reflects the sum and changing trend of all common-mode noise sources. Ideally, a properly functioning sensor should maintain a relatively stable sum. If an abnormal drift or abrupt change in the sum is detected, it indicates that the sensor may have encountered extreme environmental stress (such as temperatures far exceeding the range), irreversible degradation of the ion gel material, or a circuit system malfunction (such as amplifier offset voltage drift). This allows for timely triggering of an early warning signal, indicating the need for calibration or maintenance, thus enhancing the reliability and maintainability of the entire pressure detection device.

[0077] Preferably, the process by which the control module determines the external pressure value based on the voltage signal is a calibration and conversion process that maps the measured pure differential voltage signal to a precise pressure value. This process first relies on a pressure-voltage calibration curve established in advance through calibration experiments. Under known and controllable conditions, a series of precise standard pressure values ​​(such as using weights or a standard pressure source) are applied to the sensor, and the corresponding voltage values ​​output by the control module after differential processing are recorded simultaneously. Then, a functional mapping relationship between the voltage signal and the external pressure value is established through mathematical fitting (such as linear, polynomial, or piecewise fitting). In actual measurement, after the control module acquires and processes the voltage signal that changes only with the external pressure in real time, it calculates the final digital pressure value by looking up a table or directly substituting it into the calibration function.

[0078] More specifically, the core model of this invention simplifies the path between the working electrode and the counter electrode into a capacitor voltage divider consisting of a first capacitor C1 and a second capacitor C2. The reference electrode measures the voltage at the midpoint of this voltage divider. The following is the derivation of the calculation formula.

[0079] 1. Formula for a capacitor voltage divider (steady state)

[0080] The derivation of the capacitor voltage divider formula is based on the principles of charge conservation and voltage distribution when capacitors are connected in series. The first capacitor C1 and the second capacitor C2 are connected in series, and the input voltage... When applied across the series combination, the output voltage If the voltage is taken from both ends of the second capacitor C2 (i.e., the first capacitor C1 is connected between the input and output, while the second capacitor C2 is connected between the output and ground), then the voltage at the dividing point of the capacitor divider is determined by the ratio of the capacitance values ​​of the two capacitors. The specific calculation formula is as follows:

[0081]

[0082] in:

[0083] This is the total excitation voltage difference applied between the working electrode and the counter electrode;

[0084] This is the capacitance value of the first capacitor C1;

[0085] This is the capacitance value of the second capacitor C2;

[0086] This is the voltage at the voltage divider point measured by the reference electrode.

[0087] 2. Voltage expressions under two excitation states

[0088] The control module applies two excitation states with a phase difference:

[0089] In the first excitation state:

[0090] Voltage applied to the working electrode (C1 terminal) ;

[0091] Apply a voltage of 0 to the electrode (C2 terminal);

[0092] Total excitation voltage difference ;

[0093] The first voltage signal measured for:

[0094]

[0095] In the second excitation state:

[0096] A voltage of 0 is applied to the working electrode (C1 terminal);

[0097] Apply voltage to electrode (C2 terminal) ;

[0098] Total excitation voltage difference ;

[0099] The measured second voltage signal for:

[0100]

[0101] 3. Differential processing

[0102] Calculate the difference between the two measurements:

[0103]

[0104] 4. Noise signal suppression

[0105] Noise signals will affect both capacitor C1 and capacitor C2 simultaneously. Assume that due to environmental changes, the capacitance values ​​of both capacitors have a scaling factor of [value missing]. Synchronous changes ( (Noise factor)

[0106]

[0107]

[0108] Substitute the changed capacitance into the difference calculation formula:

[0109]

[0110] It can be seen that the differential output signal With noise factor Irrelevant.

[0111] 5. Response to pressure signals

[0112] External pressure This will only change the capacitance of the first capacitor C1, without affecting the second capacitor C2. Let the capacitance of the first capacitor C1 be [value missing] when there is no pressure. Apply pressure Afterwards, the capacitance changes to When the first capacitor C1 responds to external pressure, its capacitance value... The calculation is as follows:

[0113]

[0114] The differential output at this point is:

[0115]

[0116] Final output voltage Only the capacitance change caused by pressure Related.

[0117] The above formula derivation proves from a circuit principle perspective that the differential processing of this invention can eliminate the influence of common-mode noise such as environmental temperature and humidity fluctuations and material aging. By measuring the voltage of the reference electrode under two inverse excitation states and performing differential calculations, the final output voltage signal... Only the change in the first capacitance C1 caused by external pressure Related to, but not to, the absolute value of the capacitance and the common-mode noise factor. Irrelevant.

[0118] The present invention also provides a pressure detection method applied to the above-mentioned pressure detection device, the method comprising:

[0119] S102, Apply a first excitation signal and a second excitation signal with a preset phase difference to the working electrode and the counter electrode;

[0120] In one embodiment, the first excitation signal and the second excitation signal are square wave voltage signals with equal amplitude and the same excitation time.

[0121] S104. Acquire a first voltage signal corresponding to the first excitation state and a second voltage signal corresponding to the second excitation state from the reference electrode;

[0122] In one embodiment, the first excitation state is a steady-state period in which the first excitation signal is at a high level and the second excitation signal is at a low level, and the second excitation state is a steady-state period in which the first excitation signal is at a low level and the second excitation signal is at a high level; the values ​​of the first voltage signal and the second voltage signal are determined by the voltage division ratio between the capacitance values ​​of the first capacitor and the second capacitor.

[0123] S106. Perform differential processing on the first voltage signal and the second voltage signal to obtain a voltage signal that changes only with external pressure;

[0124] In one embodiment, differential processing includes calculating the difference between a first voltage signal and a second voltage signal.

[0125] S108. Determine the external pressure value based on the voltage signal that changes only with the external pressure.

[0126] The pressure detection method of the present invention applies reverse excitation signals to the working electrode and the counter electrode, and uses a reference electrode to collect voltage signals under the two excitation states. Then, differential processing is performed on the two voltage signals to effectively eliminate the interference of common-mode noise such as temperature, humidity and material property drift, thereby accurately extracting the pure voltage signal that is only related to the external pressure, and finally achieving pressure measurement with high accuracy, high stability and high reliability.

[0127] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A pressure detection device, characterized in that, include: A capacitive pressure sensor, comprising an ion-conducting thin film, a working electrode, a counter electrode, and a reference electrode; The working electrode contacts the first surface of the ion-conducting thin film and forms a first capacitor; the counter electrode contacts the second surface of the ion-conducting thin film and forms a second capacitor; the reference electrode is disposed on the ion-conducting thin film. The first surface has a microstructure, and the working electrode is in contact with the microstructure so that the capacitance of the first capacitor is configured to change with external pressure and noise signals; the counter electrode is in close contact with the second surface so that the capacitance of the second capacitor is configured to change only with noise signals. The control module is electrically connected to the working electrode, the counter electrode, and the reference electrode; The control module is configured to: apply a first excitation signal and a second excitation signal with a preset phase difference to the working electrode and the counter electrode; acquire a first voltage signal corresponding to the first excitation state and a second voltage signal corresponding to the second excitation state from the reference electrode; perform differential processing on the first voltage signal and the second voltage signal to obtain a voltage signal that varies only with external pressure; and determine the external pressure value based on the voltage signal that varies only with external pressure.

2. The pressure detection device according to claim 1, characterized in that, The reference electrode is disposed on one side of the first surface or on one side of the second surface.

3. The pressure detection device according to claim 1, characterized in that, The reference electrode may have the same or different dimensions and geometry as the counter electrode.

4. The pressure detection device according to claim 1, characterized in that, The first excitation signal and the second excitation signal are positive and negative symmetrical voltage waveforms with equal amplitude and the same excitation time.

5. The pressure detection device according to claim 4, characterized in that, The first excitation state is a steady state in which the first excitation signal is at a high level and the second excitation signal is at a low level, and the second excitation state is a steady state in which the first excitation signal is at a low level and the second excitation signal is at a high level. The values ​​of the first voltage signal and the second voltage signal are determined by the voltage division ratio between the capacitance values ​​of the first capacitor and the second capacitor.

6. The pressure detection device according to claim 1, characterized in that, The differential processing includes calculating the difference between the first voltage signal and the second voltage signal.

7. The pressure detection device according to claim 1, characterized in that, The differential processing further includes calculating the sum of the first voltage signal and the second voltage signal, the sum being used to monitor the state of the capacitive pressure sensor.

8. A pressure detection method, applied to the pressure detection device as described in any one of claims 1 to 7, characterized in that, The method includes: A first excitation signal and a second excitation signal having a preset phase difference are applied to the working electrode and the counter electrode; A first voltage signal corresponding to the first excitation state and a second voltage signal corresponding to the second excitation state are respectively acquired from the reference electrode; Differential processing is performed on the first voltage signal and the second voltage signal to obtain the voltage signal that changes only with external pressure; The external pressure value is determined based on a voltage signal that changes only with external pressure.

9. The pressure detection method according to claim 8, characterized in that, The first excitation signal and the second excitation signal are positive and negative symmetrical voltage waveforms with equal amplitude and the same excitation time.

10. The pressure detection method according to claim 9, characterized in that, The first excitation state is a steady state in which the first excitation signal is at a high level and the second excitation signal is at a low level, and the second excitation state is a steady state in which the first excitation signal is at a low level and the second excitation signal is at a high level. The values ​​of the first voltage signal and the second voltage signal are determined by the voltage division ratio between the capacitance values ​​of the first capacitor and the second capacitor.

11. The pressure detection method according to claim 8, characterized in that, The differential processing includes calculating the difference between the first voltage signal and the second voltage signal.

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