A single-cell based dual-mode sensor and a method of measuring thereof

Abstract

This invention relates to the field of sensor measurement technology and discloses a dual-modal sensor based on a single unit and its measurement method. The sensor includes: a flexible upper substrate for providing flexible support and encapsulation protection for the entire sensor surface; an upper electrode layer containing a first circular electrode for generating capacitance changes in response to pressure stimulation and serving as the output terminal for electrical signals; an intermediate sensitive layer; a lower electrode layer; and a flexible lower substrate. The method includes: system initialization, synchronous acquisition and transmission of dual-modal signals, signal processing, and signal output and display. This invention, through the combination of concentric circular electrode design and independent signal channels, achieves hardware decoupling of temperature and pressure signals, solving the problems of temperature drift interference in pressure measurement and reliance on algorithm compensation caused by traditional sensors sharing the same electrode and signal channel, fundamentally improving the accuracy and reliability of dual-modal measurement.

Description

Technical Field

[0001] This invention relates to the field of sensor measurement technology, specifically to a dual-modal sensor based on a single unit and its measurement method. Background Technology

[0002] With the widespread application of intelligent sensing systems in fields such as industrial automation, medical diagnosis, environmental monitoring and human-computer interaction, higher requirements are placed on the ability of sensors to acquire multi-parameter and multi-modal signals simultaneously. Traditional sensors usually only sense a single physical quantity, such as temperature, pressure, strain or light intensity. Their functions are limited and their integration is low, making it difficult to meet the information fusion needs of modern complex systems.

[0003] A search revealed Chinese patent CN113720386B, which discloses a dual-modal flexible sensor for measuring temperature and strain. The sensor includes two flexible substrates on the outermost sides, with strain-sensitive materials attached to their outer surfaces and electrodes covering their inner surfaces. A dielectric material layer is sandwiched between the electrodes. The flexible substrates are flexible thin films and are non-conductive. This dual-modal flexible sensor utilizes the change in resistance of the strain-sensitive material with strain and the changes in the dielectric constant and thickness of the dielectric material with temperature to achieve dual-modal measurement of temperature and strain.

[0004] A search revealed Chinese patent CN114894244B, which discloses a flexible stress-temperature dual-mode sensor, its fabrication method, and its application. The flexible stress-temperature dual-mode sensor is a multi-level Young's modulus structure, including a high Young's modulus segment and low Young's modulus segments disposed at both ends of the high Young's modulus segment. The low Young's modulus segment includes a first hollow elastic tube doped with magnetic particles, and the high Young's modulus segment includes a second hollow elastic tube without magnetic particles, a reinforcing tube, an amorphous wire, and an inductor coil. The reinforcing tube is disposed within the second hollow elastic tube, and the amorphous wire is disposed within the reinforcing tube. This invention's flexible stress-temperature dual-mode sensor enables the detection and differentiation of strain and temperature using a single sensing unit. Its method of use is simple and efficient, and it has high detection accuracy.

[0005] In the above-mentioned technical solutions, the same pair of electrodes simultaneously extracts temperature and pressure responses. The piezoresistive material is subjected to both stress and temperature modulation, resulting in the two physical quantities sharing the same signal channel. Temperature drift is directly superimposed on the pressure output, requiring subsequent algorithm compensation. The hardware does not achieve essential decoupling, leading to poor performance. In addition, the capacitance change rate of traditional circular flat electrode under pressure is only related to the electrode spacing, while temperature detection requires maximizing the contact perimeter between the sensitive material and the electrode to reduce resistance noise. Using a single disk cannot simultaneously satisfy the high capacitance sensitivity of the pressure channel and the low noise of the temperature channel, resulting in a decrease in temperature resolution when the pressure sensitivity is increased. Based on this, the present invention designs a dual-modal sensor based on a single unit and its measurement method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a dual-modal sensor based on a single unit and its measurement method, which solves the problems of relying on post-processing algorithm compensation and failing to achieve essential decoupling in the prior art.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] A dual-modal sensor based on a single unit, comprising:

[0009] The flexible upper substrate is used to provide flexible support and encapsulation protection for the entire sensor's upper surface.

[0010] The upper electrode layer includes a first circular electrode for generating capacitance changes in response to pressure stimulation and serving as an output terminal for electrical signals.

[0011] The intermediate sensitive layer, composed of a composite material that responds simultaneously to temperature and pressure stimuli, is used to sense changes in external temperature and pressure and convert them into resistance and capacitance signals, respectively.

[0012] The lower electrode layer includes a second circular electrode and a ring electrode concentric with the second circular electrode, which is used to perform hardware decoupling of temperature and pressure signals in conjunction with the middle sensitive layer.

[0013] The flexible undersubstrate is used to provide flexible support for the lower surface of the entire sensor, encapsulate and protect it, and allow it to adhere to the object under test.

[0014] The first circular electrode of the upper electrode layer, the intermediate sensitive layer, and the second circular electrode of the lower electrode layer together constitute a pressure-sensitive capacitor system, which is used to respond to pressure stimulation through capacitance changes; the second circular electrode and the annular electrode of the lower electrode layer together with the intermediate sensitive layer constitute a temperature-sensitive resistor system, which is used to respond to temperature stimulation through resistance changes; the pressure-sensitive capacitor system and the temperature-sensitive resistor system share the intermediate sensitive layer and have independent signal channels.

[0015] Preferably, the outer surface of the flexible substrate is provided with a micro-nano-level wrinkled structure to maintain the conductivity continuity of the electrodes when subjected to tensile, bending and torsional deformation.

[0016] Preferably, the diameter of the first circular electrode of the upper electrode layer is smaller than the inner diameter of the annular electrode of the lower electrode layer and smaller than the diameter of the second circular electrode, in order to ensure that the deformation under pressure only effectively changes the electrode spacing of the pressure-sensitive capacitor system, while giving the temperature-sensitive resistor system the maximum electrode contact perimeter.

[0017] Preferably, the intermediate sensitive layer includes a gradient foam installed at the bottom of the upper electrode layer, ZnO nanorods are installed at the bottom of the gradient foam and distributed in multiple matrix arrays, an ion gel is installed at the bottom of the ZnO nanorods, and magnetic amorphous wires are installed at the bottom of the ion gel.

[0018] Preferably, the pore size of the gradient foam is distributed in a continuous gradient along the thickness direction, with an average pore size of 50-100 μm on the side near the upper electrode layer and an average pore size of 10-30 μm on the side near the ion gel, which is used to generate a controllable change in the electrode spacing under pressure loading, while suppressing lateral crosstalk.

[0019] The ZnO nanorods have a center-to-center distance of 200-400 nm, and the surface of the rod array is treated with oxygen plasma to introduce hydroxyl functional groups, which are used to improve the interfacial bonding strength with the ion gel and reduce the contact resistance.

[0020] Preferably, the ionogel is composed of a crosslinked network of 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imine salt (EMIM-TFSI) and poly(2-hydroxyethyl acrylate) (PHEA) to maintain resistance and temperature response in the range of -40°C to 120°C.

[0021] The surface of the magnetic amorphous wire is covered with a silicon dioxide insulating layer, and the wire axis is oriented by a magnetic field so that the direction of the wire axis is perpendicular to the radial direction of the annular electrode, which is used to suppress magnetostriction interference when the temperature changes.

[0022] Preferably, a telescopic rod is installed between the intermediate sensitive layer and the lower electrode layer. A damping spring is installed on the outer ring of the telescopic rod. The top of the telescopic rod is fixedly connected to the intermediate sensitive layer and the bottom of the telescopic rod is fixedly connected to both sides of the second circular electrode. This is used to guide the intermediate sensitive layer to undergo controllable deformation in the vertical direction under pressure load and to provide buffering through the damping spring.

[0023] Preferably, the electrode materials of the upper electrode layer and the lower electrode layer are both Au and Cr double-layer thin films, and a moisture-proof insulating layer is vapor-deposited on the surface to prevent electrode oxidation and moisture corrosion.

[0024] Both the flexible upper substrate and the flexible lower substrate are polyimide films with a silicone rubber buffer layer spin-coated on their surfaces to enhance the flexibility of the device.

[0025] A thermal actuator is installed in the cavity of the flexible lower substrate. The thermal actuator is electrically coupled to the lower electrode layer and is used to provide local temperature excitation during temperature measurement.

[0026] Preferably, the initial capacitance of the pressure-sensitive capacitor system is determined by the area and initial spacing of the first circular electrode and the second circular electrode; the temperature-sensitive resistor system forms a ring-shaped resistance path between the second circular electrode and the ring electrode, and its resistance changes accordingly with temperature.

[0027] As another aspect of the present invention, a measurement method based on a dual-modal sensor of a single unit is provided, the method comprising the following steps:

[0028] Step S1: System initialization. In the initial state without external pressure and temperature stimulation, the reference capacitance value of the pressure-sensitive capacitor system composed of the first circular electrode and the second circular electrode, and the reference resistance value of the temperature-sensitive resistor system composed of the second circular electrode and the ring electrode through the intermediate sensitive layer are detected and recorded respectively, so as to provide a calculation reference for subsequent temperature and pressure change measurement.

[0029] Step S2: Simultaneous acquisition and transmission of dual-modal signals. When the sensor senses external stimuli, it simultaneously acquires the output of two independent signal channels.

[0030] The pressure-sensitive capacitor system generates a capacitance change signal because the intermediate sensitive layer deforms and the distance between the plates changes due to pressure.

[0031] The temperature-sensitive resistor system generates a resistance change signal because the ionic conductivity of the ion gel or the resistivity of the magnetic amorphous wire in the intermediate sensitive layer changes due to temperature changes. The capacitance change signal and the resistance change signal are respectively transmitted to an external signal processing unit.

[0032] Step S3, signal processing: based on the capacitance change signal and the pre-stored capacitance-pressure calibration curve, calculate and output the current absolute pressure value. This process utilizes the gradient pore size distribution characteristics of the gradient foam to achieve a linear response.

[0033] Based on the resistance change signal and the pre-stored resistance and temperature calibration curves, the current absolute temperature value is calculated and output. This process is dominated by the thermosensitive properties of the ion gel.

[0034] The concentric structure of the second circular electrode and the annular electrode in the lower electrode layer provides a physical basis for decoupling the two signals.

[0035] Step S4, Signal Output and Display: The calculated absolute pressure and absolute temperature values ​​are output as independent data streams to the display unit or host computer system to complete the synchronous, dual-modal measurement of external temperature and pressure stimuli.

[0036] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0037] 1. This invention, through the combination of concentric electrode design and independent signal channels, achieves hardware decoupling of temperature and pressure signals, solving the problems of temperature drift interference in pressure measurement and reliance on algorithm compensation caused by traditional sensors sharing the same electrode and signal channel, fundamentally improving the accuracy and reliability of dual-modal measurement.

[0038] 2. This invention, through the size matching of the small-diameter circular electrode in the upper electrode layer and the large-diameter circular electrode and ring electrode in the lower electrode layer, ensures that the electrode spacing of the pressure-sensitive capacitor system changes efficiently when under pressure to improve sensitivity, and also enables the temperature-sensitive resistor system to obtain the maximum electrode contact perimeter to reduce resistance noise. This solves the contradiction that a single electrode structure cannot simultaneously satisfy high capacitance sensitivity and low resistance noise.

[0039] 3. This invention, through the combination of gradient pore size distribution of gradient foam and spring buffer structure, achieves controllable and linear deformation of the intermediate sensitive layer under pressure loading, suppresses lateral crosstalk and plastic deformation, and improves the linearity, repeatability and lifespan of pressure measurement; by combining the wide temperature range stability of ion gel with the magnetic field orientation and insulating coating of magnetic amorphous wire, the interference of magnetostriction on the resistance signal during temperature changes is suppressed, thereby improving the accuracy and anti-interference ability of temperature measurement. Attached Figure Description

[0040] Figure 1 This is a front-view stereoscopic structural diagram of the present invention;

[0041] Figure 2 This is a schematic diagram of the test structure of the present invention;

[0042] Figure 3 This is a schematic diagram of the structure of the flexible upper substrate of the present invention;

[0043] Figure 4 This is a schematic diagram of the upper electrode layer and the intermediate sensitive layer structure of the present invention;

[0044] Figure 5 This is a schematic diagram of the structure of the intermediate sensitive layer of the present invention;

[0045] Figure 6This is a schematic diagram of the structure of the lower electrode layer of the present invention;

[0046] Figure 7 This is a side view of the lower electrode layer of the present invention;

[0047] Figure 8 This is a flowchart illustrating the measurement method of the present invention.

[0048] Among them: 1. Flexible upper substrate; 2. Upper electrode layer; 3. Middle sensitive layer; 4. Lower electrode layer; 5. Flexible lower substrate; 101. Micro-nano scale wrinkled structure; 201. First circular electrode; 301. Gradient foam; 302. ZnO nanorod; 303. Ion gel; 304. Magnetic amorphous wire; 305. Telescopic rod; 306. Damping spring; 401. Second circular electrode; 402. Ring electrode; 501. Thermal actuator. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Example 1; please refer to Figures 1-8 A dual-modal sensor based on a single unit, comprising:

[0051] Flexible upper substrate 1 is used to provide flexible support and encapsulation protection for the upper surface of the entire sensor;

[0052] The upper electrode layer 2 includes a first circular electrode 201, which is used to form a capacitance change in response to pressure stimulation and to serve as the output terminal of an electrical signal.

[0053] The intermediate sensitive layer 3 is made of a composite material that responds to both temperature and pressure stimuli. It is used to sense changes in external temperature and pressure and convert them into resistance and capacitance signals, respectively.

[0054] The lower electrode layer 4 includes a second circular electrode 401 and an annular electrode 402 concentric with the second circular electrode 401, which is used to cooperate with the intermediate sensitive layer 3 to perform hardware decoupling of temperature and pressure signals.

[0055] The flexible substrate 5 is used to provide flexible support for the lower surface of the entire sensor, encapsulate and protect it, and allow it to adhere to the object under test.

[0056] The first circular electrode 201 of the upper electrode layer 2, the intermediate sensitive layer 3, and the second circular electrode 401 of the lower electrode layer 4 together constitute a pressure-sensitive capacitor system, which is used to respond to pressure stimulation through capacitance changes; the second circular electrode 401 and the ring electrode 402 of the lower electrode layer 4 together with the intermediate sensitive layer 3 constitute a temperature-sensitive resistor system, which is used to respond to temperature stimulation through resistance changes; the pressure-sensitive capacitor system and the temperature-sensitive resistor system share the intermediate sensitive layer 3 and have independent signal channels.

[0057] The outer surface of the flexible substrate 1 is provided with a micro-nano-scale wrinkled structure 101 to maintain the conductivity continuity of the electrode when subjected to tensile, bending and torsional deformation.

[0058] The diameter of the first circular electrode 201 of the upper electrode layer 2 is smaller than the inner diameter of the annular electrode 402 of the lower electrode layer 4, and smaller than the diameter of the second circular electrode 401. This is to ensure that the deformation under pressure only effectively changes the electrode spacing of the pressure-sensitive capacitor system, while giving the temperature-sensitive resistor system the maximum electrode contact perimeter.

[0059] The intermediate sensitive layer 3 includes a gradient foam 301 installed at the bottom of the upper electrode layer 2. ZnO nanorods 302 are installed at the bottom of the gradient foam 301 and are distributed in multiple matrix arrays. Ion gel 303 is installed at the bottom of the ZnO nanorods 302 and magnetic amorphous wires 304 are installed at the bottom of the ion gel 303.

[0060] The pore size of the gradient foam 301 is continuously gradient distributed along the thickness direction. The average pore size on the side near the upper electrode layer 2 is 50-100μm and the average pore size on the side near the ion gel 303 is 10-30μm. This is used to generate controllable changes in the electrode spacing under pressure loading, while suppressing lateral crosstalk.

[0061] The center-to-center distance between adjacent ZnO nanorods 302 is 200-400 nm, and the surface of the rod array is treated with oxygen plasma to introduce hydroxyl functional groups, which are used to improve the interfacial bonding strength with ion gel 303 and reduce the contact resistance.

[0062] Ion gel 303 is composed of a crosslinked network of 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonylimide) salt EMIM-TFSI and poly(2-hydroxyethyl acrylate) PHEA, and is used to maintain resistance and temperature response in the range of -40°C to 120°C.

[0063] The surface of the magnetic amorphous wire 304 is covered with a silicon dioxide insulating layer, and the wire axis is oriented by a magnetic field so that the direction of the wire axis is perpendicular to the radial direction of the annular electrode 402, in order to suppress magnetostriction interference when the temperature changes.

[0064] A telescopic rod 305 is installed between the intermediate sensitive layer 3 and the lower electrode layer 4. A damping spring 306 is installed on the outer ring of the telescopic rod 305. The top of the telescopic rod 305 is fixedly connected to the intermediate sensitive layer 3 and the bottom of the telescopic rod 305 is fixedly connected to both sides of the second circular electrode 401. This is used to guide the intermediate sensitive layer 3 to undergo controllable deformation in the vertical direction under pressure load and to provide buffering through the damping spring 306.

[0065] The electrode materials of the upper electrode layer 2 and the lower electrode layer 4 are both Au and Cr double-layer thin films, and a moisture-proof insulating layer is vapor-deposited on the surface to prevent electrode oxidation and moisture corrosion.

[0066] Both the flexible upper substrate 1 and the flexible lower substrate 5 are polyimide films with a silicone rubber buffer layer spin-coated on their surfaces to enhance the flexibility of the device.

[0067] A thermal actuator 501 is installed in the cavity of the flexible lower substrate 5. The thermal actuator 501 is electrically coupled to the lower electrode layer 4 and is used to provide local temperature excitation during temperature measurement.

[0068] The initial capacitance of the pressure-sensitive capacitor system is determined by the area and initial spacing of the first circular electrode 201 and the second circular electrode 401; the temperature-sensitive resistor system forms a ring resistance path between the second circular electrode 401 and the ring electrode 402, and its resistance changes accordingly with temperature.

[0069] The working principle of this embodiment of the invention is as follows: The pressure-sensitive capacitor system consists of a first circular electrode 201 in the upper electrode layer 2, a middle sensitive layer 3, and a second circular electrode 401 in the lower electrode layer 4. Its initial capacitance C0 can be expressed as:

[0070] ;

[0071] Where: ε₀ is the vacuum permittivity; ε r d0 is the equivalent relative permittivity of the intermediate sensitive layer 3; A is the effective overlap area of ​​the first circular electrode 201 and the second circular electrode 401; d0 is the initial electrode spacing.

[0072] When an external pressure P is applied, the gradient foam 301 in the intermediate sensitive layer 3 undergoes compression deformation, causing the electrode spacing to decrease to d(P). At this time, the capacitance becomes:

[0073] ;

[0074] Because the gradient foam 301 has a pore size gradient structure, with a pore size of 50–100 μm on the side near the upper electrode layer 2 and 10–30 μm on the side near the ion gel 303, it exhibits an approximately linear compression characteristic under pressure, thus making ΔC and P linearly related, which facilitates subsequent calibration and decoupling.

[0075] The temperature-sensitive resistor system consists of a second circular electrode 401 and a ring electrode 402 in the lower electrode layer 4, which form a ring resistance path through the intermediate sensitive layer 3. The resistance R(T) of this path is mainly determined by the ionic conductivity of the ion gel 303 and the resistivity of the magnetic amorphous wire 304.

[0076] The ionogel 303 is composed of an EMIM-TFSI and PHEA cross-linked network, exhibiting high ion mobility and temperature-sensitive response characteristics in the temperature range of -40℃ to 120℃, which dominates the trend of resistance change with temperature. The magnetic amorphous wire 304 is oriented by a magnetic field, i.e., the wire axis is perpendicular to the radial direction of the annular electrode 402, to suppress magnetostriction interference caused by temperature changes and ensure the temperature uniformity of resistance change.

[0077] By sharing the intermediate sensitive layer 3 but independently arranging the electrode structure, the signal decoupling at the physical level is achieved between the pressure-sensitive capacitor system and the temperature-sensitive resistor system: the capacitor system only responds to the change in the thickness of the layer (pressure); the resistor system only responds to the change in the conductivity of the layer (temperature); the lower electrode layer 4 adopts a concentric circle structure, namely the second circular electrode 401 and the ring electrode 402, which effectively isolates the electric field and current path of the two systems and avoids cross interference.

[0078] Example 2; please refer to Figures 1-8 In this embodiment of the invention, a measurement method based on a dual-modal sensor with a single unit is provided, the method comprising the following steps:

[0079] Step S1: System initialization. In the initial state without external pressure and temperature stimulation, the reference capacitance value of the pressure-sensitive capacitor system composed of the first circular electrode 201 and the second circular electrode 401, and the reference resistance value of the temperature-sensitive resistor system composed of the second circular electrode 401 and the ring electrode 402 through the intermediate sensitive layer 3 are detected and recorded respectively, so as to provide a calculation reference for subsequent temperature and pressure change measurement.

[0080] Step S2: Simultaneous acquisition and transmission of dual-modal signals. When the sensor senses external stimuli, it simultaneously acquires the output of two independent signal channels.

[0081] The pressure-sensitive capacitor system generates a capacitance change signal because the middle sensitive layer 3 is deformed and the distance between the plates changes due to pressure.

[0082] The temperature-sensitive resistor system generates a resistance change signal because the ionic conductivity of the ion gel 303 or the resistivity of the magnetic amorphous wire 304 in the intermediate sensitive layer 3 changes due to temperature changes. The capacitance change signal and the resistance change signal are respectively transmitted to the external signal processing unit.

[0083] Step S3, signal processing: based on the capacitance change signal and the pre-stored capacitance-pressure calibration curve, calculate and output the current absolute pressure value. This process utilizes the gradient pore size distribution characteristics of gradient foam 301 to achieve a linear response.

[0084] Based on the resistance change signal and the pre-stored resistance and temperature calibration curve, the current absolute temperature value is calculated and output. This process is dominated by the temperature-sensitive properties of ion gel 303.

[0085] The concentric structure of the second circular electrode 401 and the annular electrode 402 in the lower electrode layer 4 provides a physical basis for decoupling the two signals.

[0086] Step S4, Signal Output and Display: The calculated absolute pressure and absolute temperature values ​​are output as independent data streams to the display unit or host computer system to complete the synchronous, dual-modal measurement of external temperature and pressure stimuli.

[0087] The working principle of this invention embodiment is as follows: Step S1, system initialization: Under conditions without external stimuli, the reference capacitance value C of the pressure-sensitive capacitor system is measured and recorded respectively. ref The reference resistance value R of the temperature-sensitive resistor system ref These two benchmark values ​​serve as zero-point references for subsequent solutions, used to eliminate system drift and initial errors.

[0088] Step S2: Simultaneous acquisition of dual-modal signals. When the sensor is stimulated by the outside world, the intermediate sensitive layer 3 is compressed and deformed under pressure, resulting in a change in capacitance ΔC. At the same time, the temperature change causes a change in the conductivity of the ion gel 303, resulting in a change in resistance ΔR. The two signals are acquired synchronously through independent signal channels to avoid time delay and sampling error.

[0089] Step S3, signal processing and model solving: the pressure calculation model is based on a pre-calibrated capacitance-pressure curve.

[0090] ;

[0091] Using the measured capacitance value C meas Inversion stress value:

[0092] ;

[0093] Where k C The capacitance-pressure sensitivity coefficient is determined by the mechanical properties of gradient foam 301.

[0094] The temperature calculation model is based on a pre-calibrated resistance-temperature profile:

[0095] ;

[0096] Using the measured resistance value R meas Inversion temperature value:

[0097] ;

[0098] Where k R The resistance-temperature sensitivity coefficient is mainly determined by the temperature-sensitive properties of ion gel 303.

[0099] Step S4: Independent output and display. Finally, the calculated pressure value P and temperature value T are output as independent data streams via serial port and I / O port. 2 The C or wireless module outputs to the host computer or display terminal to complete the dual-modal synchronous measurement.

[0100] Example 3; please refer to Figures 1-8 This embodiment provides a complete parameterized example of integrating the single-unit dual-modal sensor into a flexible wristband for synchronous monitoring of human wrist temperature and pulse pressure, and describes the entire process from initialization to data output.

[0101] Initialization was completed under no-load, 25°C constant temperature chamber. The reference capacitor C for the pressure-sensitive capacitor system was used. ref =12.6pF (@100kHz LCR meter); Temperature-sensitive resistor system reference resistor R ref =18.3kΩ (@1V DC excitation).

[0102] Pressure calibration: 0–150 kPa in 10 kPa increments, record ΔC = C(P) - C ref The sensitivity k was obtained. C =0.114pFkPa -1 linearity R ² >0.998;

[0103] Temperature calibration: 20–42℃ in 1℃ increments (covering the human skin area), record ΔR = R(T) – R ref The sensitivity k was obtained. R =–0.75kΩ℃ -1 (Negative temperature coefficient), linearity R 2 >0.995;

[0104] Cross-coupling tests showed that the resistance change introduced by the 150 kPa full-scale pressure was <0.3%, and the capacitance drift caused by the 42℃ extreme temperature was <0.2%, verifying the effectiveness of physical decoupling.

[0105] Step S1: Power on the system, apply a 20mW pulse for 2 seconds to the thermal actuator 501 to raise the local temperature by 0.5℃, and verify R. ref Drift <0.1%, calibration confirmed.

[0106] Step S2: After the wristband is worn, the first circular electrode 201 is in close contact with the skin. The pulse beat causes the gradient foam 301 to compress periodically, and the capacitance change ΔC≈0.09pF (corresponding to a pulse pressure of 0.8kPa). The pulse waveform is obtained by synchronously collecting data for 10 seconds.

[0107] Step S3: R was measured at a skin temperature of 33.5℃. meas =15.7kΩ, substitute into the formula;

[0108] T=25℃+(R ref –R meas ) / 0.75kΩ℃ -1 =33.5℃;

[0109] Step S4: The microcontroller (nRF52832) sets P = ΔC / 0.114pFkPa. -1 Packed with T at 100ms intervals, uploaded to the mobile APP via BLE, the pulse rate is displayed in real time as 72 beats / min and the temperature as 33.5℃. The error is ≤0.2℃ compared with a medical infrared thermometer and ≤5% compared with a cuff blood pressure monitor.

[0110] After continuous wear for 8 hours, the capacitance baseline drift was 0.05pF (equivalent to 0.4kPa), and the resistance baseline drift was 80Ω (equivalent to 0.1℃), meeting the requirements for long-term monitoring; after bending 5000 times (bending radius 10mm), the electrode resistance change was <2%, and the micro-nano-level wrinkled structure 101 maintained the conductivity integrity; the gradient foam 301 had a resilience rate of >95% and no plastic deformation, ensuring the sensor lifespan of >10000 pressure cycles.

[0111] Working principle: The flexible upper substrate 1 and flexible lower substrate 5 enclose the sensor in a "sandwich" structure. The first circular electrode 201 of the upper electrode layer 2, the intermediate sensitive layer 3, and the second circular electrode 401 of the lower electrode layer 4 form a "capacitor sheet". When the gradient foam 301 is flattened, the distance between the two electrodes becomes closer, the capacitance immediately increases, and the pressure is read. The second circular electrode 401 and the annular electrode 402 of the lower electrode layer 4 sandwich the intermediate sensitive layer 3 in the middle, forming a "resistance ring". As the temperature rises, the ions in the ion gel 303 move faster, and the magnetic amorphous wire 304 also changes resistance with temperature. The resistance value of the entire resistance ring changes accordingly, and the temperature is read. The two sets of electrodes share the same layer of sensitive material, but run two independent circuits, without interfering with each other, achieving natural decoupling at the hardware level.

[0112] After the sensor is attached to the object being measured, the capacitance channel tracks the minute thickness changes caused by each pulse compression in real time, while the resistance channel simultaneously tracks changes in skin temperature; the two signals are sampled synchronously and transmitted in a time-division manner. The microcontroller directly converts the capacitance change into a pressure value by referring to a pre-stored calibration curve, and directly converts the resistance change into a temperature value by referring to another temperature curve. Finally, the two results are packaged and sent out, completing a dual-modal synchronous measurement.

[0113] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A dual-modal sensor based on a single unit, characterized in that, include: A flexible upper substrate (1) is used to provide flexible support and encapsulation protection for the upper surface of the entire sensor; The upper electrode layer (2) includes a first circular electrode (201) for forming capacitance changes in response to pressure stimulation and serving as an output terminal for electrical signals; The intermediate sensitive layer (3) is composed of a composite material that responds to both temperature and pressure stimuli. It is used to sense changes in external temperature and pressure and convert them into resistance and capacitance signals, respectively. The lower electrode layer (4) includes a second circular electrode (401) and a ring electrode (402) concentric with the second circular electrode (401), which is used to cooperate with the intermediate sensitive layer (3) to perform hardware decoupling of temperature and pressure signals; The flexible substrate (5) is used to provide flexible support, encapsulation protection and adhesion to the object under test for the entire sensor. The first circular electrode (201) of the upper electrode layer (2), the intermediate sensitive layer (3), and the second circular electrode (401) of the lower electrode layer (4) together constitute a pressure-sensitive capacitor system, which is used to respond to pressure stimulation through capacitance changes; the second circular electrode (401) and the ring electrode (402) of the lower electrode layer (4) together with the intermediate sensitive layer (3) constitute a temperature-sensitive resistor system, which is used to respond to temperature stimulation through resistance changes; the pressure-sensitive capacitor system and the temperature-sensitive resistor system share the intermediate sensitive layer (3) and have independent signal channels; The diameter of the first circular electrode (201) of the upper electrode layer (2) is smaller than the inner diameter of the annular electrode (402) of the lower electrode layer (4) and smaller than the diameter of the second circular electrode (401), in order to ensure that the deformation under pressure only effectively changes the electrode spacing of the pressure-sensitive capacitor system, while making the temperature-sensitive resistor system have the largest electrode contact perimeter. The intermediate sensitive layer (3) includes a gradient foam (301) installed at the bottom of the upper electrode layer (2). ZnO nanorods (302) are installed at the bottom of the gradient foam (301) and are distributed in multiple matrix arrays. Ionic gel (303) is installed at the bottom of the ZnO nanorods (302), and magnetic amorphous wires (304) are installed at the bottom of the ionic gel (303).

2. The dual-modal sensor based on a single unit according to claim 1, characterized in that: The outer surface of the flexible upper substrate (1) is provided with a micro-nano-level wrinkled structure (101) to maintain the conductivity continuity of the electrode when subjected to tensile, bending and torsional deformation.

3. A dual-modal sensor based on a single unit according to claim 1, characterized in that: The pore size of the gradient foam (301) is distributed in a continuous gradient along the thickness direction. The average pore size on the side near the upper electrode layer (2) is 50-100 μm and the average pore size on the side near the ion gel (303) is 10-30 μm. This is used to generate a controllable change in the electrode spacing during pressure loading, while suppressing lateral crosstalk. The ZnO nanorods (302) have a center-to-center distance of 200-400 nm between adjacent rods, and the surface of the rod array is treated with oxygen plasma to introduce hydroxyl functional groups, which are used to improve the interfacial bonding strength with the ion gel (303) and reduce the contact resistance.

4. A dual-modal sensor based on a single unit according to claim 3, characterized in that: The ion gel (303) is composed of a crosslinked network of 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imine salt (EMIM-TFSI) and poly(2-hydroxyethyl acrylate) (PHEA), and is used to maintain resistance and temperature response in the range of -40°C to 120°C. The surface of the magnetic amorphous wire (304) is covered with a silicon dioxide insulating layer, and the wire axis is oriented by a magnetic field so that the direction of the wire axis is perpendicular to the radial direction of the annular electrode (402) to suppress magnetostriction interference when the temperature changes.

5. A dual-modal sensor based on a single unit according to claim 1, characterized in that: A telescopic rod (305) is installed between the intermediate sensitive layer (3) and the lower electrode layer (4). A damping spring (306) is installed on the outer ring of the telescopic rod (305). The top of the telescopic rod (305) is fixedly connected to the intermediate sensitive layer (3), and the bottom of the telescopic rod (305) is fixedly connected to both sides of the second circular electrode (401). This is used to guide the intermediate sensitive layer (3) to undergo controllable deformation in the vertical direction under pressure load, and to provide buffering through the damping spring (306).

6. A dual-modal sensor based on a single unit according to claim 1, characterized in that: The electrode materials of the upper electrode layer (2) and the lower electrode layer (4) are both Au and Cr double-layer thin films, and a moisture-proof insulating layer is vapor-deposited on the surface to prevent electrode oxidation and moisture erosion. Both the flexible upper substrate (1) and the flexible lower substrate (5) are polyimide films with a silicone rubber buffer layer spin-coated on their surface to enhance the flexibility of the device. A thermal actuator (501) is installed in the cavity of the flexible lower substrate (5). The thermal actuator (501) is electrically coupled to the lower electrode layer (4) and is used to provide local temperature excitation during temperature measurement.

7. A dual-mode sensor based on a single unit according to claim 1, characterized in that: The initial capacitance of the pressure-sensitive capacitor system is determined by the area and initial spacing of the first circular electrode (201) and the second circular electrode (401); the temperature-sensitive resistor system forms a ring resistance path between the second circular electrode (401) and the ring electrode (402), and its resistance changes accordingly with temperature.

8. A measurement method based on a single-unit dual-modal sensor, implemented using a single-unit dual-modal sensor as described in any one of claims 1-7, characterized in that, The method includes the following steps: Step S1: System initialization. In the initial state without external pressure and temperature stimulation, the reference capacitance value of the pressure-sensitive capacitor system composed of the first circular electrode (201) and the second circular electrode (401) and the reference resistance value of the temperature-sensitive resistor system composed of the second circular electrode (401) and the ring electrode (402) through the intermediate sensitive layer (3) are detected and recorded respectively, so as to provide a calculation reference for subsequent temperature and pressure change measurement. Step S2: Simultaneous acquisition and transmission of dual-modal signals. When the sensor senses external stimuli, it simultaneously acquires the output of two independent signal channels. The pressure-sensitive capacitor system generates a capacitance change signal because the intermediate sensitive layer (3) deforms and the distance between the plates changes due to pressure. The temperature-sensitive resistor system generates a resistance change signal because the ionic conductivity of the ion gel (303) or the resistivity of the magnetic amorphous wire (304) in the intermediate sensitive layer (3) changes due to temperature changes. The capacitance change signal and the resistance change signal are respectively transmitted to an external signal processing unit. Step S3, signal processing: based on the capacitance change signal and the pre-stored capacitance-pressure calibration curve, calculate and output the current absolute pressure value. This process utilizes the gradient pore size distribution characteristics of the gradient foam (301) to achieve a linear response. Based on the resistance change signal and the pre-stored resistance and temperature calibration curve, the current absolute temperature value is calculated and output. This process is dominated by the temperature-sensitive properties of the ion gel (303). The concentric structure of the second circular electrode (401) and the ring electrode (402) of the lower electrode layer (4) provides a physical basis for decoupling the two signals; Step S4, Signal Output and Display: The calculated absolute pressure and absolute temperature values ​​are output as independent data streams to the display unit or host computer system to complete the synchronous, dual-modal measurement of external temperature and pressure stimuli.

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