A flexible pressure-temperature dual-mode sensor

Abstract

The present invention discloses a flexible pressure-temperature dual-modal sensor, comprising a pressure-sensitive layer, a temperature-sensitive layer, and a PET substrate. Interdigitated electrodes are printed on both sides of the PET substrate, and the two interdigitated electrodes are connected by copper foil. The pressure-sensitive layer overlies one of the interdigitated electrodes to form a pressure sensing circuit, and the temperature-sensitive layer overlies the other interdigitated electrode to form a temperature sensing circuit. In this invention, the pressure-sensitive layer and the temperature-sensitive layer are combined via the PET substrate and the interdigitated electrodes to form a temperature sensing circuit and a pressure sensing circuit, thereby enabling simultaneous measurement of temperature and pressure.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a flexible pressure-temperature dual-mode sensor. Background Art

[0002] The explosive growth of artificial intelligence and the Internet of Things (IoT) has boosted public awareness of health and fostered a desire for smarter living, leading to a growing number of researchers devoting significant attention to the development of flexible sensors. The complex and multifaceted nature of external stimuli requires simultaneous sensing and discrimination to accurately reflect the shape of the object being measured. Multimodal flexible sensing is a key development trend in the development of future wearable electronics or electronic skin. The high precision, flexibility, and ease of integration of flexible sensors hold enormous potential for applications in areas such as human-computer interaction, intelligent robotics, and intelligent prosthetics.

[0003] Temperature and pressure are the most common physical parameters in our lives, providing us with information about weight, pressure, and temperature. Current sensors are mostly based on single sensing capabilities, and can only detect a single temperature or pressure function, namely, temperature sensors or pressure sensors. As our demand for complex scene detection increases, single sensors need to develop towards multifunctional flexible sensing. Currently, some dual-modal sensors based on heterogeneous working mechanisms have been reported, such as combined piezoelectric and thermoelectric, thermoelectric and piezoresistive effects, and ferroelectric and thermoelectric, which can achieve effective coupling of two signals. However, the two different working mechanisms often involve complex preparation and signal reading equipment, and may even cause signal crosstalk. Therefore, there is an urgent need for a flexible pressure-temperature dual-modal sensor. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a flexible pressure-temperature dual-modal sensor.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A flexible pressure-temperature dual-modal sensor includes a pressure-sensitive layer, a temperature-sensitive layer, and a PET substrate. Interdigital electrodes are printed on both sides of the PET substrate. The pressure-sensitive layer covers one of the interdigital electrodes to form a pressure sensing circuit, and the temperature-sensitive layer covers the other interdigital electrode to form a temperature sensing circuit. The two interdigital electrodes corresponding to the temperature sensing circuit and the pressure sensing circuit, respectively, are connected in series through copper foil to form a single signal output circuit.

[0007] The output signal of the signal output circuit is processed through the following steps to avoid crosstalk between the pressure signal and the temperature signal:

[0008] S4.1: Based on the characteristic differences between the temperature and pressure signals fed back by the temperature and pressure sensing circuits, the output signals are collected using a Keithley 4200A-SCS parameter analyzer to obtain current signals. The resulting Excel current table is exported, the header removed, and only the time and current columns are retained. The output signals include signals with only pressure response, only temperature response, and mixed pressure and temperature response.

[0009] S4.2: Use the tsfresh library to extract features from the two columns of data. The features extracted by tsfresh include: mean, variance, kurtosis, skewness, zero crossing rate, number of peaks, main frequency, and spectral energy;

[0010] S4.3: Classify the extracted features and convert each feature data after label classification into a standard normal distribution with a mean of 0 and a standard deviation of 1;

[0011] S4.4: Use PCA to reduce the dimensionality of feature data by finding the direction with the largest variance in the feature data and projecting the feature data to the direction with the largest variance.

[0012] S4.5: The feature data after dimensionality reduction is input into the random forest model for training, so that the random forest model learns the relationship between the classification label and the feature data to distinguish between temperature and pressure signals.

[0013] Preferably, the surface of the pressure sensitive layer in contact with the interdigital electrodes is a convex surface.

[0014] The steps for preparing the temperature sensitive layer are as follows:

[0015] S1.1. Pour polyvinyl pyrrolidone powder and cetyltrimethylammonium bromide into n-pentanol and fully dissolve them to obtain a mixed solution;

[0016] S1.2, pouring nickel oxide powder into the mixed solution, and obtaining a dispersed nickel oxide raw material by magnetic stirring and ultrasonic treatment;

[0017] S1.3. The dispersed nickel oxide raw material is dried to form a temperature sensitive layer.

[0018] The steps for preparing the pressure sensitive layer are as follows:

[0019] S2.1, ablating polyimide to obtain laser-induced graphene;

[0020] S2.2. Use sandpaper as a template for making the pressure-sensitive layer and clean the surface of the template;

[0021] S2.3, evenly applying laser-induced graphene on the surface of the template to form a laser-induced graphene layer, and applying polydimethylsiloxane on the surface of the laser-induced graphene layer;

[0022] S2.4. Dry the polydimethylsiloxane attached with laser-induced graphene and remove it from the template to form a pressure-sensitive layer.

[0023] Based on the above steps for preparing the temperature-sensitive layer and the pressure-sensitive layer, the steps for preparing the flexible pressure-temperature dual-modal sensor are as follows:

[0024] S3.1. Using a template, magnetron sputter gold interdigital electrodes are deposited on the upper and lower surfaces of a PET substrate. One of the pins of the two interdigital electrodes is connected by copper foil. The template is provided with sputtering grooves with the same pattern as the interdigital electrodes.

[0025] S3.2, applying the dispersed nickel oxide raw material to the interdigital electrodes on one side of the PET substrate and drying to form the temperature sensitive layer;

[0026] S3.3. Paste the pressure-sensitive layer on the interdigital electrodes on the other side of the PET substrate 3.

[0027] The PET substrate mentioned above is a type of thermoplastic polyester plastic with excellent toughness, tensile strength, impact strength, wear resistance, and electrical insulation. It has excellent tensile strength and tear resistance, enabling it to withstand mechanical stress. Polydimethylsiloxane is the main material for pressure sensors because of its good elasticity and flexibility, low elastic modulus and high ductility. The purpose of polyvinyl pyrrolidone powder is to bond nickel oxide nanopowder together to form a film. The high molecular weight polyvinyl pyrrolidone used in this experiment has high viscoelasticity. After being made into a film, it has a certain degree of flexibility and can be bent, thereby making the flexible pressure-temperature dual-modal sensor bendable.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The pressure-sensitive layer and temperature-sensitive layer provided in the present invention cooperate with each other through the PET substrate and the interdigital electrodes, and are combined together to form a temperature sensing circuit and a pressure sensing circuit, and the mechanism by which the resistance of the sensing circuit changes due to external signals is used to achieve simultaneous measurement of temperature and pressure.

[0030] 2. The present invention utilizes the flexibility of the PET substrate, the pressure-sensitive layer, the temperature-sensitive layer and the interdigital electrodes so that the manufactured flexible pressure-temperature dual-modal sensor can be bent during use.

[0031] 3. The temperature sensing circuit and the pressure sensing circuit in the present invention are connected by copper foil, so that the same output signal can reflect the temperature and pressure respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0033] Figure 2 It is a structural schematic diagram of the template of the present invention;

[0034] Figure 3 It is a schematic diagram of the working principle of the pressure sensing circuit of the present invention;

[0035] Figure 4 This is a temperature and pressure performance test diagram of the present invention under 4g, 25°C conditions;

[0036] Figure 5 This is a temperature and pressure performance test chart of the present invention under 8g, 25°C conditions;

[0037] Figure 6 This is a temperature and pressure performance test diagram of the present invention under 8g and 50°C conditions;

[0038] Figure 7 Schematic diagram of the current response and resistance temperature coefficient of the temperature sensing circuit of the present invention at different temperatures;

[0039] Figure 8 1 is a linear relationship diagram of the natural logarithm of the resistance ln(R) and 1000 / T of the temperature sensing circuit of the present invention at different temperatures;

[0040] Figure 9 Schematic diagram of the current response and pressure sensitivity of the pressure sensing circuit of the present invention under different pressures;

[0041] Figure 10 This is a graph showing the current attenuation change of the pressure sensing circuit of the present invention during a continuous cycle test;

[0042] Figure 11 It is the equivalent circuit of the present invention.

[0043] Figure symbols: 1. pressure-sensitive layer, 2. temperature-sensitive layer, 3. PET substrate, 4. interdigitated electrodes, 5. copper foil, 6. template, 61. sputtering tank. DETAILED DESCRIPTION

[0044] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0045] Example 1

[0046] like Figure 1 A flexible pressure-temperature dual-modal sensor shown includes a pressure-sensitive layer 1, a temperature-sensitive layer 2, and a PET substrate 3. Interdigitated electrodes 4 are printed on both sides of the PET substrate 3. The pressure-sensitive layer 1 covers one of the interdigitated electrodes 4 to form a pressure sensing circuit, and the temperature-sensitive layer 2 covers the other interdigitated electrode 4 to form a temperature sensing circuit. The two interdigitated electrodes 4 corresponding to the temperature sensing circuit and the pressure sensing circuit, respectively, are connected in series through copper foil 5 to form a single signal output circuit.

[0047] Specifically, the principle of the above pressure sensing circuit is as follows Figure 3 As shown, when the pressure sensitive layer 1 is squeezed downward, the contact area between the pressure sensitive layer 1 and the interdigital electrodes 4 in the pressure sensing circuit increases, and the conductive path of the pressure sensitive layer 1 becomes thicker. According to the resistance law:

[0048]

[0049] Wherein, S is the cross-sectional area of ​​the raised surface of the pressure-sensitive layer 1, ρ is the resistivity of the pressure-sensitive layer 1, and L is the length of the raised surface of the pressure-sensitive layer 1. It can be seen from the above formula (1) that when pressure is applied to the pressure-sensitive layer 1, the cross-sectional area of ​​the raised surface of the pressure-sensitive layer 1 increases, and the resistance of the pressure-sensitive layer 1 decreases. The pressure change can be obtained by the resistance change. Specifically, the surface of the pressure-sensitive layer 1 in contact with the interdigital electrode 4 is a convex surface, which ensures that the contact area between the pressure-sensitive layer 1 and the interdigital electrode 4 in the pressure sensing circuit changes more significantly when pressure is applied, thereby achieving high-precision pressure detection.

[0050] The temperature-sensitive layer 2 is a semiconductor material whose resistance changes with temperature. This change manifests as a negative temperature coefficient of resistance (TCR) characteristic, where the resistance decreases as the temperature increases. This is because the conductivity of a semiconductor is primarily determined by carriers, and an increase in temperature increases the carrier concentration or mobility of the semiconductor, leading to a negative TCR behavior. Temperature changes can be obtained through resistance changes.

[0051] During specific implementation, the object to be measured is directly placed on the flexible pressure-temperature dual-modal sensor and contacts the temperature-sensitive layer 2. At this time, the temperature sensing circuit directly senses the temperature of the object to be measured by using the principle that the temperature of the temperature-sensitive layer 2 increases and the resistance decreases; then the pressure change of the object to be measured will be transmitted to the pressure-sensitive layer 1. The pressure sensing circuit uses the deformation of the convex surface of the pressure-sensitive layer 1 under pressure to increase the contact area between the interdigital electrodes 4 in the pressure sensing circuit, the thickening of the conductive channel of the pressure-sensitive layer 1, and the deformation of the convex surface of the pressure-sensitive layer 1 under pressure, which will also cause the length of the microstructure to shorten and the conductive channel to thicken, so that the resistance decreases, thereby directly sensing the pressure applied to the pressure-sensitive layer 1 by the object to be measured.

[0052] The signal output by the above signal output circuit is processed through the following steps to avoid crosstalk between the pressure signal and the temperature signal:

[0053] S4.1: The temperature sensing circuit and the pressure sensing circuit differ in their sensing methods for stimulation signals. The pressure sensing circuit responds to stimulation signals in real time: when there is pressure, the current changes; when there is no pressure, the current change disappears immediately. However, the temperature sensing circuit responds to stimulation signals slowly: when there is stimulation, the current changes slowly until it reaches its highest point; when there is no stimulation, the current change slowly decreases, rather than disappearing immediately like the pressure sensing circuit. Therefore, the pressure sensing signal and the temperature sensing signal have significant characteristic differences. Next, signal acquisition is performed. Specifically, based on the characteristic differences between the temperature signal and the pressure signal fed back by the temperature sensing circuit and the pressure sensing circuit, the output signal is acquired using a Keithley 4200A-SCS parameter analyzer to obtain a current signal. Specifically, the output signal includes a signal that responds only to pressure, a signal that responds only to temperature, and a signal that responds to both pressure and temperature. 100 groups of each of the pressure response signal, the temperature response signal, and the pressure and temperature response signal are collected. The resulting Excel current table is exported, the header is removed, and only the time and current columns of data are retained.

[0054] S4.2: Use the tsfresh library to perform feature extraction on the two columns of data. The features extracted by tsfresh include: mean, variance, kurtosis, skewness, zero crossing rate, number of peaks, main frequency, and spectrum energy;

[0055] S4.3: Classify the extracted features and convert each feature data after label classification into a standard normal distribution with a mean of 0 and a standard deviation of 1;

[0056] S4.4: Use PCA to reduce the dimensionality of feature data by finding the direction with the largest variance in the feature data and projecting the feature data to the direction with the largest variance.

[0057] S4.5: Input the reduced feature data into the random forest model for training, so that the random forest model can learn the relationship between the classification label and the feature data to distinguish between temperature and pressure signals. The specific steps are as follows:

[0058] Model parameter settings: Set the number of decision trees of the random forest, the maximum depth of each tree, the minimum number of samples required to split a node, and the minimum number of samples required for a node. Specifically, set the number of decision trees of the random forest to 50, the maximum depth of each tree to 10, the minimum number of samples required to split a node to 2, and the minimum number of samples required for a node to 1;

[0059] Training model: Input the reduced feature data for training, so that the random forest model can learn the relationship between category labels and features. Next, we input the test signal. The model will classify the test set we input, and then we can get the type of input signal and distinguish between temperature and pressure signals.

[0060] Example 2

[0061] The temperature sensitive layer 2 and the pressure sensitive layer 1 are made of two different materials, and cooperate with the two interdigital electrodes 4 to sense the temperature and / or pressure of the object being measured simultaneously or separately without input signal crosstalk.

[0062] The steps for preparing the pressure sensitive layer 1 are as follows:

[0063] S2.1, ablation of polyimide by CO2 infrared laser to obtain laser-induced graphene;

[0064] S2.2. Use 120-grit sandpaper as a template for making pressure-sensitive layer 1, and use a nitrogen gun to purge the surface of the template to remove contaminants.

[0065] S2.3. Evenly apply laser-induced graphene on the surface of the template to form a laser-induced graphene layer. Apply polydimethylsiloxane on the surface of the laser-induced graphene layer and scrape off excess polydimethylsiloxane with a scraper to obtain a film with a thickness of 0.8 mm.

[0066] S2.4. After drying in an oven for 6 hours, the polydimethylsiloxane with laser-induced graphene attached is removed from the template to form a pressure-sensitive layer 1, and the surface of the pressure-sensitive layer 1 corresponding to the interdigitated electrode 4 is a convex surface. Specifically, the laser-induced graphene has good conductivity, and its sheet shape makes the surface area large. It has a certain flexibility after ablation. The ablated laser-induced graphene and polydimethylsiloxane, that is, PDMS, cooperate with each other to form a pressure-sensitive layer 1. The low elastic modulus and high ductility of PDMS (deformation under pressure, recovery to original shape under decompression) cooperate with the interdigitated electrode 1 to form a pressure sensing circuit. At the same time, the elasticity and flexibility of PDMS cooperate with the flexibility of laser-induced graphene after ablation, so that the pressure sensing circuit can be deformed.

[0067] The steps for preparing the temperature sensitive layer 2 are as follows:

[0068] S1.1. Pour 0.68 g of polyvinyl pyrrolidone powder with a molecular weight of 40,000 and 0.05 g of cetyl trimethyl ammonium bromide with a particle size of 30 nm into 7.5 ml of n-pentanol and stir magnetically for 5 h to fully dissolve to obtain a mixed solution. The cetyl trimethyl ammonium bromide enhances the dispersion stability of polyvinyl pyrrolidone in n-pentanol.

[0069] S1.2. Pour 3.1 g of nickel oxide powder into the above mixture, stir magnetically for 2 h, and ultrasonicate for 5 min to obtain a dispersed nickel oxide raw material for preparing the temperature-sensitive layer 2. Polyvinyl pyrrolidone ensures the viscosity of the nickel oxide raw material and provides sufficient surface tension to enable the nickel oxide to form a film.

[0070] S1.3. Use a rubber-tipped dropper to absorb the dispersed nickel oxide raw material, drop a drop on the PET substrate 3 with the interdigital electrodes 4, and dry it in a 60°C oven for 3 hours to form a nickel oxide film. The nickel oxide film serves as the temperature-sensitive layer 2. The flexibility of the film allows the temperature sensing circuit formed by the cooperation between the temperature-sensitive layer 2 and the interdigital electrodes 4 to be deformed.

[0071] The preparation steps of the flexible pressure-temperature dual-mode sensor are as follows:

[0072] S3.1, such as Figure 2 As shown, a template 6 is used to sputter gold interdigital electrodes 4 with a thickness of 20 nm on the upper and lower surfaces of the PET substrate 3 by magnetron sputtering, and one of the pins of the two interdigital electrodes 4 is connected through a copper foil 5, as shown in FIG. Figure 2As shown, the template 6 is provided with a sputtering groove 61 having the same pattern as the interdigital electrode 4, wherein the interdigital electrode 4 is supported by gold, which has the characteristics of high conductivity, high chemical inertness, high stability, and low contact resistance. The copper foil 5 is a copper foil tape, which has good flexibility, can adapt to irregular surfaces, and is easy to be attached to objects of complex shapes;

[0073] S3.2, applying the dispersed nickel oxide raw material to the interdigitated electrodes 4 on one side of the PET substrate 3, and drying to form the temperature sensitive layer 2;

[0074] S3.3. Paste the pressure-sensitive layer 1 onto the interdigital electrodes 4 on the other side of the PET substrate 3 to form the above-mentioned flexible pressure-temperature dual-modal sensor.

[0075] The above-mentioned PET substrate is made of PET plastic. PET plastic is a thermoplastic polyester with toughness, high tensile and impact strength, electrical insulation, tensile strength and tear resistance. The flexible pressure-temperature dual-modal sensor formed by cooperating with the deformable temperature sensing circuit and pressure sensing circuit also has the ability to deform. Moreover, since the temperature-sensitive layer 2 constituting the temperature sensing circuit is a film, the characteristic of the film having a small elastic deformation when under pressure is utilized, so that the temperature sensing circuit is almost unaffected when the pressure sensing circuit is in operation. Moreover, when the temperature sensing circuit is in operation, due to the obstruction of the PET substrate 3, heat energy is difficult to be transferred to the pressure-sensitive layer 1, thereby making the operation of the pressure sensing circuit almost unaffected by the operation of the temperature sensing circuit. Therefore, the input signal of the above-mentioned flexible pressure-temperature dual-modal sensor will not be crosstalked during operation.

[0076] Verification Example

[0077] The PET substrate 3 of the flexible pressure-temperature dual-modal sensor is made of a PET transparent plastic film with a thickness of 0.4 mm and a size of 20 mm*20 mm.

[0078] Perform temperature and pressure performance measurements:

[0079] Water of different masses and temperatures is placed in a transparent glass bottle, which is then placed on the temperature-pressure dual-modal sensor. The temperature and pressure sensing performance are measured as the bottle is picked up and placed down.

[0080] Specifically, when the bottle is filled with 4g of water at 25℃, the temperature and pressure performance test results are as follows: Figure 4 As shown, it can be seen that the current change of the temperature signal has almost no change, but the current change of the pressure signal has a huge change.

[0081] When the bottle is filled with 8g of water at 25℃, the temperature and pressure performance test results are shown in the figure below. Figure 5As shown in the figure, the current variation of the temperature signal remains unchanged, but the current variation of the pressure signal almost doubles.

[0082] When the bottle is filled with 8g of water at 50℃, the temperature and pressure performance test results are shown in the figure below. Figure 6 As shown in Figure 2, the current of the temperature signal has changed significantly, but the current change of the pressure signal is Figure 5 resemblance.

[0083] In summary, the temperature-pressure dual-modal sensor disclosed in the present invention can detect both the change in pressure signal and the change in temperature signal.

[0084] Specifically, the room temperature during the measurement was approximately 27°C, and the glass sample bottle used contained tap water at approximately 25°C. When these two samples came into contact, the temperature sensor sensed the cold temperature, and the current experienced a small but noticeable decrease, similar to a downward jitter. At the same pressure and different temperatures, the pressure signal was unaffected by temperature, and while the pressure signal's peaks exhibited jitter, the current change was approximately 10,000, which is the same order of magnitude and similar in value.

[0085] The circuit equivalent diagram is as follows Figure 11 As shown in the figure, the temperature sensor and pressure sensor are actually two components. Because they are based on different materials, they are just connected in series and only respond to a single signal, so they have no crosstalk.

[0086] When performing temperature performance measurements:

[0087] The current response of the temperature sensing circuit at different temperatures and the temperature coefficient of resistance (TCR) at different temperature ranges are as follows: Figure 7 As shown in the figure, the resistance of the temperature sensing circuit decreases gradually with the increase of temperature, and has the largest TCR coefficient in the low temperature range of 25-45℃, reaching -4.70%℃ -1 , and then as the temperature rises, the resistance change trend gradually slows down.

[0088] By fitting the curve, it is obtained that the temperature sensitive layer 2 has an excellent thermal constant of 13015K in the temperature range (25-45°C), which far exceeds the standard of commercial thermistors (3500K).

[0089] To perform pressure performance measurements:

[0090] The current response of the pressure sensing circuit under different pressures and the pressure sensitivity (S) under different pressure ranges are as follows: Figure 9 As shown, within the pressure range of 0.12-1.86kPa, the sensitivity is 1592kPa -1; In the pressure range of 1.86-19.85kPa, the sensitivity is 28086kPa -1 ; In the pressure range of 19.52-49kPa, the sensitivity is 7062kPa -1 .

[0091] In summary, the pressure sensing circuit shows excellent sensing performance.

[0092] Cyclic durability measurement of the pressure sensing part:

[0093] The linear motor is used to apply pressure to the pressure sensitive layer 1. Specifically, when the pressure sensitive layer 1 is pressed and released for more than 10 cycles, 4 In this test, the current signal of the pressure sensing circuit decays as follows Figure 10 As shown, there is no obvious current decay in the continuous cycles, indicating that the pressure sensing circuit has excellent durability.

[0094] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A flexible pressure-temperature dual-mode sensor, characterized in that: The invention comprises a pressure-sensitive layer (1), a temperature-sensitive layer (2) and a PET substrate (3), wherein both sides of the PET substrate (3) are printed with interdigital electrodes (4), the pressure-sensitive layer (1) covers one of the interdigital electrodes (4) to form a pressure sensing circuit, and the temperature-sensitive layer (2) covers the other interdigital electrode (4) to form a temperature sensing circuit, and the two interdigital electrodes (4) corresponding to the temperature sensing circuit and the pressure sensing circuit are connected in series through copper foil (5) to form a single signal output circuit; The output signal of the signal output circuit is processed by the following steps to avoid crosstalk between the pressure signal and the temperature signal: S4.1: Based on the characteristic differences between the temperature and pressure signals fed back by the temperature and pressure sensing circuits, the output signals are collected using a Keithley 4200A-SCS parameter analyzer to obtain current signals. The resulting Excel current table is exported, the table header removed, and only the time and current columns are retained; S4.2: Use the tsfresh library to perform feature extraction on the two columns of data. The features extracted by tsfresh include: mean, variance, kurtosis, skewness, zero crossing rate, number of peaks, main frequency, and spectrum energy; S4.3: Classify the extracted features and convert each feature data after label classification into a standard normal distribution with a mean of 0 and a standard deviation of 1; S4.4: Use PCA to reduce the dimensionality of feature data by finding the direction with the largest variance in the feature data and projecting the feature data to the direction with the largest variance. S4.5: The feature data after dimensionality reduction is input into the random forest model for training, so that the random forest model learns the relationship between the classification label and the feature data to distinguish between temperature and pressure signals.

2. The flexible pressure-temperature dual-mode sensor according to claim 1, characterized in that: The output signals include signals that respond only to pressure, signals that respond only to temperature, and signals that respond in combination with pressure and temperature.

3. The flexible pressure-temperature dual-mode sensor according to claim 2, characterized in that: The surface of the pressure-sensitive layer (1) in contact with the interdigital electrodes (4) is a convex surface.

4. The flexible pressure-temperature dual-mode sensor according to claim 3, characterized in that: The steps for preparing the temperature sensitive layer (2) are as follows: S1.

1. Pour polyvinyl pyrrolidone powder and cetyltrimethylammonium bromide into n-pentanol and fully dissolve them to obtain a mixed solution; S1.2, pouring nickel oxide powder into the mixed solution, and obtaining a dispersed nickel oxide raw material by magnetic stirring and ultrasonic treatment; S1.

3. The dispersed nickel oxide raw material is dried to form the temperature sensitive layer (2).

5. The flexible pressure-temperature dual-mode sensor according to any one of claims 2 to 4, characterized in that: The steps for preparing the pressure sensitive layer (1) are as follows: S2.1, ablating polyimide to obtain laser-induced graphene; S2.2, using sandpaper as a template for manufacturing the pressure-sensitive layer (1), and cleaning the surface of the template; S2.3, evenly applying the laser-induced graphene on the surface of the template to form a laser-induced graphene layer, wherein the surface of the laser-induced graphene layer is coated with polydimethylsiloxane; S2.

4. Dry the polydimethylsiloxane attached with laser-induced graphene and remove it from the template to form the pressure-sensitive layer (1).

6. The flexible pressure-temperature dual-mode sensor according to claim 5, characterized in that: The preparation steps of the flexible pressure-temperature dual-modal sensor are as follows: S3.

1. Using a template (6), gold interdigital electrodes (4) are sputtered on the upper and lower surfaces of the PET substrate (3) by magnetron sputtering, and one of the pins of the two interdigital electrodes (4) is connected through a copper foil (5); S3.2, applying the dispersed nickel oxide raw material on the interdigitated electrode (4) on one side of the PET substrate (3), and drying to form the temperature sensitive layer (2); S3.

3. Paste the pressure-sensitive layer (1) onto the interdigital electrodes (4) on the other side of the PET substrate 3.

7. The flexible pressure-temperature dual-mode sensor according to claim 6, characterized in that: The template (6) is provided with a sputtering groove (61) having the same pattern as the interdigital electrode (4).

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