Preparation method of wide-range self-adapting heterogeneous conductive fabric pressure sensor and sensor

Abstract

The application provides a preparation method of a wide-range self-adaptive heterogeneous conductive fabric pressure sensor and the sensor, and particularly relates to the technical field of flexible sensors. The method comprises the following steps: S1, determining a multi-layer fiber laminated structure as a main structure of the heterogeneous conductive fabric pressure sensor; S2, constructing an equivalent resistance ratio model based on a multi-stage heterogeneous conductive network; S3, determining a target resistance ratio that can make the linearity of the heterogeneous conductive fabric pressure sensor reach a target; and S4, preparing and assembling the heterogeneous conductive fabric pressure sensor. The application adopts a multi-layer heterogeneous conductive design, effectively solves the technical problems that the sensitivity and linearity of the existing fabric pressure sensor are difficult to be considered in a wide pressure range, and the wearing comfort is low and the fit is poor due to the adoption of a rigid structure.

Description

Technical Field

[0001] This invention relates to the field of flexible sensor technology, specifically to a method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor and the sensor itself. Background Technology

[0002] Flexible sensors, due to their excellent biocompatibility and stronger bending deformation capabilities, show broad application prospects in fields such as health monitoring, flexible robotics, and human-computer interaction. However, flexible sensors still face two key challenges in practical applications: First, achieving both high sensitivity and high linearity across a wide pressure range remains challenging. Many existing flexible sensors typically consist of a single layer of conductive material coated across the entire fabric surface. This conductive network readily saturates under pressure, resulting in response curves exhibiting pronounced nonlinear characteristics—high sensitivity at low pressures but significantly reduced sensitivity at medium to high pressures. This nonlinear response severely limits the sensor's application over a wide pressure range requiring precise measurements and places a significant burden on subsequent signal calibration and processing.

[0003] Secondly, in pursuit of high performance, some existing flexible sensors often adopt a composite structure of "rigid functional module + flexible packaging". This type of rigid-flexible hybrid sensor not only destroys the original softness and breathability of the fabric, but also, when faced with complex curved surface bonding and long-term dynamic bending, there is a modulus mismatch between the rigid element and the flexible substrate. This can easily lead to device breakage or failure due to interface stress concentration, and cannot meet the requirements of long-term comfortable wear and high-reliability deformation.

[0004] In summary, in order to overcome the aforementioned technical bottlenecks, it is urgent to develop a fabric pressure sensor with a large range, wide linear range, and fully flexible structure, as well as its fabrication method, to expand its practical value in complex scenarios such as outdoor sports, medical monitoring, and underwater operations. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention aims to provide a method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor and the sensor itself. This invention addresses the problems of existing fabric pressure sensors being unable to simultaneously achieve high sensitivity and high linearity over a wide pressure range, as well as the technical difficulties of low wearing comfort and poor fit caused by the use of rigid structures.

[0006] Specifically, on the one hand, the present invention provides a method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor, which includes the following steps: S1. The multi-layer fiber stacked structure is determined as the main structure of the heterogeneous conductive fabric pressure sensor. Its structure, from bottom to top, includes: fabric base layer, first conductive layer, second conductive layer and top protective layer; the fabric base layer is provided with interdigitated electrodes for signal acquisition and transmission. S2. Conduct pressure sensing mechanism analysis and construct an equivalent resistance ratio model based on a multi-level heterogeneous conductive network; S21. Analyze the current transmission path of the heterogeneous conductive fabric pressure sensor under different pressure stages, and construct a macroscopic equivalent resistance expression that can reflect the resistance change law. ; Among them, R macro (P) represents the macroscopic equivalent resistance under pressure P; P is the external pressure; R c1 (P) represents the first contact resistance under pressure P; R m R is the first microscopic resistance; m is the number of first microscopic points; c2 (P) represents the second contact resistance under pressure P; f(P) is the medium-pressure conductivity weighting function; g(P) is the high-pressure shunt function; n is the number of second micro-points; λ is the resistance matching coefficient; S22. Based on the macroscopic equivalent resistance expression obtained in S21, the evolution law of current transmission and shunting of the heterogeneous conductive fabric pressure sensor in different pressure ranges is analyzed to obtain the equivalent resistance ratio expression. ; Where λopt is the optimal resistance matching coefficient; For the first nonlinearity, For the second nonlinearity, This is the shunt enhancement rate during the high-voltage phase; S3. Based on the equivalent resistance ratio formula of S2, determine the optimal resistance ratio range, and combine it with the wide-range pressure loading test to determine the target resistance ratio that can make the linearity of the heterogeneous conductive fabric pressure sensor reach. S4. Based on the heterogeneous conductive fabric pressure sensor structure determined in S1, and combined with the target resistance ratio determined in S3, the heterogeneous conductive fabric pressure sensor is prepared and assembled.

[0007] Preferably, step S21 includes: S211. Analyze the resistance of the heterogeneous conductive fabric pressure sensor under low pressure to obtain the low-pressure resistance of the heterogeneous conductive fabric pressure sensor. S212. Analyze the resistance of the heterogeneous conductive fabric pressure sensor under medium pressure to obtain the medium pressure resistance of the heterogeneous conductive fabric pressure sensor. S213. Analyze the resistance of the heterogeneous conductive fabric pressure sensor under high pressure to obtain the macroscopic high pressure resistance of the heterogeneous conductive fabric pressure sensor. S214, combined with the low-voltage resistor obtained from S211, the medium-voltage resistor obtained from S212, and the macroscopic high-voltage resistor obtained from S213, yields the macroscopic equivalent resistance of the heterogeneous conductive fabric pressure sensor.

[0008] Preferably, the low-voltage resistor R of the heterogeneous conductive fabric pressure sensor 低 for: Among them, R HB R is the bulk resistance of the first conductive layer. c1 The first contact resistance; Medium pressure resistance R of heterogeneous conductive fabric pressure sensor 中 for: =2 + + ; in, This is the second contact resistance.

[0009] Preferably, step S213 includes: S2131. Analyze the resistance of the micro-viewpoint positioning of the heterogeneous conductive fabric pressure sensor under high pressure to obtain the high-voltage resistance R of the micro-viewpoint positioning of the heterogeneous conductive fabric pressure sensor. eq : ; S2132. Based on the current shunting mechanism and combined with the micro-view high-voltage resistor obtained in S2131, the macroscopic resistance of the heterogeneous conductive fabric pressure sensor under high voltage is analyzed to obtain the macroscopic high-voltage resistance of the heterogeneous conductive fabric pressure sensor.

[0010] Preferably, step S3 specifically includes: S31. Based on the macroscopic equivalent resistance ratio expression of S2, determine the range of resistance ratios between the first and second conductive layers that enables the linearity of the heterogeneous conductive fabric pressure sensor: , ; Where k1 is the first resistor matching tolerance coefficient and k2 is the second resistor matching tolerance coefficient; S32. Based on the resistance ratio range between the first conductive layer and the second conductive layer determined in S31, a wide-range pressure loading test is performed to determine the target resistance ratio that enables the linearity of the heterogeneous conductive fabric pressure sensor to be achieved.

[0011] Preferably, step S4 includes: S41. A two-step chemical method is used to hydrophobically treat the fabric base layer and top protective layer to make the fabric base layer and top protective layer hydrophobic. S42. Using screen printing, the interdigitated electrode template prepared by laser processing is printed onto the surface of the fabric substrate layer to obtain a fabric substrate layer with interdigitated electrodes. S43. The first conductive layer and the second conductive layer are immersed in colloidal solutions of different concentrations and then dried to obtain the first conductive layer and the second conductive layer with different bulk resistances. S44. Based on the main structure of the heterogeneous conductive fabric pressure sensor determined in S1, the prepared fabric base layer, first conductive layer, second conductive layer and top protective layer are stacked in sequence, and the edges are sealed and fixed to obtain the heterogeneous conductive fabric pressure sensor.

[0012] Preferably, the volume resistance ratio of the first conductive layer to the second conductive layer is in the range of 60 to 80.

[0013] Preferably, the linearity of the heterogeneous conductive fabric pressure sensor is optimal when the contact between the first conductive layer and the fabric substrate electrode approaches saturation and the shunting of the second conductive layer is enhanced.

[0014] Preferably, the macroscopic high-voltage resistor value R(P) in step S2132 is: ; Where x(P) represents the number of the first and second effective conductive contact points under pressure P.

[0015] In a second aspect, the present invention provides a heterogeneous conductive fabric pressure sensor, the main structure of which is a multilayer fiber stacked structure, comprising, from bottom to top: a fabric base layer, a first conductive layer, a second conductive layer, and a top protective layer; the fabric base layer is provided with interdigitated electrodes for signal acquisition and transmission; wherein, the fabric base layer is a superhydrophobic polyester base layer, the first conductive layer is a high sheet resistance conductive cotton fabric layer, the second conductive layer is a low sheet resistance conductive cotton fabric layer, and the top protective layer is a superhydrophobic polyester protective layer.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention introduces a multi-layer heterogeneous conductive design to construct a multi-level conductive network in the same fabric system where high sheet resistance and low sheet resistance coexist. This allows the current transmission path to switch stepwise between different scales and different conductive layers as the pressure increases, thereby achieving a high linearity response over a wide pressure range and significantly alleviating the sensitivity decay problem caused by the easy saturation of a single conductive network.

[0017] 2. This invention employs a purely flexible structure design made entirely of fiber fabric, abandoning traditional rigid sensing units or hard circuit boards. This gives the sensor extremely high mechanical compliance, enabling seamless conformal contact with human skin and complex mechanical surfaces, providing a comfortable wearing experience without any foreign body sensation. It also fully retains the physical properties of textiles, such as bend resistance, customizability, and washability, significantly improving the long-term reliability of the flexible sensor in dynamic wearable scenarios. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the heterogeneous conductive fabric pressure sensor of the present invention; Figure 2 This is a schematic diagram illustrating the electrical characteristics of the heterogeneous conductive fabric pressure sensor of the present invention. Figure 3 This is a schematic diagram of the sensing mechanism of the heterogeneous conductive fabric pressure sensor of the present invention under different pressure stages. Figure 4 This is a schematic diagram illustrating the performance changes of the heterogeneous conductive fabric pressure sensor of the present invention. Figure 5 This is a schematic diagram of the fabrication process of the multilayer stacked structure of the heterogeneous conductive fabric pressure sensor of the present invention. Figure 6 This is a schematic diagram characterizing the thickness of the MXene material of the present invention; Figure 7 The above are the EDS energy spectrum of the fabric surface after impregnation with MXene solution according to the present invention and the corresponding appearance schematic diagram. Figure 8 The graph shows the linearity test results of the single-layer conductive fabric pressure sensor of the present invention. Figure 9 The graph shows the linearity test results of the heterogeneous conductive fabric pressure sensor of the present invention. Figure 10 This is a comparison diagram of the linearity of the single-layer conductive fabric pressure sensor and the heterogeneous conductive fabric pressure sensor of the present invention. Figure 11 The graph shows the sensitivity test results of the heterogeneous conductive fabric pressure sensor of the present invention. Figure 12 The graph shows the test results of the response time and recovery time of the heterogeneous conductive fabric pressure sensor of the present invention. Figure 13 The graph shows the dynamic response test results of the heterogeneous conductive fabric pressure sensor of the present invention at different loading frequencies. Figure 14 The diagram shows the surface contact angle and droplet dynamic behavior of the fabric base layer and top protective layer of the present invention under untreated, single chemical treatment and two-step chemical treatment conditions. Figure 15The image shows the contact angle test results of the fabric surface under different liquid conditions after the fabric base layer and top protective layer of the present invention have undergone two-step chemical treatment. Figure 16 This is a schematic diagram illustrating the endurance of the heterogeneous conductive fabric pressure sensor of the present invention. Figure 17 This is a response performance diagram of the heterogeneous conductive fabric pressure sensor of the present invention. Figure 18 This is a schematic diagram illustrating the application of the heterogeneous conductive fabric pressure sensor of the present invention. Figure 19 This is an application test diagram of the heterogeneous conductive fabric pressure sensor of the present invention; Figure 20 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0019] This invention employs a multi-layer heterogeneous conductive design, which effectively solves the technical problems of existing fabric pressure sensors, such as difficulty in achieving both sensitivity and linearity over a wide pressure range, as well as the low wearing comfort and poor fit caused by the use of rigid structures.

[0020] Specifically, the present invention is as follows Figure 20 As shown, it includes the following steps: S1. The multi-layer fiber stacked structure is determined as the main structure of the heterogeneous conductive fabric pressure sensor. Its structure, from bottom to top, includes: fabric base layer, first conductive layer, second conductive layer and top protective layer; the fabric base layer is provided with interdigitated electrodes for signal acquisition and transmission. Specifically, such as Figure 1 As shown, the fabric base layer is a superhydrophobic polyester base layer, the first conductive layer is a high sheet resistance conductive cotton fabric layer, the second conductive layer is a low sheet resistance conductive cotton fabric layer, and the top protective layer is a superhydrophobic polyester protective layer.

[0021] S2. Conduct pressure sensing mechanism analysis and construct an equivalent resistance ratio model based on a multi-level heterogeneous conductive network.

[0022] like Figure 2 As shown, when the external pressure applied to the heterogeneous conductive fabric pressure sensor is relatively small, the current mainly flows through the first conductive layer with high sheet resistance. The yarn pores of the fibers in the first and second conductive layers shrink rapidly, causing a change in resistance and achieving high-sensitivity pressure sensing. When the pressure continues to increase, the fiber structure of the heterogeneous conductive fabric pressure sensor collapses further, and the second conductive layer with low sheet resistance gradually forms a through-type dominant conductive path, thereby achieving pressure sensing over a large range and a wide linear range.

[0023] S21. Analyze the current transmission path of the heterogeneous conductive fabric pressure sensor under different pressure stages, and construct a macroscopic equivalent resistance expression that can reflect the resistance change law.

[0024] like Figure 4 As shown, the heterogeneous conductive fabric pressure sensor, compared to sensors with a single microstructure or a single conductive layer substrate, allows the current transmission path to switch with pressure changes, thereby maintaining high linearity over a wider pressure range. At the same time, the upper and lower encapsulation fabric layers are superhydrophobic surfaces, enabling the heterogeneous conductive fabric pressure sensor to maintain stable output even in aquatic environments.

[0025] like Figure 3 As shown, Figure 3 a represents the low-pressure state of the heterogeneous conductive fabric pressure sensor; Figure 3 b represents the medium pressure state of the heterogeneous conductive fabric pressure sensor; Figure 3 c represents the high-pressure state of the heterogeneous conductive fabric pressure sensor.

[0026] The resistance matching coefficient λ, which characterizes the resistance matching relationship between the first conductive layer and the second conductive layer, is defined as follows: ; Among them, R HB R is the bulk resistance of the first conductive layer. LB This represents the bulk resistance of the second conductive layer.

[0027] S211. Analyze the resistance of the heterogeneous conductive fabric pressure sensor under low pressure to obtain the low-pressure resistance of the heterogeneous conductive fabric pressure sensor.

[0028] like Figure 3 As shown in Figure a, when the pressure sensor of the heterogeneous conductive fabric is in a low-pressure state, the external pressure is small, resulting in very little contact between the first conductive layer and the second conductive layer. At this time, the resistance of the heterogeneous conductive fabric pressure sensor is the sum of the contact resistance between the first conductive layer and the fabric substrate layer and the bulk resistance of the first conductive layer.

[0029] in, For a pressure sensor made of heterogeneous conductive fabric, the low-voltage resistor R c1 R is the first contact resistance. HB The first conductive layer has a bulk resistance.

[0030] Specifically, the first contact resistance characterizes the contact resistance between the first conductive layer and the fabric substrate electrode.

[0031] During the low-pressure phase, the response of the heterogeneous conductive fabric pressure sensor is mainly determined by the contact state between the first conductive layer and the electrode, as well as the resistance of the first conductive layer itself. Since the second conductive layer has not yet formed an effective conductive path, the resistance matching coefficient λ has a relatively small direct impact on the total resistance during this phase.

[0032] S212. Analyze the resistance of the heterogeneous conductive fabric pressure sensor under medium pressure to obtain the medium pressure resistance of the heterogeneous conductive fabric pressure sensor.

[0033] like Figure 3 As shown in Figure b, with the increase of external pressure, the contact between the first conductive layer and the fabric substrate increases in the heterogeneous conductive fabric pressure sensor under medium pressure, and the contact between the first conductive layer and the second conductive layer also increases, resulting in a rapid decrease in contact resistance. However, at this time, the interlayer current shunt is still not strong enough, and the current is still mainly borne by the first conductive layer.

[0034] At this time, the resistance of the heterogeneous conductive fabric pressure sensor is the sum of the contact resistance between the first conductive layer and the fabric substrate, the contact resistance between the first conductive layer and the second conductive layer, and the bulk resistance of the first conductive layer.

[0035] =2 + + ; in, The medium-pressure resistor is used in a pressure sensor made of heterogeneous conductive fabric. This is the second contact resistance.

[0036] Specifically, the second contact resistance Characterizes the interlayer contact resistance between the first conductive layer and the second conductive layer.

[0037] The medium-pressure stage is the transitional phase where the resistance matching coefficient λ begins to play a regulatory role. When the resistance matching coefficient λ is small, it indicates that the resistance difference between the first and second conductive layers is small, and the second conductive layer is more likely to participate in conduction prematurely, causing the total resistance to drop too quickly in the medium-pressure stage, which may weaken the overall linearity. When the resistance matching coefficient λ is large, the pressure threshold for the second conductive layer to participate in conduction increases, and the heterogeneous conductive fabric pressure sensor still mainly relies on the response of the first conductive layer in the medium-pressure stage, which helps to avoid premature current shunting. However, if the resistance matching coefficient λ is too large, it may lead to insufficient current shunting in the subsequent high-pressure stage.

[0038] S213. The resistance of the heterogeneous conductive fabric pressure sensor under high pressure is analyzed to obtain the macroscopic high-pressure resistance of the heterogeneous conductive fabric pressure sensor: S2131. The resistance of the micro-viewpoint positioning of the heterogeneous conductive fabric pressure sensor under high pressure is analyzed to obtain the high-voltage resistance of the micro-viewpoint positioning of the heterogeneous conductive fabric pressure sensor: like Figure 3 As shown in Figure c, with the increase of external pressure, when the heterogeneous conductive fabric pressure sensor is under high pressure, the contact between the first conductive layer and the fabric substrate layer tends to saturate, meaning the contact resistance between the first conductive layer and the electrode tends to stabilize. Simultaneously, the contact area between the first and second conductive layers gradually increases. Because the resistance of the second conductive layer is significantly lower than that of the first conductive layer, current tends to flow towards the lower-resistance second conductive layer.

[0039] That is, when the fabric base layer, the first conductive layer, and the second conductive layer form a contact point, the current flow direction at the contact point is as follows: (1) Flowing along the first conductive layer, the resistance is the resistance value of a single resistive unit in the second conductive layer; (2) The flow transfers to the second layer, and the resistance is the resistance of a single resistive unit in the first conductive layer plus the interlayer contact impedance. The local equivalent resistance at the contact point can then be expressed as: Assume the first conductive layer consists of m first micro-point positioning resistors, and the second conductive layer consists of n second micro-point positioning resistors. That is, when the fabric substrate, the first conductive layer, and the second conductive layer form a contact point, the current flow at the contact point is as follows: 1) Flowing along the first conductive layer, with resistance equal to the first micro-point positioning resistor. 2) Flowing to the second layer, with resistance equal to the second micro-point positioning resistor plus the interlayer contact impedance.

[0040] If the interlayer transfer impedance at the contact point is incorporated The path, then the micro-level high-voltage resistance at the contact point is : ; Among them, R m R is the first microscopic resistance. n This is the second microscopic resistance.

[0041] S2132. Based on the current shunting mechanism and combined with the micro-view high-voltage resistance obtained in S2131, the macroscopic resistance of the heterogeneous conductive fabric pressure sensor under high voltage is analyzed to obtain the macroscopic high-voltage resistance of the heterogeneous conductive fabric pressure sensor: Specifically, if x(P) effective contact points are formed under high voltage, then: x(P) segments of the region form parallel conduction, that is, there are x(P) series micro-point positioning high voltage resistors, and the remaining uncontacted part is still a series high resistance path, corresponding to a total contribution of mx(P) series first micro-point positioning resistors.

[0042] The macroscopic high-voltage resistance can then be expressed as: ; Where R(P) is the macroscopic high-pressure resistance value at pressure P, P is the external pressure, and Rc1 (P) represents the first contact resistance under pressure P, m represents the number of first micro-points, and x(P) represents the number of first and second effective conductive contact points under pressure P.

[0043] Further analysis revealed: .

[0044] According to the definition in S2131, mRm=R HB Therefore, the final value of the macroscopic high-voltage resistor can be expressed as: .

[0045] S214, combining the low-voltage resistor obtained from S211, the medium-voltage resistor obtained from S212, and the macroscopic high-voltage resistor obtained from S213, yields the macroscopic equivalent resistance R of the heterogeneous conductive fabric pressure sensor. macro (P): ; Where f(P) is the medium-voltage conductivity weighting function, g(P) is the high-voltage shunt function, and R c2 (P) represents the second contact resistance under pressure P.

[0046] Specifically, the medium-pressure conductivity weighting function f(P) characterizes the degree to which the second conductive layer gradually participates in current transmission as the pressure increases, while the high-pressure shunt function g(P) characterizes the intensity of the shunt effect generated after the second conductive layer forms a parallel conductive path.

[0047] The following can be compiled: ; Where n is the number of second micro-viewpoints.

[0048] As shown in the above equation, the influence of the resistance matching coefficient λ is relatively weak in the low-pressure and medium-pressure stages. However, in the high-pressure stage, as g(P) gradually increases, the parallel shunting effect generated by the second conductive layer strengthens, and at this time, the resistance matching coefficient λ directly affects the rate of change of resistance with pressure. Therefore, the linearity of the overall response curve of the heterogeneous conductive fabric pressure sensor mainly depends on the degree of compensation for the nonlinearity of the early response caused by the shunting effect in the high-pressure stage.

[0049] S22. Based on the macroscopic equivalent resistance expression obtained in S21, the evolution law of current transmission and shunting of the heterogeneous conductive fabric pressure sensor in different pressure ranges is analyzed, and the equivalent resistance ratio expression is obtained.

[0050] To ensure that the resistance change caused by pressure variation is as linear as possible, the resistance matching coefficient λ should satisfy the following in the target response: ; Where a is the first constant and b is the second constant.

[0051] This requires that the first derivative of the actual response curve with respect to pressure remain as constant as possible, i.e.: ; Furthermore, to reduce the curvature of the response curve, the second derivative of the pressure response curve can be made to approach zero: ; Taking the second derivative of R(P,λ) with respect to the external pressure P, we get: ; in, ; Wherein, ΔR(λ) represents the equivalent shunt resistance reduction generated by a single contact point.

[0052] Therefore, the equivalent current shunt resistance reduction ΔR(λ) generated by a single contact point can be changed by adjusting the resistance matching coefficient λ, so that the current shunt resistance reduction effect in the high-pressure stage compensates for the nonlinear changes generated in the low-pressure and medium-pressure stages. The pressure response curve of the heterogeneous conductive fabric pressure sensor is closest to linear when the following equation is satisfied: ; Furthermore, due to: ; Therefore, the optimal resistance matching coefficient should satisfy: ; Where λopt is the optimal resistance matching coefficient. For the first nonlinearity, For the second nonlinearity, This is the shunt enhancement rate during the high-voltage phase.

[0053] Specifically, the first nonlinearity characterizes the degree of nonlinearity of the contact resistance between the first conductive layer and the electrode as a function of pressure, while the second linearity characterizes the degree of nonlinearity of the interlayer contact conduction process as a function of pressure.

[0054] S3. Based on the equivalent resistance ratio formula of S2, determine the optimal resistance ratio range. Combined with wide-range pressure loading test, determine the target resistance ratio that enables the linearity of the heterogeneous conductive fabric pressure sensor to be achieved.

[0055] S31. Based on the macroscopic equivalent resistance ratio expression of S2, determine the range of resistance ratios between the first and second conductive layers that enables the linearity of the heterogeneous conductive fabric pressure sensor: Considering fabric structure fluctuations, interlayer contact resistance variations, and testing errors, the target resistivity is not a single value, but rather a range centered on λopt: ; ; ; Right now , ; Where k1 is the first resistor matching tolerance coefficient and k2 is the second resistor matching tolerance coefficient.

[0056] Therefore, when the above formula is satisfied, the heterogeneous conductive fabric pressure sensor can obtain a better wide-range linear response.

[0057] S32. Based on the resistance ratio range between the first conductive layer and the second conductive layer determined in S31, a wide-range pressure loading test is performed to determine the target resistance ratio that enables the linearity of the heterogeneous conductive fabric pressure sensor to be achieved.

[0058] Wide-range pressure loading performance tests have verified that when the volume resistance ratio of the first conductive layer to the second conductive layer is in the range of 60 to 80, the overall performance of the heterogeneous conductive fabric pressure sensor is excellent; when the volume resistance ratio of the first conductive layer to the second conductive layer is 78, the overall performance of the device reaches the optimal level.

[0059] Specifically, by preparing multiple MXene solutions of different concentrations, multiple conductive layers with different resistances are obtained. The fabric base layer, conductive layer and top protective layer are stacked in sequence and the edges are encapsulated and fixed to obtain a single-layer fabric pressure sensor test sample. The linearity of the single-layer fabric pressure sensor is then tested to obtain the test results.

[0060] Specifically, in a preferred embodiment, the linearity test results of the single-layer fabric pressure sensor are as follows: Figure 8 As shown, the colloidal solution concentrations were 5 mg / mL, 2.5 mg / mL, 1.67 mg / mL, 1.25 mg / mL, 1 mg / mL, and 0.83 mg / mL, respectively. The corresponding bulk resistance values ​​of the conductive layer were 33, 255, 596, 1751, 2574, and 6373 Ω / sq, and were labeled #1 to #6. These six single-layer fabric pressure sensors are named OL-1 to OL-6. The test results show that the single-layer fabric pressure sensor exhibits high sensitivity in the low-pressure loading range; however, when the applied pressure exceeds approximately 200 kPa, the current change amplitude decreases significantly, and the response curve tends to flatten, indicating that the pressure at this point is close to the upper limit of the sensing range of the single-layer fabric pressure sensor.

[0061] Two conductive layers with different resistances are selected and combined. The layer with the higher volume resistance is used as the first conductive layer, and the layer with the lower volume resistance is used as the second conductive layer. The layers are encapsulated and fixed using a fabric base layer and a top protective layer to obtain a test sample of the heterogeneous conductive fabric pressure sensor. The linearity of the heterogeneous conductive fabric pressure sensor is then tested to obtain the test results.

[0062] Specifically, in a preferred embodiment, the linearity test results of the heterogeneous conductive fabric pressure sensor are as follows: Figure 9 As shown in the diagram, in this structure, a #1 conductive cotton fabric with low sheet resistance is used as the fixed second conductive layer. The first conductive layer is composed of #1 to #6 conductive cotton fabrics, thus obtaining a heterogeneous conductive fabric pressure sensor, named TL-1 to TL-6. Sensitivity and linearity tests were conducted on the above six heterogeneous fabric pressure sensors. The results show that, compared with the single-layer fabric pressure sensor structure, the heterogeneous conductive fabric pressure sensor exhibits superior linear response characteristics in a higher pressure range, and its linear range can be extended to approximately 400 kPa. Further analysis shows that as the sheet resistance of the first conductive layer increases, the overall sensitivity of the heterogeneous conductive fabric pressure sensor gradually increases. However, when the first conductive layer uses the #6 conductive cotton fabric with the highest sheet resistance, although it has high sensitivity in the low-to-medium pressure range, a significant response saturation phenomenon occurs after the pressure exceeds 400 kPa. In contrast, when the first conductive layer uses the #5 conductive cotton fabric, the heterogeneous fabric pressure sensor can still maintain good linear response characteristics in a pressure range as high as 600 kPa.

[0063] Furthermore, such as Figure 10 As shown, the linearity of twelve sensors, from OL-1 to OL-6 and TL-1 to TL-6, within a pressure range of 600 kPa was systematically compared. The results show that the heterogeneous conductive fabric pressure sensor significantly outperforms the single-layer conductive sensing layer structure in terms of overall linearity. The resistivity ratios of TL-1 to TL-6 are 1, 7.7, 18.1, 53.1, 78, and 193.1, respectively. Among them, sensor TL-5... At a sensitivity of 78, it exhibits a linearity of up to 99.76% while maintaining high sensitivity, making it the best overall performer.

[0064] like Figure 11 As shown, the linearity is 99.76% and the sensitivity is 3.41 kPa⁻¹ in the range of 0-600 kPa; the corresponding sensitivity is 0.41 kPa⁻¹ and the linearity is 83.4% in the range of 600-1100 kPa.

[0065] like Figure 12As shown, the response time and recovery time at a pressure of approximately 132 kPa are 40 ms and 80 ms, respectively.

[0066] like Figure 13 As shown, under load conditions of fixed pressure and varying frequency, the sensor output signal remains stable.

[0067] like Figure 14 As shown, hydrophobicity tests were conducted on the fabric base layer and top protective layer. First, the water contact angle (WCA) of the polyester fabrics treated with HDTMS (HF) and SA (SF) was measured. The untreated polyester fabric (NF) exhibited hydrophilicity, while its hydrophobicity was significantly improved after single HDTMS or SA treatment, with contact angles reaching approximately 130°. However, after a two-step chemical blending treatment (HSF), the contact angle reached 165°, exhibiting superior superhydrophobicity. Dynamic contact experiments between water droplets and the fabric surface were also conducted. The results showed that water droplets hardly adhered to the fabric during dynamic contact, demonstrating hydrophobicity.

[0068] like Figure 15 As shown, in practical applications, the surface of a pressure sensor made of heterogeneous conductive fabric may encounter interference from other types of liquids. Based on this consideration, the contact angles between the fabric and eight common liquids (acid solution, alkaline solution, salt solution, fruit juice, coffee, milk, tea, and milk tea) were tested. The test results show that the polyester fabric surface treated with a two-step chemical process exhibits excellent hydrophobicity to common everyday liquids.

[0069] like Figure 16 As shown, the stable hydrophobicity of the fabric surface is crucial for its daily applications. Therefore, the robustness of its surface hydrophobicity was tested. Since the fabricated sensor is a pressure sensor, the surface hydrophobicity was first tested under cyclic pressure conditions. Contact angle tests were conducted by applying a pressure of 200 kPa at 5000-cycle intervals. After 25,000 cycles, the water contact angle on the fabric surface remained at 155°, maintaining a stable superhydrophobicity greater than 150°. Even after bending and twisting, water droplets remained stably suspended on the fabric surface, further confirming its hydrophobic stability. In addition, the contact angle of the fabric surface under cyclic friction conditions was tested. The specific test procedure was as follows: a 50-gram weight was placed on the fabric surface, which was then placed on 1000-grit sandpaper. Each cycle consisted of a 10-centimeter reciprocating rubbing distance, and the contact angle was tested after multiple cycles. The results showed that after 120 cycles, the contact angle on the fabric surface remained at 140°, indicating that its hydrophobicity remained good.

[0070] like Figure 17As shown, the sensor maintains a relatively stable response to this dynamic pressure. The long-term stability of the sensor is crucial for practical applications. Therefore, the sensor underwent approximately 7000 cycle tests, demonstrating its stability even under long-term cyclic conditions (~400 kPa).

[0071] like Figure 18 The diagram illustrates the mobile data acquisition interface and signal acquisition circuit structure. The system includes a voltage divider circuit, a main control chip, and a Bluetooth module. Sensor signals are transmitted via Bluetooth and displayed on the mobile terminal.

[0072] like Figure 19 As shown, the sensor was fixed to the finger joint, and its signal was tested under continuous bending at different angles. The test results show that the prepared sensor can distinguish different bending angles of the finger. In practical applications, the sensor can be fixed or attached to different parts of the human body to monitor bending movements of joints including but not limited to fingers, wrists, elbows, and legs, as well as large-amplitude human movements such as squatting.

[0073] S4. Based on the heterogeneous conductive fabric pressure sensor structure determined in S1, and combined with the target resistance ratio determined in S3, the heterogeneous conductive fabric pressure sensor is prepared and assembled.

[0074] Specifically, by adjusting the impregnation concentration of the colloidal solution, a first conductive layer and a second conductive layer with different bulk resistance combinations are prepared, and then assembled to obtain a heterogeneous conductive fabric pressure sensor.

[0075] Specifically, a low-concentration MXene solution is used to treat the first conductive layer, and a high-concentration MXene solution is used to treat the second conductive layer, so that the first conductive layer has a higher resistance than the second conductive layer.

[0076] The complete fabrication process of the heterogeneous conductive fabric pressure sensor is as follows: Figure 5 As shown.

[0077] S41. A two-step chemical method is used to treat the fabric base layer and top protective layer with hydrophobicity, so that the fabric base layer and top protective layer are hydrophobic.

[0078] Specifically, the two-step chemical method involves sequentially immersing the fabric's base layer and top protective layer in an ethanol solution of HDTMS and a hot water emulsion of SA, followed by drying. This treatment with these two low surface energy materials imparts superior hydrophobicity to the fabric.

[0079] S42. Using screen printing, the interdigitated electrode template prepared by laser processing is printed onto the surface of the fabric substrate layer, thereby obtaining a fabric substrate layer with interdigitated electrodes.

[0080] Specifically, the interdigitated electrode template is prepared by laser processing, and silver paste is printed onto the surface of the fabric substrate layer by screen printing. After heating and curing, the interdigitated electrodes are formed, thus obtaining a fabric substrate layer with interdigitated electrodes.

[0081] S43. The first conductive layer and the second conductive layer are immersed in colloidal solutions of different concentrations and then dried to obtain first conductive layers and second conductive layers with different bulk resistances.

[0082] The thickness of the MXene thin layer as measured by atomic force microscopy is as follows Figure 6 As shown.

[0083] like Figure 7 As shown, the adhesion of MXene to the fabric surface was confirmed by Tyndall effect and EDS analysis.

[0084] S44. Based on the main structure of the heterogeneous conductive fabric pressure sensor determined in S1, the prepared fabric base layer, first conductive layer, second conductive layer and top protective layer are stacked in sequence, and the edges are sealed and fixed to obtain the heterogeneous conductive fabric pressure sensor.

[0085] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor, characterized in that: It includes: S1. The multi-layer fiber stacked structure is determined as the main structure of the heterogeneous conductive fabric pressure sensor. Its structure, from bottom to top, includes: fabric base layer, first conductive layer, second conductive layer and top protective layer; the fabric base layer is provided with interdigitated electrodes for signal acquisition and transmission. S2. Conduct pressure sensing mechanism analysis and construct an equivalent resistance ratio model based on a multi-level heterogeneous conductive network; S21. Analyze the current transmission path of the heterogeneous conductive fabric pressure sensor under different pressure stages, and construct a macroscopic equivalent resistance expression that can reflect the resistance change law. ； Among them, R macro (P) represents the macroscopic equivalent resistance under pressure P; P is the external pressure; R c1 (P) represents the first contact resistance under pressure P; R m R is the first microscopic resistance; m is the number of first microscopic points; c2 (P) represents the second contact resistance under pressure P; f(P) is the medium-pressure conductivity weighting function; g(P) is the high-pressure shunt function; n is the number of second micro-points; λ is the resistance matching coefficient; S22. Based on the macroscopic equivalent resistance expression obtained in S21, the evolution law of current transmission and shunting of the heterogeneous conductive fabric pressure sensor in different pressure ranges is analyzed to obtain the equivalent resistance ratio expression. ； Where λopt is the optimal resistance matching coefficient; For the first nonlinearity, For the second nonlinearity, This is the shunt enhancement rate during the high-voltage phase; S3. Based on the equivalent resistance ratio formula of S2, determine the optimal resistance ratio range, and combine it with the wide-range pressure loading test to determine the target resistance ratio that can make the linearity of the heterogeneous conductive fabric pressure sensor reach. S4. Based on the heterogeneous conductive fabric pressure sensor structure determined in S1, and combined with the target resistance ratio determined in S3, the heterogeneous conductive fabric pressure sensor is prepared and assembled.

2. The method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor according to claim 1, characterized in that: Step S21 includes: S211. Analyze the resistance of the heterogeneous conductive fabric pressure sensor under low pressure to obtain the low-pressure resistance of the heterogeneous conductive fabric pressure sensor. S212. Analyze the resistance of the heterogeneous conductive fabric pressure sensor under medium pressure to obtain the medium pressure resistance of the heterogeneous conductive fabric pressure sensor. S213. Analyze the resistance of the heterogeneous conductive fabric pressure sensor under high pressure to obtain the macroscopic high pressure resistance of the heterogeneous conductive fabric pressure sensor. S214, combined with the low-voltage resistor obtained from S211, the medium-voltage resistor obtained from S212, and the macroscopic high-voltage resistor obtained from S213, yields the macroscopic equivalent resistance of the heterogeneous conductive fabric pressure sensor.

3. The method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor according to claim 2, characterized in that: Low-voltage resistance R of heterogeneous conductive fabric pressure sensor 低 for: Among them, R HB R is the bulk resistance of the first conductive layer. c1 The first contact resistance; Medium pressure resistance R of heterogeneous conductive fabric pressure sensor 中 for: =2 + + ； in, This is the second contact resistance.

4. The method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor according to claim 3, characterized in that: Step S213 includes: S2131. Analyze the resistance of the micro-viewpoint positioning of the heterogeneous conductive fabric pressure sensor under high pressure to obtain the high-voltage resistance R of the micro-viewpoint positioning of the heterogeneous conductive fabric pressure sensor. eq : ； S2132. Based on the current shunting mechanism and combined with the micro-view high-voltage resistor obtained in S2131, the macroscopic resistance of the heterogeneous conductive fabric pressure sensor under high voltage is analyzed to obtain the macroscopic high-voltage resistance of the heterogeneous conductive fabric pressure sensor.

5. The method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor according to claim 4, characterized in that: Step S3 specifically includes: S31. Based on the macroscopic equivalent resistance ratio expression of S2, determine the range of resistance ratios between the first and second conductive layers that enables the linearity of the heterogeneous conductive fabric pressure sensor: ， ； Where k1 is the first resistor matching tolerance coefficient and k2 is the second resistor matching tolerance coefficient; S32. Based on the resistance ratio range between the first conductive layer and the second conductive layer determined in S31, a wide-range pressure loading test is performed to determine the target resistance ratio that enables the linearity of the heterogeneous conductive fabric pressure sensor to be achieved.

6. The method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor according to claim 5, characterized in that: Step S4 includes: S41. A two-step chemical method is used to hydrophobically treat the fabric base layer and top protective layer to make the fabric base layer and top protective layer hydrophobic. S42. Using screen printing, the interdigitated electrode template prepared by laser processing is printed onto the surface of the fabric substrate layer to obtain a fabric substrate layer with interdigitated electrodes. S43. The first conductive layer and the second conductive layer are immersed in colloidal solutions of different concentrations and then dried to obtain first conductive layers and second conductive layers with different bulk resistances. S44. Based on the main structure of the heterogeneous conductive fabric pressure sensor determined in S1, the prepared fabric base layer, first conductive layer, second conductive layer and top protective layer are stacked in sequence, and the edges are sealed and fixed to obtain the heterogeneous conductive fabric pressure sensor.

7. The method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor according to claim 6, characterized in that: The volume resistance ratio between the first conductive layer and the second conductive layer is in the range of 60 to 80.

8. The method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor according to claim 7, characterized in that: When the contact between the first conductive layer and the fabric substrate electrode approaches saturation, and the shunting of the second conductive layer is enhanced, the linearity of the heterogeneous conductive fabric pressure sensor reaches its optimal level.

9. The method for fabricating a wide-range adaptive heterogeneous conductive fabric pressure sensor according to claim 4, characterized in that: The macroscopic high-voltage resistor value R(P) in step S2132 is: ； Where x(P) represents the number of the first and second effective conductive contact points under pressure P.

10. A heterogeneous conductive fabric pressure sensor prepared by the method for preparing a wide-range adaptive heterogeneous conductive fabric pressure sensor according to any one of claims 1-9, characterized in that: Its main structure is a multi-layer fiber stacked structure, which includes, from bottom to top: a fabric base layer, a first conductive layer, a second conductive layer and a top protective layer; the fabric base layer is provided with interdigitated electrodes for signal acquisition and transmission; wherein, the fabric base layer is a superhydrophobic polyester base layer, the first conductive layer is a high sheet resistance conductive cotton fabric layer, the second conductive layer is a low sheet resistance conductive cotton fabric layer, and the top protective layer is a superhydrophobic polyester protective layer.

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