A flexible pressure sensor with an array crack structure and its preparation method

Abstract

The present invention relates to the technical field of flexible pressure sensors, and provides an array crack structure flexible pressure sensor and a preparation method thereof. The preparation method includes: decomposing the target performance requirements into constraint conditions of laser processing parameters and crack structure parameters; searching for feasible solutions of laser processing parameters and crack structure parameters that meet the constraint conditions, and outputting all parameter combinations; generating a first array structure design drawing, and preparing a flexible pressure sensor based on the laser processing parameters and the first array structure design drawing to obtain a first flexible pressure sensor; judging whether the performance of the first flexible pressure sensor meets the target performance requirements. If not, a second parameter combination is generated based on the performance difference, the correlation constraint between parameters, and the irreversibility of the first parameter combination; generating a second array structure design drawing, and processing the first flexible pressure sensor based on the laser processing parameters in the second parameter combination and the second array structure design drawing to obtain a second flexible pressure sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible pressure sensors, in particular to an array crack structure flexible pressure sensor and a preparation method thereof. Background Art

[0002] In the field of flexible pressure sensors, although certain progress has been made in the prior art, there are still many problems to be solved urgently. Currently, common flexible pressure sensors have problems such as limited sensitivity, low resolution, and poor linearity in the high-pressure range, making it difficult to have both high sensitivity and a wide pressure range, which limits the application of flexible pressure sensors in multiple fields. Moreover, the preparation methods of flexible pressure sensors mostly focus on the optimization of single performance, and only focus on improving sensitivity or expanding the linear range, but ignore the mutual connection and balance between them. This results in that in practical applications, the sensor may perform well in a certain performance index, but is not satisfactory in other key performances, and it is difficult to meet the complex and changeable measurement requirements.

[0003] Even more, the traditional preparation process cannot accurately control the laser processing parameters and crack structure parameters. Minor fluctuations in the laser processing energy and speed may significantly affect the sensor performance, and it is also difficult to achieve high-precision regulation of key structure parameters such as the crack period length, number of cracks, and distribution gradient coefficient. This inaccuracy directly leads to unstable product quality, large performance differences among sensors in the same batch, and seriously affects the reliability and consistency of the products.

[0004] When the sensor performance does not meet the expectations, the prior art lacks effective parameter adjustment strategies: on the one hand, the correlation constraints between parameters are complex, and adjusting one parameter may trigger a chain reaction and affect other performance indexes; on the other hand, some processing steps in the traditional preparation process are irreversible. Once an error occurs, the entire product may be scrapped, which not only wastes a large amount of raw materials, but also increases the production cost and time cost. Summary of the Invention

[0005] Aiming at the above defects, the purpose of the present invention is to provide an array crack structure flexible pressure sensor and a preparation method thereof, aiming to solve the problems of insufficient sensitivity, resolution, and linearity of existing flexible pressure sensors in the high-pressure range, and to accurately obtain manufacturing parameters according to the target performance requirements during the sensor preparation process, so as to manufacture sensors that meet the requirements. By iteratively optimizing the laser processing parameters and crack structure parameters, accurate regulation of the sensor performance is realized, the flexibility and success rate of the preparation process are improved, and the preparation cost is reduced.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] An array crack structure flexible pressure sensor, comprising: a dielectric layer and an electrode layer arranged in sequence from top to bottom;

[0008] One side of the dielectric layer that is in close contact with the electrode layer is a periodically cracked structure surface obtained by laser marking processing, and the opposite side of the dielectric layer to the periodically cracked structure surface is a smooth and flat pressure-receiving surface for receiving an external load;

[0009] When subjected to a load, the periodically cracked structure surface will deform, increasing the contact area between the dielectric layer and the electrode layer, thereby increasing the number of current paths on the surface of the dielectric layer, reducing the surface resistance of the dielectric layer, and thus increasing the current.

[0010] Preferably, the area of the periodically cracked structure surface of the dielectric layer is , and the thickness of the dielectric layer is 500 .

[0011] Preferably, on the periodically cracked structure surface of the dielectric layer, both the x-axis direction and the y-axis direction are periodically distributed, and the cracks in the x-axis direction intersect perpendicularly with the cracks in the y-axis direction. The cross-section of the crack is bell-shaped, the long axis of the crack shape is perpendicular to the surface where the dielectric layer contacts the electrode layer, and the short axis of the crack shape is parallel to the surface where the dielectric layer contacts the electrode layer.

[0012] Preferably, the electrode layer is an FCP interdigital electrode layer.

[0013] A preparation method for an array cracked structure flexible pressure sensor, which is applied to the array cracked structure flexible pressure sensor as described above, and the preparation method includes the following steps:

[0014] S1: Obtain the target performance requirements of the flexible pressure sensor, and the target performance requirements include sensitivity, linear range, and spatial resolution;

[0015] S2: Decompose the target performance requirements into constraint conditions of laser processing parameters and cracked structure parameters, where the laser processing parameters include processing energy and processing speed, and the cracked structure parameters include crack period length, crack period number, and crack period distribution gradient coefficient;

[0016] S3: Based on the active regression algorithm, iteratively search for all feasible solutions of laser processing parameters and cracked structure parameters that meet the constraint conditions, and output all parameter combinations of the target performance requirements;

[0017] S4: Obtain a first parameter combination from all parameter combinations, generate a first array structure design drawing according to the cracked structure parameters in the first parameter combination, and prepare the flexible pressure sensor based on the laser processing parameters in the first parameter combination and the first array structure design drawing to obtain a first flexible pressure sensor;

[0018] S5: Perform performance testing on the first flexible pressure sensor to determine whether the performance of the first flexible pressure sensor meets the target performance requirements. If so, complete the preparation of the sensor;

[0019] If not, generate a second parameter combination based on the performance difference, the correlation constraints between parameters, and the irreversible parameters in the first parameter combination, and execute step S6;

[0020] S6: Generate a second array structure design diagram according to the crack structure parameters in the second parameter combination, and process the first flexible pressure sensor based on the laser processing parameters and the second array structure design diagram in the second parameter combination to obtain a second flexible pressure sensor.

[0021] Preferably, the decomposition of the target performance requirements into the constraint conditions of the laser processing parameters and the crack structure parameters includes:

[0022] Map the sensitivity to the upper limit constraint of the crack period length and the lower limit constraint of the number of crack periods. The sensitivity is negatively correlated with the crack period length and positively correlated with the number of crack periods;

[0023] Map the linear range to the direction constraint of the crack period distribution gradient coefficient. The positive gradient coefficient is used to expand the high-pressure detection range of the sensor, and the negative gradient coefficient is used to improve the low-pressure sensitivity of the sensor;

[0024] Map the spatial resolution to the lower limit constraint of the crack period length and the upper limit constraint of the number of crack periods;

[0025] Define the lower limit constraint of the processing energy and the upper limit constraint of the processing speed according to the material tolerance and the laser equipment capacity.

[0026] Preferably, iteratively search for all feasible solutions of the laser processing parameters and the crack structure parameters that meet the constraint conditions based on the active regression algorithm, and output all parameter combinations of the target performance requirements, including:

[0027] Generate an initial parameter combination set through Latin hypercube sampling to cover the parameter space of the processing energy, processing speed, crack period length, number, and gradient coefficient;

[0028] Use the Gaussian process regression model to establish a non-linear mapping relationship between parameters and performance, and predict the performance indicators of the candidate parameter combinations;

[0029] Select the next candidate parameter combination based on the expected improvement criterion, preferentially explore the region where the predicted performance is better than the current optimal solution, iteratively update the Gaussian process regression model and screen the feasible solutions until the performance tolerance is met or the maximum number of iterations is reached;

[0030] Output all parameter combinations that meet the constraint conditions and their performance prediction values.

[0031] Preferably, step S5 includes:

[0032] Obtain the measured performance data of the first flexible pressure sensor and calculate the deviation value between it and the target performance requirement;

[0033] Determine the laser processing parameters and / or crack structure parameters to be adjusted according to the deviation value;

[0034] Based on the associated constraint conditions between parameters, verify the feasibility of the second parameter combination: verify whether the laser processing parameters in the second parameter combination exceed the equipment process limit, verify whether the crack period length and number in the second parameter combination meet the minimum crack spacing constraint, and verify whether the gradient coefficient in the second parameter combination exceeds the deformation tolerance range of the material;

[0035] If there are irreversible parameter modifications, lock the irreversible parameters and preferentially adjust other associated parameters;

[0036] Dynamically adjust the parameter combination according to the priority: preferentially adjust the gradient coefficient of the crack period distribution to adapt to the change in the number of periods, secondly adjust the crack period length to maintain the crack spacing constraint, and finally adjust the laser processing speed;

[0037] Generate the second parameter combination and output the adjusted performance prediction value.

[0038] Preferably, based on the laser processing parameters in the first parameter combination and the first array structure design drawing, prepare the flexible pressure sensor, and the obtained first flexible pressure sensor includes:

[0039] Cut the conductive silicone according to the preset size, put the cut conductive silicone into anhydrous ethanol for soaking and perform ultrasonic treatment;

[0040] Cut out the interdigital electrodes and weld them to the conductive silicone;

[0041] According to the first array structure design drawing, use a laser to mark an array of crack structures on the surface of the conductive silicone. After the laser marking is completed, put it into anhydrous ethanol for soaking again and perform ultrasonic treatment to obtain the first flexible pressure sensor.

[0042] Preferably, after step S6, it further includes encapsulating the second flexible pressure sensor with hot melt adhesive or sewing thread;

[0043] When using hot melt adhesive for encapsulation, obtain flexible fabric and sheet hot melt adhesive according to the size of the second flexible pressure sensor;

[0044] Use the cut hollow sheet hot melt adhesive to stack on the interdigital electrodes, and use a hot press to hot press at 120 degrees Celsius for 20 seconds to obtain the final flexible pressure sensor.

[0045] One of the above technical solutions has the following advantages or beneficial effects:

[0046] By obtaining the target performance requirements and decomposing them into the constraint conditions of laser processing parameters and crack structure parameters, the preparation process of the present invention has a clear design orientation, can take into account multiple performance indicators such as sensitivity, linear range, and spatial resolution at the same time, and avoid the performance imbalance problem caused by the traditional method only focusing on the optimization of a single performance; based on the active regression algorithm to iteratively search for the parameter combination that meets the constraint conditions, effectively solve the problem of inaccurate control of laser processing parameters and crack structure parameters in the traditional preparation process, can significantly improve the stability and consistency of product quality, and reduce the performance difference of sensors in the same batch; performing performance tests on the first flexible pressure sensor and generating the second parameter combination according to the performance difference, and subsequent generating the second array structure design drawing according to the second parameter combination and processing, can provide an effective parameter adjustment strategy, avoid product scrapping caused by improper parameter adjustment, and effectively reduce production costs and time costs. Description of the Drawings

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0048] Figure 1 is the flowchart of the preparation method of the array crack structure flexible pressure sensor provided by the embodiment of the present invention;

[0049] Figure 2 is the structural schematic diagram of the interdigital electrode layer of the array crack structure flexible pressure sensor provided by the embodiment of the present invention;

[0050] Figure 3 is the schematic diagram of the array crack structure of the array crack structure flexible pressure sensor provided by the embodiment of the present invention when the crack period length is 1.05, the number of crack period strips is 25, and the crack period distribution gradient coefficient is 2;

[0051] Figure 4 is Figure 3 the enlarged structural schematic diagram of the partial array crack structure;

[0052] Figure 5 is the schematic diagram of the influence of the crack period distribution gradient coefficient in a single period on the array structure pattern when the number of crack period strips of the array crack structure flexible pressure sensor provided by the embodiment of the present invention is 50;

[0053] Figure 6 It is a schematic cross-sectional structure diagram of a flexible pressure sensor with an array crack structure provided by an embodiment of the present invention. Specific embodiments

[0054] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0055] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0056] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0057] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0058] A flexible pressure sensor with an array crack structure includes: a dielectric layer and an electrode layer arranged in sequence from top to bottom;

[0059] One side of the dielectric layer in contact with the electrode layer is a periodically cracked surface obtained by laser marking processing, and the opposite side of the dielectric layer to the periodically cracked surface is a smooth and flat pressure-receiving surface for receiving an external load;

[0060] When subjected to a load, the periodic crack structure surface will deform, increasing the contact area between the dielectric layer and the electrode layer. As a result, the number of current paths on the surface of the dielectric layer increases, the surface resistance of the dielectric layer decreases, and thus the current increases.

[0061] Specifically, based on the piezoresistive effect, pressure sensing is achieved through the dynamic change in the contact area between the dielectric layer and the electrode layer. The periodic crack structure surface of the dielectric layer is only partially in contact with the electrode layer without load, forming a high initial resistance (e.g., 10 ). When an external pressure is applied to the smooth pressure-receiving surface of the dielectric layer, the crack structure gradually closes due to deformation, resulting in an increase in the contact area between the dielectric layer and the electrode layer, an increase in the number of conductive paths, a decrease in surface resistance, and an enhancement of the current signal, enabling the detection and conversion of pressure signals.

[0062] Among them, a specific dielectric material can be selected, such as conductive silicone rubber, and the required periodic crack structure surface can be formed on the dielectric layer by controlling laser marking parameters (such as laser power, marking speed, etc.). Different laser parameters can produce cracks with different depths and widths, thereby affecting the sensitivity and response range of the sensor. Interdigitated electrodes with different shapes or sizes are used to improve the uniformity of the electric field distribution and the accuracy of current measurement. In addition, the performance of the sensor can be optimized by changing the relative position and contact method between the dielectric layer and the electrode layer, such as adjusting the thickness of the dielectric layer or the layout of the electrode layer.

[0063] Preferably, the area of the periodic crack structure surface of the dielectric layer is , and the thickness of the dielectric layer is 500 .

[0064] Specifically, the dielectric layer is a layer of material located above the electrode layer. The area of its periodic crack structure surface is 2.5 cm × 2.5 cm, and this area can determine the effective working area of the sensor, that is, the area range that can participate in pressure sensing and electrical signal conversion. The thickness of the dielectric layer is 500 μm. The thickness affects the mechanical and electrical properties of the dielectric layer. A thinner dielectric layer can respond to pressure changes faster, and when subjected to the same pressure, a thinner dielectric layer is more likely to deform, thus more significantly changing the contact area with the electrode layer, affecting the magnitude of the current, and at the same time reducing the overall thickness of the sensor, making it more suitable for application scenarios that require a thin and light design.

[0065] Preferably, on the periodic crack structure surface on the surface of the dielectric layer, the cracks are periodically distributed in both the x-axis direction and the y-axis direction, and the cracks in the x-axis direction intersect perpendicularly with the cracks in the y-axis direction. The cross-section of the crack is bell-shaped, and the long axis of the crack shape is perpendicular to the surface where the dielectric layer contacts the electrode layer, and the short axis of the crack shape is parallel to the surface where the dielectric layer contacts the electrode layer.

[0066] The design of periodic crack structure can significantly improve the sensitivity and performance of flexible pressure sensors. When the periodic crack structure surface on the surface of the dielectric layer is periodically distributed in both the x-axis and y-axis directions, and the cracks in the x-axis direction intersect perpendicularly with the cracks in the y-axis direction, this structure can produce multi-directional deformation when subjected to pressure. The cross-section of the crack is bell-shaped, with its long axis perpendicular to the surface where the dielectric layer and the electrode layer contact, and its short axis parallel to the surface. This geometric shape makes the crack closing process more efficient when subjected to pressure, thereby significantly increasing the contact area between the dielectric layer and the electrode layer, thereby increasing the number of current paths, reducing surface resistance, and significantly increasing the current, thereby achieving high-sensitivity detection of pressure changes.

[0067] Preferably, the electrode layer is a FCP interdigitated electrode layer.

[0068] Specifically, the finger-like structure of the interdigitated electrode forms multiple parallel current paths on the surface of the dielectric layer, making the changes in these paths more significant when subjected to pressure, thereby improving the sensitivity of the sensor. At the same time, the flexibility of the FCP interdigitated electrode layer enables it to adapt to the bending and stretching requirements of the flexible pressure sensor, ensuring the stability and reliability of the sensor in different forms.

[0069] A method for preparing a flexible pressure sensor with an array crack structure, wherein the method is applied to the flexible pressure sensor with an array crack structure as described above, such as Figure 1 As shown, in a preferred embodiment of the present invention, the preparation method comprises the following steps:

[0070] S1: Obtaining target performance requirements of the flexible pressure sensor, wherein the target performance requirements include sensitivity, linear range, and spatial resolution;

[0071] Specifically, sensitivity refers to the sensor's response to pressure changes, that is, the ratio of the output signal change to the pressure change. High sensitivity means that the sensor can detect tiny pressure changes more accurately. The linear range refers to the pressure range in which the sensor output is linearly related to the pressure. A wider linear range helps the sensor to accurately and stably measure at different pressures. Spatial resolution refers to the sensor's ability to distinguish between pressure changes at two adjacent points, which determines the sensor's ability to accurately detect the pressure location. The higher the spatial resolution, the greater the sensor's ability to perceive the details of pressure distribution.

[0072] S2: Decompose the target performance requirements into constraint conditions for laser processing parameters and crack structure parameters, where the laser processing parameters include processing energy and processing speed, and the crack structure parameters include crack period length, number of crack periods, and crack period distribution gradient coefficient;

[0073] Specifically, decomposing the target performance requirements into constraint conditions for laser processing parameters and crack structure parameters is a key step in transforming abstract performance indicators into specific processing and structural design requirements. Since the laser processing parameters directly affect geometric features such as the depth and width of the cracks, and the crack structure parameters determine the distribution law and density of the cracks, these factors jointly determine the performance of the flexible pressure sensor. By establishing the correlation between performance requirements and parameters, it can provide a clear constraint framework for subsequent parameter search and optimization.

[0074] The processing energy in the laser processing parameters refers to the amount of energy of the laser acting on the surface of the conductive silicone. It and the processing speed jointly determine the action intensity and time of the laser on the material, thereby affecting the depth and width of the cracks; the crack period length refers to the distance between two adjacent cracks along a certain direction on the surface of the dielectric layer, which determines the length of a single crack period in the x - direction and y - direction respectively, and it affects the distribution density of the cracks; the number of crack periods is the number of cracks included in one period in one direction, and it and the period length jointly determine the tightness of the crack arrangement in that direction; the crack period distribution gradient coefficient is used to describe the density change law of the crack distribution within one period range, so that the n cracks within the period are not evenly distributed, but are denser at both ends of the period range and looser in the center of the period range, thereby affecting the change characteristics of the contact area between the dielectric and the electrode.

[0075] S3: Based on the active regression algorithm, iteratively search for all feasible solutions of laser processing parameters and crack structure parameters that meet the constraint conditions, and output all parameter combinations of the target performance requirements;

[0076] The active regression algorithm is a data - driven optimization method. By continuously performing experimental sampling and model updating, it gradually approaches the parameter combinations that meet the constraint conditions. In this step S3, using the active regression algorithm to iteratively search for all feasible solutions of laser processing parameters and crack structure parameters that meet the constraint conditions can fully explore the potential optimal solutions in the parameter space, taking into account the mutual influence and correlation between parameters, and output multiple possible parameter combinations of the target performance requirements, providing rich choices for subsequent preparation and optimization.

[0077] Among them, in some embodiments, the Gaussian active regression algorithm can be adopted to model the parameter space using a Gaussian process model, and the next experimental sample point is selected by maximizing the acquisition function, gradually converging to a parameter combination that satisfies the constraint conditions; the Bayesian regression algorithm can also be used to construct the prior distribution and likelihood function of the parameters based on Bayesian statistical theory, and continuously optimize the search direction of the parameter combination through the update of the posterior distribution; other optimization algorithms can also be combined, such as genetic algorithms, particle swarm optimization algorithms, etc., to perform collaborative optimization with the active regression algorithm to improve the globality and diversity of the search.

[0078] S4: Obtain a first parameter combination from all parameter combinations, generate a first array structure design drawing according to the fracture structure parameters in the first parameter combination, and fabricate a flexible pressure sensor based on the laser processing parameters in the first parameter combination and the first array structure design drawing to obtain a first flexible pressure sensor;

[0079] Specifically, obtaining a first parameter combination from all parameter combinations and generating a first array structure design drawing according to the fracture structure parameters therein, and fabricating based on the laser processing parameters and the design drawing can transform the abstract parameter combination into a specific physical structure and processing technology, and obtain a first flexible pressure sensor through the actual fabrication process, thus realizing an important transformation from theoretical design to physical product and providing a physical basis for further performance testing and optimization.

[0080] The first parameter combination refers to a specific set of laser processing parameters and fracture structure parameters selected from among many parameter combinations that satisfy the constraint conditions, which represents a possible fabrication scheme; the first array structure design drawing is a graphic file generated using computer-aided design software based on the fracture structure parameters in the first parameter combination and is used to guide laser processing. It details information such as the distribution position, shape, and size of the fractures and is the basis for precise processing by the laser processing equipment; the first flexible pressure sensor is the first physical sensor fabricated according to the first parameter combination and the design drawing, and its performance will directly reflect the rationality of this parameter combination.

[0081] S5: Perform performance testing on the first flexible pressure sensor to determine whether the performance of the first flexible pressure sensor meets the target performance requirements. If so, the fabrication of the sensor is completed;

[0082] If not, generate a second parameter combination based on the performance difference, the correlation constraints between parameters, and the irreversible parameters in the first parameter combination, and execute step S6;

[0083] Specifically, by performing performance tests on the first flexible pressure sensor, the gap between its actual performance and the target performance requirements can be intuitively understood. By judging whether the performance meets the requirements, it is decided whether further optimization is needed. If the performance does not meet the requirements, a second parameter combination is generated based on the performance differences, the correlation constraints between parameters, and the irreversibility of some or all of the parameters in the first parameter combination. This is a feedback and correction process for the initial design scheme, aiming to gradually approach the target performance requirements by adjusting the parameter combination and improve the performance of the sensor.

[0084] Among them, performance testing refers to the actual measurement and evaluation of performance indicators such as the sensitivity, linear range, and spatial resolution of the first flexible pressure sensor using professional testing equipment and methods to obtain its true performance data; performance difference refers to the deviation degree between the measured performance data and the target performance requirements, which reflects the deficiencies in the sensor performance under the current parameter combination; the correlation constraints between parameters refer to the relationship of mutual influence and restriction between the laser processing parameters and the crack structure parameters. This relationship determines that when one parameter is adjusted, other related parameters also need to be adjusted accordingly to maintain the overall rationality of the parameter combination; the irreversibility of the parameters in the first parameter combination means that once the preparation process is completed according to the first parameter combination, due to the irreversible changes of the materials and the completion of the processing process, it is impossible to directly modify the first parameter combination. For example, it is not feasible to reduce the crack length to affect the performance. Instead, a new parameter combination can only be generated and the original crack length can be retained to optimize the performance. Thus, modifications can be made based on the first parameter combination.

[0085] S6: Generate a second array structure design drawing according to the crack structure parameters in the second parameter combination, and process the first flexible pressure sensor based on the laser processing parameters in the second parameter combination and the second array structure design drawing to obtain a second flexible pressure sensor.

[0086] Such as Figures 2 - 6 , are all related drawings of the array crack structure flexible pressure sensor made by the preparation method proposed by the present invention. Among them, Figure 6For convenience of representation, the array protrusion structure does not show the actual distribution and quantity; the second parameter combination refers to a new set of laser processing parameters and crack structure parameters adjusted on the basis of the first parameter combination according to performance differences and parameter correlation constraints, which represents the optimization and improvement direction of the initial design scheme; the second array structure design drawing is a new design drawing generated according to the crack structure parameters in the second parameter combination, and is used to guide the laser processing equipment to perform secondary processing on the first flexible pressure sensor and adjust its crack structure; processing the first flexible pressure sensor means reprocessing on the basis of the existing sensor using the laser processing equipment according to the new parameters and design drawing, and trimming or supplementing the crack structure of the dielectric layer to change the performance of the sensor.

[0087] Specifically, the second array structure design drawing is generated according to the crack structure parameters in the second parameter combination, and the first flexible pressure sensor is processed based on the new laser processing parameters and design drawing to obtain the second flexible pressure sensor. This is an optimization and improvement process of the initial preparation scheme. In this way, when the preparation effect of the sensor is not ideal, on the basis of the original preparation process and equipment, the structure and performance of the sensor can be adjusted and optimized specifically, gradually approaching the target performance requirements, improving the overall performance and stability of the sensor, and saving costs at the same time.

[0088] Preferably, the decomposition of the target performance requirements into the constraint conditions of the laser processing parameters and the crack structure parameters includes:

[0089] Mapping the sensitivity to the upper limit constraint of the crack period length and the lower limit constraint of the number of crack periods, where the sensitivity is negatively correlated with the crack period length and positively correlated with the number of crack periods;

[0090] Mapping the linear range to the direction constraint of the crack period distribution gradient coefficient, where the positive gradient coefficient is used to expand the high-voltage detection range of the sensor, and the negative gradient coefficient is used to improve the low-voltage sensitivity of the sensor;

[0091] Mapping the spatial resolution to the lower limit constraint of the crack period length and the upper limit constraint of the number of crack periods;

[0092] Defining the lower limit constraint of the processing energy and the upper limit constraint of the processing speed according to the material tolerance and the laser equipment capacity.

[0093] In one embodiment, by establishing a mathematical mapping relationship between the target performance requirements (sensitivity, linear range, spatial resolution), the laser processing parameters (processing energy p, speed v), and the crack structure parameters (period length a, number of cracks n, gradient coefficient kc), the abstract performance indicators are transformed into quantifiable physical constraint conditions. Sensitivity is negatively correlated with the crack period length a (short-period dense cracks increase the change rate of the contact area) and positively correlated with the number of crack periods n (more crack numbers enhance the micro-pressure response). Therefore, set and ; The linear range is constrained by the gradient coefficient kc direction (positive gradient coefficient kc>0 makes the cracks sparse at both ends and dense in the center within the period, preferentially closing the central cracks to expand the high-pressure detection range; negative kc<0 makes them dense at both ends and sparse in the center, preferentially closing the edge cracks to improve the low-pressure sensitivity); The spatial resolution requires the size of the smallest detectable unit, which is mapped to (lower limit of the crack period length) and (upper limit of the number of cracks) to avoid signal crosstalk caused by over-dense cracks; Material tolerance (such as the melting point of conductive silicone) and laser equipment capabilities (maximum power) limit the processing energy , to avoid insufficient crack depth caused by insufficient energy, set the processing speed , which can ensure the processing accuracy and avoid errors caused by too fast processing speed.

[0094] Exemplarily, assuming the target sensitivity is 5 , when the crack period length a is between 100 μm and 200 μm, the sensitivity of the sensor shows an obvious negative correlation with a. To meet the sensitivity requirement of 5 , the crack period length a should not exceed 160 μm (when a = 160 μm and the sensitivity is 5.2 , it is close to and slightly lower than the target value. Considering actual processing errors and other factors, setting the upper limit of a to 150 μm can more reliably ensure that the sensitivity reaches 5 ), when the number of crack periods n is between 20 and 50, the sensitivity is positively correlated with n. To achieve a sensitivity of 5 , the number of crack periods n should be at least 35 (when n = 35, the sensitivity is 5.2 ). Therefore, the sensitivity is mapped to the upper limit constraint of the crack period length (a ≤ 150 μm) and the lower limit constraint of the number of crack periods (n ≥ 35).

[0095] Meanwhile, assume the target spatial resolution is 0.5 mm. Experiments have found that when the crack period length a is less than 50 μm, the interference between adjacent cracks will cause a decrease in spatial resolution; while when a is greater than 150 μm, the distance between cracks is too large to achieve a high spatial resolution. To meet the requirement of 0.5 mm spatial resolution, the crack period length a should be not less than 70 μm (when a = 70 μm, the spatial resolution is 0.52 mm, close to and slightly higher than the target value. Considering the actual processing accuracy and measurement error, setting the lower limit of a to 70 μm can ensure that the spatial resolution is not less than 0.5 mm). Meanwhile, experiments have shown that when the number of crack periods n exceeds 60, the cracks are too dense, resulting in an increase in signal interference between electrodes and a decrease in spatial resolution; while when n is less than 30, the crack distribution is too sparse to achieve a high spatial resolution. Therefore, to achieve a spatial resolution of 0.5 mm, the number of crack periods n should not exceed 60 (when n = 60, the spatial resolution is 0.5 mm). Therefore, map the spatial resolution to the lower limit constraint of the crack period length (a ≥ 70 μm) and the upper limit constraint of the number of crack periods (n ≤ 60), and other parameters can be obtained similarly.

[0096] Preferably, based on the active regression algorithm, iteratively search for all feasible solutions of the laser processing parameters and crack structure parameters that meet the constraint conditions, and output all parameter combinations required for the target performance, including:

[0097] Generate an initial parameter combination set through Latin hypercube sampling to cover the parameter space of processing energy, processing speed, crack period length, number, and gradient coefficient;

[0098] Use the Gaussian process regression model to establish a non-linear mapping relationship between parameters and performance, and predict the performance indicators of candidate parameter combinations;

[0099] Based on the expected improvement criterion, select the next candidate parameter combination, preferentially explore the region where the predicted performance is better than the current optimal solution, iteratively update the Gaussian process regression model and screen the feasible solutions until the performance tolerance is met or the maximum number of iterations is reached;

[0100] Output all parameter combinations that meet the constraint conditions and their performance prediction values.

[0101] Specifically, the initial parameter combination set is generated by Latin hypercube sampling, which can evenly and efficiently cover the multi-dimensional parameter space composed of processing energy, processing speed, crack cycle length, number, and gradient coefficient, providing rich initial samples for subsequent performance prediction and parameter optimization. The Gaussian process regression model is used to establish the non-linear mapping relationship between parameters and performance, which can capture the complex influence of parameter changes on performance indicators, thus accurately predicting the performance of candidate parameter combinations. The next candidate parameter combination is selected based on the expected improvement criterion, which preferentially explores the regions where the predicted performance is better than the current optimal solution, achieving a balance between global search and local optimization, and gradually approaching the parameter combination that meets the target performance requirements. The Gaussian process regression model is iteratively updated and feasible solutions are screened until the performance tolerance is met or the maximum number of iterations is reached, ensuring the continuous improvement and convergence of the search process. Finally, all parameter combinations that meet the constraint conditions and their performance prediction values are output, providing a comprehensive parameter selection for the preparation of flexible pressure sensors.

[0102] Among them, Latin hypercube sampling is a statistical sampling method that can evenly select sample points in the parameter space, avoiding the over-concentration or sparsity of sampling points. The generated initial parameter combination set is used to cover the multi-dimensional parameter space, ensuring the representativeness and diversity of the initial samples. The Gaussian process regression model is a probability-based non-linear regression method that can predict the performance indicators corresponding to any parameter combination by learning the mapping relationship between parameters and performance, providing a basis for subsequent parameter selection. The expected improvement criterion is a standard for measuring the potential improvement value of candidate parameter combinations, used to select the parameter combination that is most likely to bring performance improvement for actual testing, preferentially exploring the regions where the predicted performance is better than the current optimal solution, and guiding the search direction.

[0103] Exemplarily, when developing a flexible pressure sensor with high sensitivity, wide linear range, and high spatial resolution, the target performance requirement is sensitivity ≥ 5 , with a linear range of 0 - 100 kPa, a linearity of R² ≥ 0.95, and a spatial resolution of ≤ 0.5 mm. The team first mapped the performance indicators to the constraint conditions of laser processing parameters and crack structure parameters. For example, the sensitivity corresponded to a crack period length of ≤ 150 μm and the number of periods ≥ 35, etc. Then, 20 initial parameter combinations were generated through Latin hypercube sampling, covering parameter ranges such as processing energy of 15 - 25 mJ / mm² and processing speed of 50 - 80 mm / s. Next, a Gaussian process regression model was used to establish the non-linear mapping relationship between parameters and performance, predicting the performance indicators. Then, based on the expected improvement criterion, the next candidate parameter combination was selected. After 10 iterations, the model was updated and 15 groups of feasible solutions were screened out. Finally, the parameter combination that met the constraint conditions and its performance prediction value were output, and the optimal combination (p = 20 mJ / mm², v = 65 mm / s, a = 130 μm, n = 40, kc = 1.2) was selected to generate the crack structure design drawing, and the sensor was prepared and tested. The measured sensitivity was 5.3 , with a linearity of R² = 0.97 and a spatial resolution of 0.45 mm, meeting the target performance requirements.

[0104] Preferably, step S5 includes:

[0105] Obtain the measured performance data of the first flexible pressure sensor and calculate the deviation value between it and the target performance requirements;

[0106] Determine the laser processing parameters and / or crack structure parameters that need to be adjusted according to the deviation value;

[0107] Based on the correlation constraint conditions between parameters, verify the feasibility of the second parameter combination: verify whether the laser processing parameters in the second parameter combination exceed the equipment process limits, verify whether the crack period length and number in the second parameter combination meet the minimum crack spacing constraint, and verify whether the gradient coefficient in the second parameter combination exceeds the deformation tolerance range of the material;

[0108] If there are irreversible parameter modifications, lock the irreversible parameters and preferentially adjust other related parameters;

[0109] Dynamically adjust the parameter combination according to the priority: preferentially adjust the gradient coefficient of the crack period distribution to adapt to the change in the number of periods, secondly adjust the crack period length to maintain the crack spacing constraint, and finally adjust the laser processing speed;

[0110] Generate the second parameter combination and output the adjusted performance prediction value.

[0111] Specifically, by comparing and analyzing the measured performance data of the first flexible pressure sensor with the target performance requirements, the parameters to be adjusted are determined and a new parameter combination is generated to gradually approach the target performance. First, by calculating the deviation value between the measured performance and the target performance, the deficiencies of the current sensor performance are clarified. Then, according to the magnitude and direction of the deviation value, the laser processing parameters and / or the crack structure parameters to be adjusted are determined to compensate for the performance deviation. Next, based on the correlation constraint conditions between the parameters, the feasibility of the newly generated second parameter combination is verified to ensure that all parameters are within a reasonable range and are compatible with each other. If there are irreversible parameter modifications, these parameters are locked and other related parameters are preferentially adjusted to avoid ineffective or destructive adjustments. Finally, according to the preset priority, the parameter combination is dynamically adjusted. The crack period distribution gradient coefficient is preferentially adjusted to adapt to the change in the number of periods, followed by adjusting the crack period length to maintain the crack spacing constraint, and finally adjusting the laser processing speed to generate the second parameter combination and output the adjusted performance prediction value.

[0112] The deviation value is the difference between the measured performance data and the target performance requirements. It quantifies the degree of deficiency in the sensor performance and guides the direction and amplitude of the parameters to be adjusted. The laser processing parameters include processing energy and processing speed, which directly affect the depth and width of the cracks and thus affect the performance of the sensor. Adjusting these parameters can change the geometric characteristics of the cracks. The crack structure parameters include crack period length, crack period number, and crack period distribution gradient coefficient. These parameters determine the distribution law and density of the cracks and have a direct impact on the performance of the sensor. By adjusting them, the response characteristics of the sensor can be optimized. The correlation constraint conditions refer to the relationship of mutual influence and restriction between parameters, such as the minimum spacing constraint between the crack period length and the number, and the limitation of the gradient coefficient and the material deformation tolerance range. These conditions ensure the feasibility of the parameter combination. Irreversible parameter modification means that some parameters cannot be easily changed once set, such as the characteristics of the material itself or the fixed parameters of the processing equipment. After locking these parameters, other related parameters need to be preferentially adjusted to optimize the performance. The priority dynamic adjustment is to sort the parameter adjustment order according to the importance of the parameters to the performance and the difficulty of adjustment to ensure the efficiency and effectiveness of the adjustment process. Finally, the second parameter combination is generated and the adjusted performance prediction value is output.

[0113] Exemplarily, a performance test is carried out on the first flexible pressure sensor, and the measured sensitivity is 4.5 , the linearity R² = 0.93, and the spatial resolution is 0.6 mm. Compared with the target performance (sensitivity 5 , linear range 0 - 100 kPa and R² ≥ 0.95, spatial resolution 0.5 mm), the sensitivity deviation is calculated to be -0.5 , the linearity deviation is -0.02 and the spatial resolution deviation is +0.1 mm. Based on these deviation values and combined with the correlation model between performance and parameters, it is determined that the number of crack cycles needs to be increased by 5 to improve sensitivity, the crack cycle length needs to be reduced by 10 μm to improve spatial resolution, and the gradient coefficient of crack cycle distribution needs to be adjusted to +0.3 to improve linearity, while keeping the laser processing energy and speed within the constraint range. Then, verify the feasibility of the second parameter combination, check whether the newly set laser processing parameters (processing energy 20 mJ / mm², speed 65 mm / s) exceed the equipment process limits (processing energy 15 - 25 mJ / mm², speed 50 - 80 mm / s), confirm whether the crack cycle length of 120 μm and the number of 45 meet the minimum spacing constraint of 10 μm (calculate the adjacent crack spacing as 120 μm / 45 ≈ 2.67 μm, meeting the requirement), and verify whether the gradient coefficient of +0.3 is within the material deformation tolerance range (-2 to +2). Subsequently, it is found that the laser processing speed in the original parameter combination cannot be irreversibly increased, so the speed is locked at 65 mm / s, and the gradient coefficient of crack cycle distribution is preferentially adjusted to +0.3 to adapt to the change in the number of cycles. Secondly, the crack cycle length is adjusted to 120 μm to maintain the spacing constraint, and finally, the laser processing energy is finely adjusted to 20 mJ / mm². Finally, the second parameter combination (processing energy 20 mJ / mm², speed 65 mm / s, cycle length 120 μm, number of cycles 45, gradient coefficient +0.3) is generated, and the Gaussian process regression model is used to predict the performance, and the predicted sensitivity is output as 5.2 , the linearity R² = 0.96 and the spatial resolution is 0.48 mm, making the sensor performance closer to the target requirements. Through this iterative process, each adjustment is based on actual test data and deviation analysis, gradually approaching the target performance requirements, which can avoid losses caused by machine errors or unexpected factors of the sensor during the production process.

[0114] Preferably, the flexible pressure sensor is prepared based on the laser processing parameters in the first parameter combination and the first array structure design drawing, and the obtained first flexible pressure sensor includes:

[0115] The conductive silicone is cut according to a preset size, and the cut conductive silicone is immersed in absolute ethanol and ultrasonically treated;

[0116] The interdigital electrodes are cut out and welded to the conductive silicone;

[0117] According to the first array structure design drawing, an array crack structure is marked on the surface of the conductive silicone by laser. After the laser marking is completed, it is immersed in absolute ethanol again and ultrasonically treated to obtain the first flexible pressure sensor.

[0118] Specifically, the conductive silicone is cut according to a preset size and ultrasonically treated with absolute ethanol to remove impurities and ensure surface cleanliness, such as removing residual silicone powder on the surface; then the interdigital electrodes are cut and welded to construct the electrode part of the sensor; then the array crack structure is laser-engraved according to the design drawing, and ultrasonically treated again to remove the residue, obtaining the first flexible pressure sensor.

[0119] The preset size is the size of the conductive silicone determined according to the sensor design requirements, and precise measurement is required during cutting to ensure subsequent structural matching; absolute ethanol, as a cleaning agent, can effectively remove organic impurities on the surface of the conductive silicone, and ultrasonic treatment causes the impurities to fall off through high-frequency vibration. The combination of the two ensures surface cleanliness; the interdigital electrode is the key electrode part of the sensor, and its shape and size affect the electrical performance of the sensor. After cutting, it is welded to the conductive silicone to form an electrical connection; laser engraving is to precisely process the designed array crack structure on the surface of the conductive silicone using a laser, and its accuracy and quality directly affect the sensor performance; the array crack structure is the core design to improve the sensitivity and resolution of the sensor, and its geometric parameters determine the response characteristics of the sensor; ultrasonic treatment is carried out again after laser engraving to remove the residues generated during processing and prevent affecting the contact performance between the electrode and the dielectric layer.

[0120] Preferably, after step S6, it further includes encapsulating the second flexible pressure sensor using hot melt adhesive or sewing thread;

[0121] When using hot melt adhesive for encapsulation, flexible fabric and sheet hot melt adhesive are obtained according to the size of the second flexible pressure sensor;

[0122] The cut sheet hot melt adhesive with a hollow center is stacked on the interdigital electrodes, and hot-pressed at 120 degrees Celsius for 20 seconds using a hot press to obtain the final flexible pressure sensor.

[0123] Specifically, the cut sheet hot melt adhesive with a hollow center is stacked on the interdigital electrodes, and hot-pressed at 120 degrees Celsius for 20 seconds using a hot press to melt and bond the hot melt adhesive, forming a sealed encapsulation layer. Additionally, sewing thread stitching encapsulation can also be used. Sewing thread stitching encapsulation is suitable for application scenarios that require higher flexibility and stretchability. By stitching the flexible fabric to the edge of the sensor, additional mechanical strength and protection are provided.

[0124] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0125] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A preparation method of a flexible pressure sensor with an array crack structure, the preparation method being applied to a flexible pressure sensor with an array crack structure, the flexible pressure sensor with an array crack structure comprising: A dielectric layer and an electrode layer arranged in sequence from top to bottom; One side of the dielectric layer in contact with the electrode layer is a periodically cracked structure surface obtained by laser marking processing, and the opposite side of the dielectric layer to the periodically cracked structure surface is a smooth and flat pressure-receiving surface for receiving an external load; When a load is applied, the periodically cracked structure surface will deform, increasing the contact area between the dielectric layer and the electrode layer, thereby increasing the number of current paths on the surface of the dielectric layer, reducing the surface resistance of the dielectric layer, and thus increasing the current. The electrode layer is an FCP interdigital electrode layer, and its preparation method is characterized by including the following steps: S1: Obtain the target performance requirements of the flexible pressure sensor, where the target performance requirements include sensitivity, linear range, and spatial resolution; S2: Decompose the target performance requirements into constraint conditions of laser processing parameters and crack structure parameters, where the laser processing parameters include processing energy and processing speed, and the crack structure parameters include crack period length, crack period number, and crack period distribution gradient coefficient; S3: Based on the active regression algorithm, iteratively search for all feasible solutions of laser processing parameters and crack structure parameters that meet the constraint conditions, and output all parameter combinations of the target performance requirements; S4: Obtain the first parameter combination from all parameter combinations, generate the first array structure design drawing according to the crack structure parameters in the first parameter combination, and prepare the flexible pressure sensor based on the laser processing parameters and the first array structure design drawing in the first parameter combination to obtain the first flexible pressure sensor; S5: Perform performance testing on the first flexible pressure sensor, and determine whether the performance of the first flexible pressure sensor meets the target performance requirements. If so, the preparation of the sensor is completed; If not, generate the second parameter combination based on the performance difference, the correlation constraints between parameters, and the irreversible parameters in the first parameter combination, and execute step S6; S6: Generate the second array structure design drawing according to the crack structure parameters in the second parameter combination, and process the first flexible pressure sensor based on the laser processing parameters and the second array structure design drawing in the second parameter combination to obtain the second flexible pressure sensor.

2. The preparation method according to claim 1, wherein Decomposing the target performance requirements into constraint conditions of laser processing parameters and crack structure parameters includes: Mapping the sensitivity to the upper limit constraint of the crack period length and the lower limit constraint of the crack period number, where the sensitivity is negatively correlated with the crack period length and positively correlated with the crack period number; Mapping the linear range to the direction constraint of the crack period distribution gradient coefficient, where the positive gradient coefficient is used to expand the high-voltage detection range of the sensor, and the negative gradient coefficient is used to improve the low-voltage sensitivity of the sensor; Mapping the spatial resolution to the lower limit constraint of the crack period length and the upper limit constraint of the crack period number; Define the lower limit constraint of the processing energy and the upper limit constraint of the processing speed according to the material tolerance and the laser equipment capabilities.

3. The preparation method according to claim 1, characterized in that, Based on the active regression algorithm, iteratively search for all feasible solutions of laser processing parameters and crack structure parameters that meet the constraint conditions, and output all parameter combinations of the target performance requirements including: Generate an initial parameter combination set through Latin hypercube sampling, covering the parameter space of processing energy, processing speed, fracture cycle length, number of fractures, and gradient coefficient; Use a Gaussian process regression model to establish a non-linear mapping relationship between parameters and performance, and predict the performance indicators of candidate parameter combinations; Select the next candidate parameter combination based on the expected improvement criterion, preferentially explore the region where the predicted performance is better than the current optimal solution, iteratively update the Gaussian process regression model and screen for feasible solutions until the performance tolerance is met or the maximum number of iterations is reached; Output all parameter combinations that meet the constraint conditions and the predicted values of the parameter combination performance.

4. The preparation method according to claim 1, characterized in that Based on the laser processing parameters in the first parameter combination and the first array structure design drawing, prepare a flexible pressure sensor, and obtain the first flexible pressure sensor including: Cut the conductive silicone according to the preset size, soak the cut conductive silicone in absolute ethanol and perform ultrasonic treatment; Cut out the FCP interdigital electrode layer and weld the FCP interdigital electrode layer to the conductive silicone; According to the first array structure design drawing, use a laser to mark an array fracture structure on the surface of the conductive silicone, and soak it in absolute ethanol again and perform ultrasonic treatment after the laser marking is completed to obtain the first flexible pressure sensor.

5. The preparation method according to claim 1, wherein After step S6, it further includes encapsulating the second flexible pressure sensor with hot melt adhesive or sewing thread; When using hot melt adhesive for encapsulation, obtain a flexible fabric and a sheet of hot melt adhesive according to the size of the second flexible pressure sensor; Stack the cut-out hollow sheet of hot melt adhesive on the FCP interdigital electrode layer and hot press it at 120 degrees Celsius for 20 seconds using a hot press to obtain the final flexible pressure sensor.

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