An omnidirectional detection sensor based on periodic composite hole structure and its preparation method

Abstract

The present invention discloses an omnidirectional detection sensor based on a periodic composite hole structure and a preparation method thereof, belonging to the technical field of flexible sensor preparation. The sensor includes a substrate, a sensing layer and a packaging layer; a plurality of sensing areas are arranged on the substrate, each sensing area is arranged along the radial direction of the substrate, and the angles between adjacent sensing areas are equal; a hole array is arranged at the sensing area, and the form of the hole array arranged on each sensing area is different; stress isolation gaps are arranged on both sides of the sensing area; the sensing layer is arranged above the sensing area, and a conductive silver paste layer is also arranged at the end of the sensing layer, a copper tape is wrapped around the conductive silver paste layer, and a wire is pressed between the copper tape and the conductive silver paste layer; the packaging layer is arranged above the sensing layer. The present invention can output a multi-channel signal with more obvious directional characteristics, which is helpful to achieve high-precision and high-resolution omnidirectional detection tasks.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible sensor preparation, and in particular relates to an omnidirectional detection sensor based on a periodic composite hole structure and a preparation method thereof. Background Art

[0002] As an important component of wearable devices, stretchable strain sensors capture deformation information by attaching to the surface of human skin, and have a wide range of application scenarios in the fields of human-computer interaction, motion detection, and health monitoring. In many of the above application scenarios, stretchable strain sensors not only need to know the deformation amplitude of the attachment position, but also need to feedback the deformation direction to achieve functions such as precise positioning, dynamic monitoring, and optimized control. However, most stretchable strain sensors work in a uniaxial strain sensitive mode, which is essentially difficult to achieve accurate perception of omnidirectional stretching.

[0003] In some existing omnidirectional detection systems, common sensor unit placement methods include "claw", "rose" and "cross". Since the sensor units in the central symmetrical position experience the same deformation in any stretching direction, the sensor units with the same sensitivity performance will produce similar signal responses, making it difficult for the omnidirectional detection system to distinguish the multi-channel response differences in different loading directions. Summary of the invention

[0004] Based on the above technical problems, the present invention proposes an omnidirectional detection sensor based on a periodic composite hole structure and a preparation method thereof.

[0005] The technical solution adopted by the present invention is:

[0006] An omnidirectional detection sensor based on a periodic composite hole structure comprises a substrate, a sensing layer and a packaging layer; a plurality of sensing regions are arranged on the substrate, each sensing region is arranged along the radial direction of the substrate, and the angles between adjacent sensing regions are equal;

[0007] A hole array is arranged at the sensing area, and the hole array arranged on each sensing area has a different form;

[0008] Stress isolation gaps are provided on both sides of the sensing area;

[0009] The sensing layer is arranged above the sensing area, a conductive silver paste layer is arranged at the end of the sensing layer, a copper tape is wound around the conductive silver paste layer, and a wire is pressed between the copper tape and the conductive silver paste layer;

[0010] The packaging layer is arranged above the sensing layer.

[0011] Preferably, the hole shape in the hole array is a circle, a square, a regular hexagon, or a new shape formed by rotating a square or a regular hexagon by 30° and 45° respectively;

[0012] The arrangement of the hole array on each sensing area includes the following: all columns use the same aperture, the first 1 / 2 column and the last 1 / 2 column use different apertures, and the first 1 / 3 column, the middle 1 / 3 column and the last 1 / 3 column all use different apertures.

[0013] The present invention also provides a method for preparing the omnidirectional detection sensor based on the periodic composite hole structure as described above, comprising the following steps:

[0014] a. Prepare substrate;

[0015] Pour Ecoflex reagent into the template, then heat it in an oven, wait for it to solidify and shape, and then peel it off to obtain the substrate;

[0016] The template includes a circular plate body, a flange is arranged around the edge of the circular plate body, and a plurality of sensing forming areas are arranged on the circular plate body, each sensing forming area is arranged along the radial direction of the circular plate body, and the angles between adjacent sensing forming areas are equal;

[0017] A columnar array is provided at the sensing forming area, and the columnar array arranged at each sensing forming area is different at least in the columnar cross-sectional shape, columnar cross-sectional area or columnar arrangement mode;

[0018] Long strip-shaped protrusions are arranged on both sides of the sensing forming area;

[0019] A sensing region is formed on the corresponding substrate, a hole array is arranged at the sensing region, and stress isolation gaps are formed on both sides of the sensing region;

[0020] b. Coating with conductive material;

[0021] placing a mask plate on the substrate so that the four sensing areas are exposed, and then coating the exposed areas with a conductive material to form a conductive layer;

[0022] c. Packaging;

[0023] Copper tape is wound around both ends of the conductive layer as an interface, and a wire is led out; the copper tape passes through the stress isolation gap and is wound around the conductive layer; the conductive layer is then packaged to obtain an omnidirectional detection sensor based on a periodic composite hole structure.

[0024] The beneficial technical effects of the present invention are:

[0025] The present invention relates to an omnidirectional detection sensor based on a periodic composite hole structure and a preparation method thereof. The sensitivity of the prepared omnidirectional detection sensor is different. The sensing area or sensing unit is combined in a "cross shape" and can output a multi-channel signal with more obvious directional characteristics, which is helpful to achieve high-precision and high-resolution omnidirectional detection tasks. The present invention introduces a heterogeneous substrate structure with periodic composite hole characteristics to produce an obvious strain zoning phenomenon on the surface of the elastomer film and obtain sensitivity gain. The stress distribution of the carbon nanotube sensing layer is modulated based on the hole parameters, and stress isolation gaps are added on both sides of the sensing area to protect the sensing area from interference perpendicular to the main strain direction, thereby better highlighting the directional characteristics.

[0026] The preparation method of the omnidirectional detection sensor of the present invention has the advantages of simplicity and flexibility, and can be further applied to the preparation of various types of sensors such as resistive, capacitive and triboelectric sensors, providing unique prospects for wider applications such as tactile sensors, soft robots and health monitoring technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structural principle of an implementation of an omnidirectional detection sensor based on a periodic composite hole structure of the present invention;

[0028] Figure 2 It is a schematic diagram of the structural principle of a single sensing area in the omnidirectional detection sensor of the present invention;

[0029] Figure 3 It is a schematic diagram of the cross-sectional structure principle of the end of the sensing area in the omnidirectional detection sensor of the present invention;

[0030] Figure 4 It is a flow chart of a method for preparing an omnidirectional detection sensor based on a periodic composite hole structure in an embodiment of the present invention;

[0031] Figure 5 A schematic structural diagram of an embodiment of a template for preparing a substrate used in the preparation method of the present invention;

[0032] Figure 6 for Figure 5 Another angle view of

[0033] Figure 7 A schematic structural diagram of an embodiment of a substrate prepared in the present invention;

[0034] Figure 8 It is a schematic diagram of the structural principle of the covering mask plate in the preparation method of the present invention;

[0035] Fig. 9It is a finite element stress analysis model of a single sensing unit (hole array structure and flat membrane structure) in an embodiment of the present invention;

[0036] Fig.10 It is a sensitivity curve diagram of the hole array structure and the flat membrane structure sensing unit in the embodiment of the present invention;

[0037] Fig.11 is a sensitivity curve diagram of sensing units with different aperture sizes in an embodiment of the present invention;

[0038] Fig.12 is a sensitivity curve diagram of the sensor units with different hole pattern types in the embodiment of the present invention;

[0039] Fig.13 is a sensitivity curve diagram of the sensor unit with different hole arrangement modes in the embodiment of the present invention;

[0040] Fig.14 Selection of hole combinations for omnidirectional detection sensors with different sensitivity of sensing units and with consistent sensitivity of sensing units (control group) in the embodiment of the present invention;

[0041] Fig.15 It is a two-level difference bar graph of the multi-channel resistance response of the omni-directional detection sensor when θ=0° in an embodiment of the present invention;

[0042] Fig.16 It is a two-level difference bar graph of the multi-channel resistance response of the omni-directional detection sensor when θ=90° in an embodiment of the present invention;

[0043] Fig.17 It is a signal channel indication diagram of the omnidirectional detection sensor in an embodiment of the present invention.

[0044] In the figure: 1-circular plate, 2-flange, 3-sensing formation area, 4-substrate, 5-mask plate, 6-sensing layer, 7-conductive silver paste layer, 8-copper tape, 9-conducting wire, 10-packaging layer;

[0045] 301 - columnar body array, 302 - long strip protrusions; 401 - sensing area, 402 - hole array, 403 - stress isolation gap, 404 - thin film layer; 501 - through hole, 502 - strip hole. DETAILED DESCRIPTION

[0046] The present invention discloses an omnidirectional detection sensor based on a periodic composite hole structure and a preparation method thereof to solve the problem of insufficient directional perception of existing flexible strain sensors. In view of the above technical problems, the present invention designs a variety of composite hole combinations for constructing sensing units (sensing areas) with different sensitivity performance. The hole structure is located below the elastomer film. Thanks to its unique heterogeneous substrate structure, the strain conditions in different areas of the conductive layer are significantly different. Adjusting the structural parameters or the hole combination to change the strain distribution of the substrate film can accurately control the sensitivity performance of the sensing unit. The method is simple and flexible and can be further applied to various types of sensors such as resistive, capacitive and triboelectric sensors. Compared with traditional omnidirectional detection devices, the advantage of using sensing units with different sensitivity performance in the present invention is that the difference between multi-channel response signals can be amplified, making the signal distinction of different directions of stretching more obvious. The present invention realizes high-resolution omnidirectional detection, highlights the directional characteristics with the help of a simple strain partitioning method, and provides a multifunctional option for epidermal and implantable omnidirectional detection applications.

[0047] Example 1

[0048] like Figure 1 , Figure 2 , Figure 7 As shown, an omnidirectional detection sensor based on a periodic composite hole structure includes a substrate 4, a sensing layer 6 and an encapsulation layer 10. Four sensing areas 401 are arranged on the substrate 4, and each sensing area 401 is arranged along the radial direction of the substrate, and there is a 90-degree angle between adjacent sensing areas, so that the four sensing areas are distributed in a cross shape as a whole. A hole array 402 is arranged at the sensing area 401, and the form of the hole array arranged on each sensing area is different. For example, the hole shape in the hole array is set to be a circle, a square, a regular hexagon, or a new shape formed by rotating a square or a regular hexagon by 30° and 45° respectively. The arrangement of the hole array on each sensing area includes the following: all columns use the same aperture, the first 1 / 2 column and the last 1 / 2 column use different apertures, and the first 1 / 3 column, the middle 1 / 3 column and the last 1 / 3 column all use different apertures.

[0049] like Figure 3 As shown, stress isolation gaps 403 are provided on both sides of the sensing area 401. The sensing layer 6 is provided above the sensing area, and a conductive silver paste layer 7 is provided at the end of the sensing layer 6. A copper tape 8 is wound around the conductive silver paste layer 7, and a wire 9 is pressed between the copper tape 8 and the conductive silver paste layer 7. The packaging layer 10 is provided above the sensing layer 6.

[0050] The substrate is an Ecoflex elastomer film containing a hole array structure and a hollow stress isolation structure, which is prepared by a template method. The sensing layer is multi-walled carbon nanotubes. After multi-walled carbon nanotubes are applied to the surface of the substrate sensing area, the sensor is encapsulated using Ecoflex.

[0051] The present invention combines multiple sensor units according to a certain geometric structure to form an array, and can achieve high-precision detection of the stretching direction by means of multi-channel response differences. Further construction of a sensor array with different sensitivity performance can amplify anisotropy, which is of great significance for improving the recognition accuracy of the omnidirectional detection system.

[0052] like Fig.14 As shown, the hole combination of the omnidirectional detection sensor is a circular 12R 1.5 、Rhombus 12R 1.5 、Circular 4R 1.5 -4R1-4R 0.5 and round 12R 0.5 The sensitivity of the sensor units formed by these hole combinations is quite different. 1.5 -4R1-4R 0.5 The hole combination of 20 holes is used as the control group to verify the effectiveness of amplifying the directional characteristics of the sensing units with differentiated sensitivity.

[0053] After comparison, it was found that Figure 15-17 As shown in the figure, Ⅰ, Ⅱ, Ⅲ, and Ⅳ represent the four sensing units of the omnidirectional detection sensor, which can also be understood as the number of the signal channel. It can be seen from the figure that the response signals of the sensing units in the central symmetric position of the omnidirectional detection sensor with differentiated sensitivity sensing units under the conditions of 20% strain and 0° and 90° stretching show obvious differences. For example, under the conditions of 0° and 20%, the main strain direction of sensing units Ⅰ and Ⅲ is the same as the stretching direction. After the sensitivity differentiation processing, the two-level difference data difference of the voltage output waveform of the two sensing units increases from 0.03 to 0.15; the data difference under the conditions of 90° and 20% is the most obvious. After the sensitivity differentiation layout processing, the two-level difference data difference of the output waveform of sensing units Ⅱ and Ⅳ with the same stretching direction and main strain direction increases from 0.01 to 0.29, and the voltage difference of the two channels is expanded by 29 times.

[0054] Example 2

[0055] like Figure 4 As shown, the preparation method of the omnidirectional detection sensor based on the periodic composite hole structure includes the following steps:

[0056] 1. Prepare substrate;

[0057] Pour the Ecoflex reagent into the template, then place it in an oven to heat it, wait for it to solidify and shape, and then peel it off to obtain the substrate.

[0058] The present invention utilizes a template method to construct a substrate having a hole array and a hollow stress isolation structure (stress isolation gap), including a combination of four holes, and the parameters and arrangement of the holes can be adjusted according to actual sensitivity requirements.

[0059] Before constructing a substrate with a hole array structure and a hollow stress isolation structure, it is necessary to prepare the Ecoflex reagent and bake and cure it. The specific steps are as follows:

[0060] Step 1.1. Mix Ecoflex A and B glue in a mass ratio of 1:1 and stir thoroughly, then vacuum degas the mixed solution to obtain Ecoflex reagent. Pour the vacuum degassing solution (Ecoflex reagent) evenly on the template, which has a variety of hole combinations, and finally bake it in an oven at 55° for 30 minutes.

[0061] In this embodiment, the stirring time should be more than 10 minutes to ensure that EcoflexA and EcoflexB are fully mixed. A large number of bubbles will be generated during this process.

[0062] The process of vacuum degassing is: put the mixed solution into a vacuum machine for vacuum treatment until there are no more bubbles in the liquid. The time the mixed solution is in the vacuum machine should not be too long (about 1 minute), otherwise it will solidify prematurely and be difficult to shape.

[0063] like Figure 5 , Figure 6 As shown, the template includes a circular plate body 1, a flange 2 is arranged around the edge of the circular plate body 1, and four sensing forming areas 3 are arranged on the circular plate body 1. Each sensing forming area is arranged along the radial direction of the circular plate body, and there is a 90-degree angle between adjacent sensing forming areas, so that the four sensing forming areas are distributed in a cross shape as a whole. A columnar array 301 is arranged at the sensing forming area, and the columnar array arranged at each sensing forming area is different at least in the cross-sectional shape of the columnar body, the cross-sectional area of ​​the columnar body, or the arrangement of the columnar body. In other words, there are multiple options for the combination of holes on the corresponding substrate, including changing the three factors of hole radius, hole shape, and arrangement mode. Arranging and combining these parameters can enrich the sensitivity selection of the sensing unit. Long strip-shaped protrusions 302 are arranged on both sides of the sensing forming area 3.

[0064] like Figure 7As shown, a sensing area 401 is formed on the corresponding substrate 4, a hole array 402 is arranged at the sensing area, and stress isolation gaps 403 are formed on both sides of the sensing area 401. The hole array structure can induce strain partitioning of a specific sensitive area to achieve customized sensitivity. The stress isolation gap 403 can eliminate undesirable resistance response to a certain extent, enhance the sensing unit's perception of a single strain direction, and make the response waveform more distinguishable.

[0065] Furthermore, the heights of the columns in the columnar arrays of all the sensing areas are equal, and the heights of the columns are less than the heights of the long strip protrusions 302, and the heights of the long strip protrusions 302 are less than or equal to the heights of the flanges 2, so as to ensure that the film above the holes in the hole array is not broken. Figure 2 As shown, a thin film layer 404 is formed at the bottom of the substrate 4. Then, a conductive material is coated on the surface of the thin film layer 404 to form the sensing layer 6.

[0066] For example, the radius of the circular plate 1 is 60 mm, which includes four highly consistent periodic composite cylindrical arrays distributed in a cross shape. This area belongs to the sensing area and is 44 mm*10 mm in size. At the same time, it contains two long rectangular bodies on both sides, which are 47 mm*1 mm in size.

[0067] The hole shapes in the hole array 402 are circular, square, regular hexagonal, or new shapes formed by rotating the square and regular hexagon by 30° and 45° respectively. The hole array arrangement in each sensing area includes the following: all columns use the same aperture, the first 1 / 2 column and the last 1 / 2 column use different apertures, and the first 1 / 3 column, the middle 1 / 3 column and the last 1 / 3 column all use different apertures.

[0068] Specifically, the hole combination of the template is mainly constructed by changing three structural parameters, including aperture size, pattern type and arrangement. For example, the aperture size considers three parameters with a radius of 1.5mm, 1mm and 0.5mm; five types of patterns are considered, among which the hexagon and square are rotated 30° and 45° respectively to form a new figure; three arrangements are considered, namely 12 columns with one aperture, 6 columns plus 6 columns with different apertures, and 4 columns plus 4 columns plus 4 columns with different apertures. Diversified structural parameters can give the sensor unit a rich selection of sensitivity performance.

[0069] Step 1.2. Peel the cured Ecoflex substrate from the template with a utility knife, and then place the laser-cut wood mask on the substrate.

[0070] The peeled Ecoflex substrate needs to include a periodic composite hole structure (hole array 402) and a hollow stress isolation structure (stress isolation gap 403), such as Figure 3 , Figure 7 As shown, one end of the hole array 402 is closed by a thin film layer 404 formed on one side of the substrate to ensure that the thin film above the holes is not broken.

[0071] b. Coating with conductive material;

[0072] like Figure 8 As shown, the mask plate 5 is placed on the substrate so that the four sensing areas on the substrate are exposed, and then a conductive material is coated on the exposed areas to form a conductive layer.

[0073] The mask plate 5 is circular in shape and covers the substrate. A through hole 501 is provided at a position of the mask plate facing the sensing area, and strip holes 502 for correspondingly arranging wires are provided at both ends of the through hole.

[0074] The conductive material is multi-walled carbon nanotubes; conductive silver paste is also applied on the surfaces of both ends of the conductive layer.

[0075] The mask plate 5 can be a laser-engraved wooden mask plate. The function of the mask plate is to prevent the conductive layer from being coated outside the sensing area when the conductive material such as multi-walled carbon nanotubes is subsequently coated, so as to ensure that each sensing unit has the same size.

[0076] Specifically, when coating the conductive material, the multi-walled carbon nanotube material is applied to the sensing area, which is above the hole array, and the stress isolation gaps 403 on both sides are protected.

[0077] Fig. 9 This is a finite element stress analysis model of a hole array structure and a flat membrane structure. ε1 and ε2 represent the strain values ​​in the hole area and the non-hole area, and ε0 represents the strain value of the flat membrane structure. This figure is intended to illustrate that stress concentration in the hole area causes strain partitioning of the sensor to obtain sensitivity gain. The purpose of the hole array is to cause strain partitioning of the elastomer film to achieve sensitivity customization.

[0078] By measuring the sensitivity curve of a single sensing unit and comparing the sensitivities of devices with different hole parameters and combinations, it is found that the device with a circular aperture of 1.5 mm has the highest sensitivity, reaching 368, which is nearly 7 times higher than the sensitivity of the flat membrane structure device, verifying the effectiveness of strain partitioning in obtaining sensitivity gain, such as Fig.10 shown.

[0079] The gauge factor, or sensitivity, is GF. GF is defined by the following formula: GF = (ΔR / R0) / ε, where ΔR / R0 and ε refer to the relative resistance change and strain, respectively.

[0080] The role of the hollow stress isolation structure (stress isolation gap) is to eliminate the unexpected resistance response to a certain extent, enhance the sensing unit's perception of a single strain direction, and make the distinction of the response waveform more obvious.

[0081] c. Packaging;

[0082] Copper tape is wound around both ends of the conductive layer as an interface, and a wire is led out; the copper tape passes through the stress isolation gap and is wound around the conductive layer; the conductive layer is then packaged to obtain an omnidirectional detection sensor based on a periodic composite hole structure.

[0083] Specifically, the number of interfaces can be set to 8, and four signals can be output. There are 4 sensing areas, which correspond to the hole array structure one by one. The orientation of the sensing units determines the main strain direction they sense.

[0084] Specifically, the rubber is removed from both ends of the wire to expose the copper wire, and the copper wire is wound into a disc shape and placed on the conductive silver paste, fixed by hot pressing, and finally the stress isolation gap is used to cover the silver paste area with copper tape and wrap it around, and PU tape is used to wrap and fix the broken end of the copper tape.

[0085] The packaging process is as follows: after wrapping the copper tape on the conductive layer, pour the Ecoflex reagent evenly on the surface of the four sensing areas, and then put it into an oven for curing to obtain an omnidirectional detection sensor based on a periodic composite hole structure.

[0086] More specifically, a hollow stress isolation structure is used to wrap a circle of copper tape as an interface, and the sensing area is encapsulated at the same time.

[0087] In step 2, after coating multi-walled carbon nanotubes at corresponding positions of the omni-directional detection sensor substrate with a hole array structure and a hollow stress isolation structure using a laser-engraved mask plate, apply conductive silver paste on the ends of the sensors, remove the rubber at both ends of the wire to expose the copper wire, and wind the copper wire into a disc shape, place it on the silver paste, and hot-press it at 120° for 30 minutes to fix it. Finally, use the hollow stress isolation structure to cover the silver paste area with copper tape and wrap it around, and use PU tape to wrap the broken end of the copper tape to fix it.

[0088] The device with copper tape is packaged. The packaging process is as follows:

[0089] The vacuum-treated Ecoflex mixed liquid is evenly poured on the surface of the four sensing areas of the device and cured to obtain an omnidirectional detection sensor based on a periodic composite hole structure.

[0090] The Ecoflex mixed solution is also prepared by mixing Ecoflex glue A and glue B in a mass ratio of 1:1. First, glue A and glue B are mixed and stirred for one minute with a stirring rod, and then the mixed solution of glue A and glue B is placed in a vacuum machine for vacuum treatment until there are no more bubbles in the liquid.

[0091] Curing means pouring the vacuum-treated Ecoflex mixture evenly on the surface of the four sensing areas of the device, and then putting it into an oven for curing. The curing temperature and curing time here can refer to the curing temperature and time above, such as curing at 55° for 30 minutes.

[0092] This embodiment experiments with hole combinations and parameters of different sensitivities of a sensor unit based on a periodic composite hole structure, explores the sensitivity of the sensor unit with different aperture sizes, pattern types and arrangements, and verifies the effectiveness of sensitivity control based on strain partitioning modulation effect.

[0093] like Fig.11 As shown in the figure, the sensitivity curves of the sensing units with circular holes and aperture sizes R of 0.5mm, 1mm and 1.5mm were tested. After linear fitting, the strain coefficients GF at 60%-100% strain were 21.3, 44.4 and 77.3 respectively. It can be concluded that the larger the aperture, the more sensitive the sensor.

[0094] like Fig.12 As shown in the figure, the sensitivity curves of the sensing units with patterns of circle, diamond, hexagon, square and oblique hexagon were tested, among which the square and oblique hexagon were obtained by rotating the diamond and hexagon by 45° and 30° respectively. Linear fitting was performed under 160%-200% strain, and the trends of the three basic polygonal sensitivity curves from high to low were circle (GF=368), hexagon (GF=250) and diamond (GF=192). Without considering the rotation, the results showed that the larger the hole area and the smoother the angle, the higher the sensitivity of the hole pattern device. After rotation, the sensitivity of the device showed a significant decrease, which was square (GF=121) and oblique hexagon (GF=58), respectively. This may be attributed to the reduction of the hole width after rotation, resulting in a reduction in the strain partitioning influence area.

[0095] like Fig.13 As shown, the tested arrangements are 12R 1.5 、6R 1.5 -6R1, 4R 1.5 -4R1-4R 0.5The sensitivity curve of the sensor unit with circular hole shape. The number in front of R represents the number of hole columns, R represents the hole radius, and the subscript of R represents the hole radius value. Under 140%-200% strain, the strain factors GF of the above three sensor units are 368.0, 122.0 and 88.7 respectively.

[0096] By arranging and combining the three sensitivity influencing factors of aperture size, pattern type and arrangement method, more sensitive sensing units can be constructed, achieving precise control of the sensitivity factor in the range of 55 to 368.

[0097] The preparation method of the present invention amplifies the multi-channel response difference of the sensor array output formed by combining according to a certain geometric structure, thereby improving the recognition accuracy and resolution of the stretching direction of the omnidirectional detection system.

[0098] The omnidirectional detection sensor based on the periodic composite hole structure prepared in this embodiment can output a signal with more obvious directional characteristics than the traditional direction detection device. Combined with the artificial intelligence classification and recognition algorithm, it can complete high-precision and high-resolution omnidirectional detection tasks.

[0099] The omnidirectional detection sensor based on the periodic composite hole structure in the embodiment of the present invention can be used in the field of fitness scenarios. It can reduce the risk of injury and improve the exercise effect by identifying the amplitude and direction of skin stretching, monitoring the standard degree of movement and the force state of muscles.

[0100] The omnidirectional detection sensor based on the periodic composite hole structure in the embodiment of the present invention also has broad application prospects in the field of artificial interaction. By attaching it to the joints of the soft robot, it can accurately locate its action state by using the response difference of multi-channel signals, and feed back reliable direction and angle information to the control system.

[0101] Of course, the above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It should be noted that all equivalent substitutions and obvious deformation forms made by any technician familiar with the field under the guidance of this specification fall within the essential scope of this specification and should be protected by the present invention.

Claims

1. An omnidirectional detection sensor based on a periodic composite hole structure, characterized in that: It includes a substrate, a sensing layer and a packaging layer; a plurality of sensing regions are arranged on the substrate, each sensing region is arranged along the radial direction of the substrate, and the angles between adjacent sensing regions are equal; A hole array is arranged at the sensing area, and the hole array arranged on each sensing area has a different form; Stress isolation gaps are provided on both sides of the sensing area; The sensing layer is arranged above the sensing area, a conductive silver paste layer is arranged at the end of the sensing layer, a copper tape is wound around the conductive silver paste layer, and a wire is pressed between the copper tape and the conductive silver paste layer; The packaging layer is arranged above the sensing layer.

2. The omnidirectional detection sensor based on a periodic composite hole structure according to claim 1, characterized in that: The hole array has a shape of a circle, a square, a regular hexagon, or a new shape formed by rotating a square by 30° or 45°, or a new shape formed by rotating a regular hexagon by 30° or 45°; The arrangement of the hole array on each sensing area includes the following: all columns use the same aperture, the first 1 / 2 column and the last 1 / 2 column use different apertures, and the first 1 / 3 column, the middle 1 / 3 column and the last 1 / 3 column all use different apertures.

3. The omnidirectional detection sensor based on a periodic composite hole structure according to claim 1, characterized in that: A total of four sensing regions are arranged on the substrate, and adjacent sensing regions form an angle of 90 degrees, so that the four sensing regions are distributed in a cross shape as a whole.

4. A method for preparing an omnidirectional detection sensor based on a periodic composite hole structure as described in any one of claims 1 to 3, characterized in that: The following steps are involved: a. Prepare substrate; Pour Ecoflex reagent into the template, then heat it in an oven, wait for it to solidify and shape, and then peel it off to obtain the substrate; The template includes a circular plate body, a flange is arranged around the edge of the circular plate body, and a plurality of sensing forming areas are arranged on the circular plate body, each sensing forming area is arranged along the radial direction of the circular plate body, and the angles between adjacent sensing forming areas are equal; A columnar array is provided at the sensing forming area, and the columnar array arranged at each sensing forming area is different at least in the columnar cross-sectional shape, columnar cross-sectional area or columnar arrangement mode; Long strip-shaped protrusions are arranged on both sides of the sensing forming area; A sensing region is formed on the corresponding substrate, a hole array is arranged at the sensing region, and stress isolation gaps are formed on both sides of the sensing region; b. Coating with conductive material; placing a mask plate on the substrate so that the four sensing areas are exposed, and then coating the exposed areas with a conductive material to form a conductive layer; c. Packaging; Copper tape is wound around both ends of the conductive layer as an interface, and a wire is led out; the copper tape passes through the stress isolation gap and is wound around the conductive layer; the conductive layer is then packaged to obtain an omnidirectional detection sensor based on a periodic composite hole structure.

5. The method for preparing an omnidirectional detection sensor based on a periodic composite hole structure according to claim 4, characterized in that: In step a, Ecoflex reagent is prepared by the following steps: Mixing Ecoflex glue A and glue B in a mass ratio of 1:1, and stirring for 10-20 minutes to obtain a mixed solution; then performing vacuum defoaming treatment on the mixed solution to obtain Ecoflex reagent; The temperature of the oven is controlled to be 55-60°C and the baking time is 20-30 minutes.

6. The method for preparing an omnidirectional detection sensor based on a periodic composite hole structure according to claim 4, characterized in that: In step a: the heights of the columns in the columnar arrays of all sensing forming areas are equal, and the heights of the columns are less than the heights of the long strip-shaped protrusions, and the heights of the long strip-shaped protrusions are less than or equal to the heights of the flanges.

7. The method for preparing an omnidirectional detection sensor based on a periodic composite hole structure according to claim 4, characterized in that: In step a: the hole shape in the hole array is a circle, a square, a regular hexagon, or a new shape formed by rotating the square by 30° or 45°, or a new shape formed by rotating the regular hexagon by 30° or 45°; The arrangement of the hole array in each sensing area includes the following: all columns use the same aperture, the first 1 / 2 column and the last 1 / 2 column use different apertures, and the first 1 / 3 column, the middle 1 / 3 column and the last 1 / 3 column all use different apertures.

8. The method for preparing an omnidirectional detection sensor based on a periodic composite hole structure according to claim 4, characterized in that: In step b: the mask plate is circular, covers the substrate, a through hole is arranged at the position of the mask plate facing the sensing area, and strip holes for correspondingly arranging wires are arranged at both ends of the through hole.

9. The method for preparing an omnidirectional detection sensor based on a periodic composite hole structure according to claim 4, characterized in that: In step b: the conductive material is multi-walled carbon nanotubes; conductive silver paste is also applied to the surfaces of both ends of the conductive layer; Remove the rubber from both ends of the wire to expose the copper wire, and then wind the copper wire into a disc shape and place it on the conductive silver paste. Fix it with hot pressing. Finally, use the stress isolation gap to cover the conductive silver paste area with copper tape and wrap it around, and use PU tape to wrap and fix the broken end of the copper tape.

10. The method for preparing an omnidirectional detection sensor based on a periodic composite hole structure according to claim 4, characterized in that: In step c, the packaging process is as follows: after the copper tape is wrapped around the conductive layer, the Ecoflex reagent is evenly poured on the surface of the sensing area, and then placed in an oven for curing, thereby obtaining an omnidirectional detection sensor based on a periodic composite hole structure.

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