Preparation method of sensor based on single-plane micro-tactile structure

Abstract

The present invention discloses a method for preparing a sensor based on a single-sided internal micro-tactile structure, comprising spin coating a PDMS prepolymer layer on a side surface of a film-making steel plate provided with an arc-shaped pit and pressing a PET layer on the PDMS prepolymer layer to obtain a PDMS substrate, evenly applying GPC ink on the upper surface of an ITO-PET layer to form a GPC layer, pressing one side surface of the PET layer on the GPC layer to obtain a first sensing structure layer; evenly applying GPC ink on the upper surface of an ITO-PET layer to form a GPC layer to obtain a second sensing structure layer, forming a contact sensing internal microstructure corresponding to sandpaper on one side surface of the second sensing structure layer; stacking the first sensing structure layer, the second sensing structure layer and the PDMS substrate from top to bottom in sequence to form a composite sensing structure layer, and the composite sensing structure layer is used for contact sensing. The method can prepare a sensor based on a single-sided internal micro-tactile structure at low cost and high efficiency, and improve the accuracy and stability of the tactile sensing structure in the sensor to identify three-dimensional texture information.

Description

Technical Field

[0001] The present invention relates to the technical field of tactile sensors, and in particular to a method for preparing a sensor based on a single-plane intra-micro tactile structure. Background Art

[0002] Human skin is not only an effective barrier to protect our body from external environmental damage, but also a complex sensor for us to perceive the surrounding environment, such as object shape, texture, hardness, temperature and humidity. Therefore, electronic skin that simulates the characteristics of human skin has great application potential in the fields of robotics, medical devices and prostheses. In recent years, there have been many studies on the various characteristics of electronic skin, including stretchability, self-healing, tactile perception, humidity detection and temperature detection. Among them, tactile perception for identifying three-dimensional texture information is a research hotspot. Traditional smooth surface sensors are not suitable for identifying three-dimensional texture information because the friction between them and the texture is too small. Inspired by human fingerprints, reported tactile sensors generally have a unique sensing structure on the side of the sensor facing the object. For example, in 2018, the academic journal "small" published an article entitled "Fingerprint-Inspired Flexible Tactile Sensor for AccuratelyDiscerning Surface" in Volume 4, Issue 16. Texture" reports a new type of flexible tactile sensor assembled from single-walled carbon nanotubes (SWNTs), polyethylene (PE) and polydimethylsiloxane (PDMS) with a micro-pyramid array. The sensor has an interlocking and external micro-pyramid array, which can detect the shear force changes caused by the dynamic interaction between the external micro-pyramid structure and the surface of the material being tested. The minimum size of the identifiable micro-stripes is as low as 15μm×15μm (spacing×width). However, this unique micro-pyramid array is prepared by photolithography of silicon templates. Photolithography can only achieve some very basic three-dimensional shapes. At the same time, photolithography inevitably requires expensive equipment such as binary exposure machines and etching machines, and requires structural design, which has high economic and time costs. At the same time, a slight misalignment of the two symmetrical inner pyramid layers may cause the two layers of pyramids to break, that is, the sensor is short-circuited, and the texture width is estimated by the time difference of the current generated when the sensor slides over the texture. Therefore, the symmetrical inner pyramid layer is not suitable for identifying texture three-dimensional information. Summary of the invention

[0003] The embodiment of the present invention provides a method for preparing a sensor based on a single-sided internal micro-tactile structure, aiming to solve the problem of high preparation cost of sensors based on internal micro-tactile structures existing in the prior art methods.

[0004] In the first aspect, an embodiment of the present invention discloses a method for preparing a sensor based on a single-sided micro-tactile structure, the method comprising mixing a polydimethylsiloxane elastomer with a curing agent to obtain a PDMS prepolymer, adding graphene powder to the PDMS prepolymer and stirring to obtain a GPC ink; spin-coating the PDMS prepolymer layer on a side surface of a film-making steel plate provided with an arc-shaped pit, pressing a PET layer on the PDMS prepolymer layer, peeling off the film-making steel plate to obtain a PDMS substrate, and forming a strip-shaped convex structure corresponding to the arc-shaped pit on the upper surface of the PDMS substrate; evenly applying the GPC ink on the upper surface of the ITO-PET layer to form a GPC layer, pressing one side surface of another PET layer on the GPC layer, and heating the casting to form a GPC layer; After forming the GPC layer, peeling off the PET layer to obtain the first sensing structure layer; evenly coating the GPC ink on the upper surface of the ITO-PET layer to form the GPC layer, pressing the frosted surface of the sandpaper on the GPC layer, heating the cast-formed GPC layer, peeling off the sandpaper to obtain the second sensing structure layer, and forming a contact sensing internal microstructure corresponding to the sandpaper on one side surface of the second sensing structure layer; stacking the first sensing structure layer, the second sensing structure layer and the PDMS substrate from top to bottom in sequence to form a composite sensing structure layer, and the composite sensing structure layer is used for contact sensing; attaching the PI tape to the edge of the composite sensing structure layer to encapsulate and fix it to obtain the sensor, and the composite sensing structure layer is used for contact sensing.

[0005] Furthermore, before peeling off the film-forming steel plate to obtain the PDMS substrate, the method further includes curing the PDMS prepolymer layer in a temperature environment of 80-100°C.

[0006] Furthermore, before pouring the GPC ink on the upper surface of the ITO-PET layer and evenly coating it to form the GPC layer, the method further includes: attaching a PI tape to the side edge of the ITO-PET layer to measure the formation height of the GPC layer.

[0007] Furthermore, the height of the raised structure is 1-3 mm, and the width of the raised structure is 2-6 mm.

[0008] Furthermore, the grit of the sandpaper is 60-240.

[0009] In the second aspect, the present case discloses a sensor based on a single-sided micro-tactile structure, which is manufactured using the above-mentioned method for preparing a sensor based on a single-sided micro-tactile structure. The composite sensing structure layer includes the PDMS substrate, the first sensing structure layer and the second sensing structure layer. A flexible insulating layer is arranged on the side edges of the first sensing structure layer and the second sensing structure layer. A first flexible substrate and a first flexible electrode are formed on the surface of the second sensing structure layer facing the PDMS substrate, and a second flexible electrode and a second flexible substrate are formed on the surface of the first sensing structure layer away from the second sensing structure layer. The sensor also includes a PI tape encapsulated and fixed to the edge of the composite sensing structure layer.

[0010] Furthermore, the thickness of the first flexible substrate and the second flexible substrate is 6-50 μm.

[0011] Furthermore, the thickness of the first sensing structure layer and the second sensing structure layer is 200-400 μm, wherein the second sensing structure layer is provided with a contact sensing inner microstructure.

[0012] Furthermore, the PDMS substrate is made by curing a PDMS prepolymer obtained by mixing a polydimethylsiloxane elastomer with a curing agent.

[0013] Furthermore, the first sensing structure layer and the second sensing structure layer are made of GPC ink obtained by mixing PDMS prepolymer and graphene powder, and the mass proportion of graphene powder in the GPC ink is 15-45%.

[0014] Furthermore, the PDMS prepolymer is prepared by mixing a polydimethylsiloxane elastomer with a curing agent, and the mass ratio of the polydimethylsiloxane elastomer to the curing agent is 5:1.

[0015] The above-mentioned preparation method of the sensor based on the single-sided internal micro-tactile structure uses sandpaper as a template, and the tactile sensing layer structure prepared by using the micro-nano hierarchical structure of sandpaper makes the sensor have higher tactile sensing sensitivity. Compared with the traditional tactile sensor that needs to photolithograph the film-making template with complex structure, the present method only needs a simple arc-shaped pit film-making steel plate and sandpaper, and adopts the pressing film-making method to make the structural layer for tactile sensing. The preparation method is simple and low-cost. Compared with the interlocking internal microstructure in the traditional tactile sensor, the sensor prepared by the present method adopts a single-sided internal micro-tactile structure. The sensor based on the single-sided internal micro-tactile structure has a PDMS substrate with a raised structure, so that when the sensor is used to identify the three-dimensional information of the texture, the difference in piezoresistive characteristics caused by the misalignment of the interlocking internal microstructure can be avoided, thereby improving the accuracy and stability of identifying the three-dimensional information of the texture. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0017] Figure 1 A schematic flow chart of a method for preparing a sensor based on a single-plane micro-tactile structure according to an embodiment of the present invention;

[0018] Figure 2 A process flow chart of a composite sensing structure layer provided by an embodiment of the present invention;

[0019] Figure 3 Another process flow chart of manufacturing the composite sensing structure layer provided by an embodiment of the present invention;

[0020] Figure 4 Another process flow chart of manufacturing the composite sensing structure layer provided by an embodiment of the present invention;

[0021] Figure 5 A further process flow chart of manufacturing the composite sensing structure layer provided in an embodiment of the present invention;

[0022] Figure 6 A diagram of the application process of a sensor based on a single-plane micro-tactile structure provided by an embodiment of the present invention;

[0023] Figure 7 Another application process diagram of the sensor based on the single-plane micro-tactile structure provided by an embodiment of the present invention;

[0024] Figure 8 This is an application effect diagram of a sensor based on a single-plane micro-tactile structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Introduction of raw materials and equipment in the examples:

[0027] Sandpaper, purchased from Foshan Zhejiang Hardware Tools Co., Ltd., model 180 mesh;

[0028] Graphene powder, purchased from Shenzhen Suiheng Technology Co., Ltd., model 99% multilayer graphene;

[0029] Indium tin oxide conductive film (ITO-PET base film), purchased from Shenzhen Tianmi Shield Electronics Co., Ltd., model 150 ohm 0.05 μm thick;

[0030] Ethanol, purchased from Tafu Biotechnology (Shanghai) Co., Ltd., model 64-17-5;

[0031] Polydimethylsiloxane, purchased from Guangxiangsheng Chemical Products Business Department, Xizhang, Huishan District, model number SYLGARD184;

[0032] The curing agent was purchased from Guangxiangsheng Chemical Products Business Department, Xizhang, Huishan District, model number is DC184.

[0033] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0034] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0035] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0036] like Figure 1 As shown, Figure 1 The method flow chart of the method for preparing a sensor based on a single-plane micro-tactile structure is as follows. The method for preparing a sensor based on a single-plane micro-tactile structure provided in this embodiment includes steps S110 to S150.

[0037] S110, mixing a polydimethylsiloxane elastomer with a curing agent to obtain a PDMS prepolymer, adding graphene powder to the PDMS prepolymer and stirring to obtain a GPC ink.

[0038] GPC ink is prepared by mixing a polydimethylsiloxane elastomer with a curing agent to obtain a PDMS prepolymer, and then adding graphene powder to the obtained PDMS prepolymer and mechanically stirring it for 20-50 minutes at a stirring speed of 300-1000 r / min. The mass fraction of graphene in the GPC ink is 15-45%. In the best embodiment, the mass fraction of graphene in the GPC ink is 30%. After stirring, the GPC ink is obtained. The original state of the PDMS prepolymer and the GPC ink is liquid, which can be used for coating to form a thin film.

[0039] S120, spin-coat the PDMS prepolymer layer onto the surface of one side of the film-forming steel plate 1 where arc-shaped pits are provided, press the PET layer 2 onto the PDMS prepolymer layer, peel off the film-forming steel plate 1 to obtain the PDMS substrate 3, and form a strip-shaped protrusion structure corresponding to the arc-shaped pits on the upper surface of the PDMS substrate 3.

[0040] Prepare PDMS substrate 3, as Figure 2 As shown, a film-forming steel plate 1 is prefabricated, and arc-shaped strip pits are provided on one side surface of the film-forming steel plate 1, and the pits are used to form strip-shaped protrusions of the PDMS prepolymer coating. After the film-forming steel plate 1 is cleaned with ethanol and dried with nitrogen, the PDMS prepolymer is evenly applied to the side surface of the film-forming steel plate 1 provided with the arc-shaped strip pits. After the PET layer 2 is evenly applied, it is pressed onto the PDMS prepolymer layer that has been coated and formed. The coated film-forming steel plate 1 is placed in a thermal annealing environment under appropriate temperature conditions for 1-5 hours to achieve the curing of each coating. After the coating is cured, the film-forming steel plate 1 is peeled off to obtain a PDMS substrate 3 with a strip-shaped protrusion structure corresponding to the arc-shaped pits formed on the surface, and the PDMS substrate 3 contains the above-mentioned PET layer 2 for pressing.

[0041] S130, evenly apply GPC ink on the upper surface of the ITO-PET layer 11 to form a GPC layer 4, press one side surface of another PET layer 2 onto the GPC layer 4, heat the cast GPC layer 4, and then peel off the PET layer 2 to obtain the first sensing structure layer 7.

[0042] like Figure 3As shown, a first sensing structure layer 7 without an inner micro-tactile structure is prepared. The preparation of the first sensing structure layer 7 requires a PET layer 2, a GPC ink, and an ITO-PET layer 11. The PET layer 2 is cleaned with ethanol and then dried with nitrogen. Ethanol (95%) can be used to clean the PET layer 2. The PET layer 2 is immersed in an ethanol solution to remove residual impurities on the PET layer 2. Nitrogen is then blown into the cleaned PET layer 2 to dry it until no ethanol solution remains on the surface of the PET layer 2. The prefabricated GPC ink is evenly poured on the ITO-PET layer 11 and flattened to form a GPC layer 4. The PET layer 2 is pressed onto the GPC layer 4. A uniform coating is formed between the ET layer 2 and the ITO-PET layer 11, and the coating is sandwiched between two steel plates and thermally annealed for 1-5 hours under appropriate temperature conditions to achieve coating curing. The PET layer 2 is peeled off to obtain the first sensing structure layer 7 without microstructure on the surface of the ITO-PET layer 11. Before pouring the GPC ink, PI tape is attached to the two side edges of the ITO-PET layer 11. The part of the PI tape that is higher than the two side edges of the ITO-PET layer 11 forms a casting cavity with the upper surface of the ITO-PET layer 11. The GPC ink is poured in the casting cavity and heated and cured. The thickness of the GPC layer 4 can be changed by adjusting the attachment state of the PI tape.

[0043] S140, evenly apply GPC ink on the upper surface of the ITO-PET layer 11 to form a GPC layer 4, press the frosted surface of the sandpaper 5 onto the GPC layer 4, heat the cast GPC layer 4, peel off the sandpaper 5 to obtain the second sensing structure layer 8, and form a contact sensing internal microstructure corresponding to the sandpaper 5 on one side surface of the second sensing structure layer 8.

[0044] like Figure 4As shown, a second sensing structure layer 8 with an inner micro-tactile structure is prepared. The preparation of the second sensing structure layer 8 requires sandpaper 5, GPC ink and ITO-PET layer 11. The sandpaper 5 is cleaned with ethanol and then dried with nitrogen. Ethanol (95%) can be used to clean the sandpaper 5. The sandpaper 5 is immersed in an ethanol solution to remove residual impurities on the sandpaper 5. Nitrogen is then blown into the sandpaper 5 to dry the cleaned sandpaper 5 until no ethanol solution remains on the surface of the sandpaper 5. The prefabricated GPC ink is evenly poured on the ITO-PET layer 11 and flattened to form a GPC layer 4. The frosted surface of the sandpaper 5 is pressed on GPC layer 4, and then use a roller to assist in pressing the outer layer of sandpaper 5, the roller rolls back and forth on the sandpaper 5, and sandpaper 5 with different meshes can be used to prepare a second sensing structure layer 8 with a microstructure surface roughness that is different. The mesh of the sandpaper 5 used is 60-240 mesh, preferably 180 mesh, and a uniform coating is formed between the PET layer 2 and the ITO-PET layer 11. The coating is sandwiched between two steel plates and thermally annealed for 1-5 hours under appropriate temperature conditions to achieve coating curing. The sandpaper 5 is peeled off to obtain the second sensing structure layer 8 with a microstructure on the surface of the ITO-PET layer 11.

[0045] S150, stack the first sensing structure layer 7, the second sensing structure layer 8 and the PDMS substrate 3 from top to bottom in sequence to form a composite sensing structure layer 10, adhere the PI tape to the edge of the composite sensing structure layer 10 to encapsulate and fix it, and the composite sensing structure layer 10 is used for contact sensing.

[0046] The composite sensing structure layer 10 is packaged and fixed, such as Figure 5 As shown, the first sensing structure layer 7, the second sensing structure layer 8 and the PDMS substrate 3 prepared in the above steps are stacked from top to bottom in sequence to form a composite sensing structure layer 10, and the PI tape is attached to the edge of the composite sensing structure layer 10 to encapsulate and fix it to obtain a sensor. The composite sensing structure layer 10 is used for contact sensing. The selected tape can be a polyimide (PI) tape. The PI tape is attached to the edge of the composite sensing structure layer 10 to encapsulate and fix it to obtain a composite sensing structure layer 10 with a single-sided inner micro-tactile structure required for a sensor with a single-sided inner micro-tactile structure, which can be used for contact and sensing of the surface texture of the contact surface.

[0047] In actual use scenarios, a sensor with a single-sided internal micro-tactile structure having an asymmetric internal micro-tactile mechanism layer is prepared by the above-mentioned preparation method of the sensor based on the single-sided internal micro-tactile structure, which is used for texture contact sensing. This method includes the preparation of materials for the structural layer formation process. The sensor prepared by this method mainly includes a substrate and two sensing structure layers. The substrate and the two sensing structure layers are stacked to form the structural conditions of the sensor's texture contact and tactile sensing, wherein the flexible conductive base film is used as the ITO-PET layer 11, and the ITO-PET layer 11 is a conductive flexible film prepared by containing ITO (indium tin oxide) and PET (polyethylene glycol terephthalate); PDMS prepolymer is a polydimethylsiloxane prepolymer (polydimethylsiloxane), and graphene powder and PDMS are mechanically stirred to mix evenly to obtain GPC ink, which is also a graphene-PDMS composite material.

[0048] In summary, the composite sensing structure layer 10 of the sensor prepared by the above-mentioned method for preparing a sensor based on a single-sided internal micro-tactile structure can effectively avoid the problem of unstable sensor piezoresistive characteristics caused by the misalignment of the protruding structure of the interlocking internal microstructure of the sensing structure layer of the traditional tactile sensor, and the use of sandpaper 5 with a frosted surface for preparing the single-sided internal micro-tactile structure significantly reduces the preparation cost of the sensing structure layer in the sensor, simplifies the preparation process, and can be used for large-area sensor preparation arrays.

[0049] Furthermore, before peeling off the film-forming steel plate 1 to obtain the PDMS substrate 3, the method further includes curing the PDMS prepolymer layer in a temperature environment of 80-100°C.

[0050] Specifically, the thermal annealing temperature is optimized according to the physical and chemical properties of the PDMS prepolymer. It is usually preferred to perform thermal annealing at 90° C. to achieve solidification of the PDMS layer so that the PDMS layer can obtain the best physical properties during the tactile sensing process.

[0051] Furthermore, before pouring the GPC ink on the upper surface of the ITO-PET layer 11 and evenly spreading it to form the GPC layer 4 , the method further includes: attaching a PI tape to the side edge of the ITO-PET layer 11 to measure the formation height of the GPC layer 4 .

[0052] Specifically, the PI tape is attached to two opposite side edges of the prefabricated ITO-PET layer 11, and the portions of the PI tape on both sides that are higher than the upper surface of the ITO-PET layer 11 form a casting space with the upper surface of the ITO-PET layer 11. The PI tape on both sides is used to limit the height for casting GPC ink, which can be used as a limit on the thickness of the GPC layer 4.

[0053] Furthermore, the height of the raised structure is 1-3 mm, the width of the raised structure is 2-6 mm, and the mesh number of the sandpaper 5 is 60-240.

[0054] On the second aspect, the present case discloses a sensor based on a single-sided micro-tactile structure. The sensor is manufactured using the above-mentioned method for preparing a sensor based on a single-sided micro-tactile structure. The sensor has a sensing structure layer for contacting the texture and connecting the sensing circuit. The composite sensing structure layer includes a PDMS substrate, a first sensing structure layer 7 and a second sensing structure layer 8. The PDMS substrate, the first sensing structure layer 7 and the second sensing structure layer 8 are stacked to form a composite sensing structure layer 10. A flexible insulating layer is arranged on the side edges of the first sensing structure layer 7 and the second sensing structure layer 8. A first flexible substrate and a first flexible electrode are formed on the surface of the second sensing structure layer 8 facing the PDMS substrate. A second flexible electrode and a second flexible substrate are formed on the surface of the first sensing structure layer 7 away from the second sensing structure layer 8. The sensor also includes a PI tape encapsulated and fixed to the edge of the composite sensing structure layer.

[0055] Specifically, the sensor includes a PDMS substrate with a protruding structure, a second sensing structure layer 8, and a first sensing structure layer 7, which are sequentially arranged from top to bottom. The second sensing structure layer 8 forms an inner micro-tactile structure on one side of the surface facing the first sensing structure layer 7 and is in direct contact with the first sensing structure layer 7. The PDMS substrate, the second sensing structure layer 8, and the first sensing structure layer 7 constitute the sensing structure of the sensor. Through the above-mentioned preparation method, the ITO-PET layer 11 in the second sensing structure layer 8 is heated and cured to form a first flexible substrate and a first flexible electrode, and the ITO-PET layer 11 in the first sensing structure layer 7 is heated and cured to form a second flexible substrate and a second flexible electrode. The PI tape attached to the edges of both sides of the first sensing structure layer 7 and the second sensing structure layer 8 before pouring the GPC ink has insulating properties and can be used as a flexible insulating layer. The actual tactile sensor During the sensing process, the upper surface of the first flexible substrate is used to directly contact the texture. The first flexible electrode and the second flexible electrode can generate an induced current under pressure. The magnitude of the induced current changes due to the change in the contact area between the sensing structure layer and the texture. The induced current flows in the sensing circuit, and single-sided internal micro-tactile sensing occurs between the internal micro-tactile structure on the second sensing structure layer 8 and the first sensing structure layer 7 to construct a complete sensor tactile sensing process. Such single-sided internal micro-tactile sensing can avoid internal microstructure misalignment between different sensing structure layers and has a relatively stable piezoresistive characteristic.

[0056] Among them, the conductive material in the sensor includes any one or a combination of two or more of carbon-based nanoparticles, metal-based nanoparticles, and conductive nanowires, but is not limited to these. The flexible polymer includes any one or a combination of two or more of polydimethylsiloxane, polyurethane, thermoplastic polyurethane, and polyethylene, but is also not limited to these.

[0057] Preferably, the material of the first flexible substrate and the second flexible substrate includes any one or a combination of two or more of polyimide, polyethylene terephthalate, polytetrafluoroethylene, polycarbonate, and polyethylene naphthalate, and the material of the first flexible electrode and the second flexible electrode includes any one or a combination of two or more of indium oxide, metal nanowires made of silver, copper or gold, and carbon-based nanomaterials. Preferably, the flexible electrode is also electrically connected to the lead, and the lead includes any one or a combination of two or more of copper wire, copper tape, and conductive non-woven fabric, but is not limited to this.

[0058] During the use of the sensor, Figure 6 as well as Figure 7As shown, when the sensor is used for texture width recognition, a fixed force can be applied to the sensor to make it produce a very small initial response, and then the sensor is slid to contact the texture to be recognized, and the moment when the sensor just contacts the texture is recorded as time 1. The contact area of ​​the micro-tactile structure on a single surface of the sensor increases sharply, and the sensor current surges. The moment when the sensor just slides over the texture is recorded as time 2. The contact area of ​​the micro-tactile structure on a single surface of the sensor returns to its initial state, and the sensor current drops sharply. By comparing the time difference between these two time points and the displacement speed of the sensor, the width of the texture that has been slid over can be inferred.

[0059] like Figure 8 As shown, for the performance test of the device in recognizing texture, the sensor based on the single-sided micro-tactile structure disclosed in this embodiment calculates the texture width through the time difference when the response current is greater than the current when the sensor is insulated and the speed of the displacement stage. The response currents of the sensor based on the single-sided micro-tactile structure disclosed in this embodiment and the common symmetrical internal microstructure sensor are shown in Figures (a) and (c), respectively. The speed of the displacement stage is 944.78um / s. It can be clearly seen in Figure (a) that the time difference between the currents generated by the sensor sliding over the same texture twice is within 0.0025 seconds. Combined with the speed of the displacement stage, the deviation of the two detection results is within 2.37um. The time difference of the current between textures with a width difference of 50um is about 0.053 seconds. Combined with the speed of the displacement stage, the texture width difference detected by the sensor is about 50.07um. In Figure (c), the time difference of the current generated by the sensor sliding over the same texture twice is more than 0.02 seconds. Combined with the speed of the displacement stage, the deviation of the two detection results is more than 18.90um. Except for the texture with a width of 100um, the time difference of the current of the textures with other widths has obvious overlap. The summary data of 10 measurements of the sensor based on the single-sided internal micro-tactile structure disclosed in this embodiment and the common symmetrical internal micro-structure sensor are shown in Figures (b) and (d), respectively. The sensor based on the single-sided internal micro-tactile structure disclosed in this embodiment can clearly identify textures with widths of 100um, 150um, 200um and 250um, and the volatility of the 10 detection data of each texture is very small, while the common symmetrical internal micro-structure sensor not only cannot identify textures with widths of 100um, 150um, 200um and 250um, but also the volatility of the 10 detection data of each texture is very large.

[0060] Furthermore, the thickness of the first flexible substrate and the second flexible substrate is 6-50 μm.

[0061] Furthermore, the first sensing structure layer 7 and the second sensing structure layer 8 have a thickness of 200-400 μm, wherein the second sensing structure layer 8 is provided with a contact sensing inner microstructure.

[0062] Furthermore, the PDMS substrate is made by curing a PDMS prepolymer obtained by mixing a polydimethylsiloxane elastomer with a curing agent.

[0063] The PDMS substrate does not have conductive properties to prevent leakage in the circuit of the sensor.

[0064] Furthermore, the first sensing structure layer and the second sensing structure layer are made of GPC ink obtained by mixing PDMS prepolymer and graphene powder, and the mass proportion of graphene powder in the GPC ink is 15-45%.

[0065] Furthermore, the PDMS prepolymer is prepared by mixing a polydimethylsiloxane elastomer with a curing agent, and the mass ratio of the polydimethylsiloxane elastomer to the curing agent is 5:1.

[0066] The method for preparing a sensor based on a single-sided internal micro-tactile structure and the sensor based on a single-sided internal micro-tactile structure prepared by the method can effectively avoid the problem of unstable sensor piezoresistive characteristics caused by the misalignment of the protruding structure of the interlocking internal microstructure of the sensing structure layer of the traditional tactile sensor, and the use of sandpaper with a frosted surface to prepare the single-sided internal micro-tactile structure significantly reduces the preparation cost of the sensing structure layer in the sensor, simplifies the preparation process, and can be used for large-area sensor preparation arrays; the method for preparing a sensor based on a single-sided internal micro-tactile structure uses sandpaper as a template, and uses the tactile sensing layer structure prepared by the micro-nano hierarchical structure of sandpaper to make the sensor The device has high tactile sensing sensitivity. Compared with traditional tactile sensors that require photolithography of complex structure film-making templates, this method only requires simple arc-shaped pit film-making steel plates and sandpaper, and uses a press-bonded film-making method to produce a structural layer for tactile sensing. The production method is simple and low-cost. Compared with the interlocking internal microstructures in traditional tactile sensors, the sensor based on the single-sided internal micro-tactile structure has a PDMS substrate with a raised structure. The sensor prepared by this method uses a single-sided internal micro-tactile structure layer, so that when the sensor is used to identify texture three-dimensional information, the difference in piezoresistive characteristics caused by the misalignment of the interlocking internal microstructure can be avoided, thereby improving the accuracy and stability of identifying texture three-dimensional information.

[0067] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for preparing a sensor based on a single-plane micro-tactile structure, characterized in that: The following steps are involved: Mixing a polydimethylsiloxane elastomer with a curing agent to obtain a PDMS prepolymer, adding graphene powder to the PDMS prepolymer and stirring to obtain a GPC ink; The PDMS prepolymer layer is spin-coated on the surface of one side of the film-forming steel plate provided with the arc-shaped pit, the PET layer is pressed on the PDMS prepolymer layer, and the film-forming steel plate is peeled off to obtain a PDMS substrate, wherein a strip-shaped convex structure corresponding to the arc-shaped pit is formed on the upper surface of the PDMS substrate; The GPC ink is evenly applied and poured on the upper surface of the ITO-PET layer to form a GPC layer, one side surface of another PET layer is pressed on the GPC layer, and after heating the poured GPC layer, the PET layer is peeled off to obtain a first sensing structure layer; The GPC ink is evenly applied and poured on the upper surface of the ITO-PET layer to form a GPC layer, the frosted surface of sandpaper is pressed on the GPC layer, the GPC layer formed by the pouring is heated, and then the sandpaper is peeled off to obtain a second sensing structure layer, and a contact sensing internal microstructure corresponding to the sandpaper is formed on one side surface of the second sensing structure layer; The first sensing structure layer, the second sensing structure layer and the PDMS substrate are stacked sequentially from top to bottom to form a composite sensing structure layer; the composite sensing structure layer is used for contact sensing; The PI tape is attached to the edge of the composite sensing structure layer to encapsulate and fix the layer to obtain the sensor.

2. The method for preparing a sensor based on a single-plane micro-tactile structure according to claim 1, characterized in that: Before peeling off the film-forming steel plate to obtain the PDMS substrate, the method further comprises: curing the PDMS prepolymer layer in a temperature environment of 80-100° C.

3. The method for preparing a sensor based on a single-plane micro-tactile structure according to claim 1, characterized in that: Before pouring the GPC ink on the upper surface of the ITO-PET layer and evenly spreading it to form the GPC layer, the method further includes: attaching a PI tape to the side edge of the ITO-PET layer to measure the formation height of the GPC layer.

4. The method for preparing a sensor based on a single-plane micro-tactile structure according to claim 1, characterized in that: The height of the protruding structure is 1-3 mm, and the width of the protruding structure is 2-6 mm.

5. The method for preparing a sensor based on a single-plane micro-tactile structure according to claim 1, characterized in that: The mesh number of the sandpaper is 60-240.

6. A sensor based on a single-plane micro-tactile structure, characterized in that: The sensor is manufactured by the preparation method of the sensor based on the single-sided micro-tactile structure as described in any one of claims 1 to 5, the composite sensing structure layer includes the PDMS substrate, the first sensing structure layer and the second sensing structure layer, a flexible insulating layer is arranged on the side edges of the first sensing structure layer and the second sensing structure layer, a first flexible substrate and a first flexible electrode are formed on the surface of the second sensing structure layer facing the PDMS substrate, and a second flexible electrode and a second flexible substrate are formed on the surface of the first sensing structure layer away from the second sensing structure layer; the sensor also includes a PI tape encapsulated and fixed to the edge of the composite sensing structure layer.

7. The sensor based on the single-plane micro-tactile structure according to claim 6, characterized in that: The thickness of the first flexible substrate and the second flexible substrate is 6-50 μm.

8. The sensor based on a single-plane micro-tactile structure according to claim 6, characterized in that: The thickness of the first sensing structure layer and the second sensing structure layer is 200-400 μm, wherein the second sensing structure layer is provided with a contact sensing inner microstructure.

9. The sensor based on a single-plane micro-tactile structure according to claim 6, characterized in that: The PDMS substrate is prepared by curing a PDMS prepolymer obtained by mixing a polydimethylsiloxane elastomer with a curing agent.

10. The sensor based on a single-plane micro-tactile structure according to claim 6, characterized in that: The first sensing structure layer and the second sensing structure layer are made of GPC ink obtained by mixing PDMS prepolymer and graphene powder, and the mass proportion of the graphene powder in the GPC ink is 15-45%.

11. The sensor based on a single-plane micro-tactile structure according to claim 10, characterized in that: The PDMS prepolymer is prepared by mixing a polydimethylsiloxane elastomer with a curing agent, and the mass ratio of the polydimethylsiloxane elastomer to the curing agent is 5:1.

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