Flexible tactile sensor and method of manufacturing the same

Abstract

The present application relates to flexible tactile sensor and its manufacturing method. The first flexible tactile sensor includes flexible substrate, temperature sensing layer, insulation layer, stress layer, lower structure layer, strain gauge layer, wire layer, upper structure layer and encapsulation layer; the upper structure layer and the lower structure layer wrap the wire layer and the strain gauge layer to form four-layer structure; the stress layer is located below the lower structure layer or above the upper structure layer, and drives the four-layer structure to curl to form three-dimensional structure; the encapsulation layer wraps the planar structure and the three-dimensional structure and is connected to the flexible substrate. In the second flexible tactile sensor, the upper structure layer and the lower structure layer wrap the row selection wire layer, the insulation layer, the strain gauge layer and the column selection wire layer to form six-layer structure, and the stress layer drives the six-layer structure to curl to form three-dimensional structure. The present application is fully compatible with the existing microelectronic processing technology, allows low-cost, batch parallel production, and realizes the flexible tactile sensor with customizable spatial density and array shape.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sensors and electronic skin, in particular to a flexible tactile sensor and a manufacturing method thereof. BACKGROUND

[0002] At present, the field of robots is developing rapidly and plays an important role in the fields of industrial automation, human-computer interaction, etc. The diversification of robot movement and perception ability is a key target pursued by researchers. Tactile is an important way for humans to perceive and interact with the external environment, which can help humans obtain the physical characteristics of the external environment. Giving robots the same tactile perception ability as humans is crucial for information acquisition and processing of robots in application scenarios such as fine operation, assisted medical treatment, and human-computer interaction. Small, accurate, and customizable tactile sensors provide a basis for expanding the perception ability of robots and improving the control accuracy of robots.

[0003] At present, the existing tactile sensor has at least the following shortcomings: first, tactile information usually includes three components of normal pressure, shear force and temperature, and the existing tactile sensor usually has the ability to perceive one or two parameters, but does not have the ability to decouple the three. Second, the existing tactile sensor is usually difficult to integrate with mature circuit technology (such as FPC, commercial chip, etc.), limiting its data processing and convenience in practical application. Finally, the existing tactile sensor can usually only realize single-point tactile perception, and it is difficult to realize large-area tactile monitoring in a customizable array shape. SUMMARY

[0004] The present application provides a flexible tactile sensor and a manufacturing method thereof to overcome the shortcomings of the prior art.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] The first flexible tactile sensor comprises a flexible substrate, a temperature sensing layer, an insulating layer, a stress layer, a lower structural layer, a strain gauge layer, a wire layer, an upper structural layer and a packaging layer; wherein the flexible substrate, the temperature sensing layer and the insulating layer are arranged in order from bottom to top, and the lower structural layer, the strain gauge layer, the wire layer and the upper structural layer are arranged in order from bottom to top; the upper structural layer and the lower structural layer wrap the wire layer and the strain gauge layer to form a four-layer structure; the stress layer is located below the lower structural layer or above the upper structural layer, and the stress layer drives the four-layer structure to curl to form a three-dimensional structure; the flexible substrate, the temperature sensing layer and the insulating layer are planar structures and are located directly below the three-dimensional structure; the insulating layer is used to separate the temperature sensing layer and other conductive components to improve their stability; the packaging layer wraps the planar structure and the three-dimensional structure and is connected to the flexible substrate.

[0007] The second flexible tactile sensor comprises a flexible substrate, a stress layer, a lower structural layer, a row selection wire layer, an insulating layer, a strain gauge layer, a column selection wire layer, an upper structural layer, and a packaging layer; the lower structural layer, the row selection wire layer, the insulating layer, the strain gauge layer, the column selection wire layer, and the upper structural layer are arranged in sequence from bottom to top, and the upper structural layer and the lower structural layer wrap the row selection wire layer, the insulating layer, the strain gauge layer, and the column selection wire layer to form a six-layer structure; the stress layer is located below the lower structural layer or above the upper structural layer, and the stress layer drives the six-layer structure to curl to form a three-dimensional structure; the insulating layer has a through hole for connecting the row selection wire layer and the column selection wire layer at a specific position; and the packaging layer wraps the three-dimensional structure and is connected to the flexible substrate.

[0008] The second tactile sensor described above can also have a temperature sensing layer, i.e., a temperature sensing layer is added between the flexible substrate and the stress layer and the insulating layer.

[0009] Preferably, the materials of the flexible substrate, the insulating layer, and the structural layer (the upper structural layer and the lower structural layer) are PI (Polyimide, polyimide), or PET (Polyethylene terephthalate, polyethylene terephthalate), or PEN (Polyethylene naphthalate two formic acid glycol ester, polyethylene naphthalate), or PDMS (Polydimethylsiloxane, polydimethylsiloxane), or PU (Polyurethane, polyurethane), or poly-p-xylylene, or epoxy resin, or PEDOT:PSS (Poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonate), poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)), or other flexible and biocompatible insulating materials.

[0010] Preferably, the material of the stress layer is SiO2, or Si3N4, or polycrystalline / amorphous silicon, or other materials that generate intrinsic stress in the process of thin film preparation. The stress layer can be located below the lower structural layer to drive the four-layer structure to curl through compressive stress, or can be located above the upper structural layer to drive the four-layer structure to curl through tensile stress.

[0011] Preferably, the materials of the temperature sensing layer, the strain gauge layer, and the wire layer are metal materials such as Au, Cu, and Al, or alloy materials such as CrNi and CuNi.

[0012] Preferably, the material of the encapsulation layer is a silicone-based material such as PDMS, Ecoflex, prepared by a reverse mold encapsulation process using a mold prepared by 3D printing or CNC machining, and the shape of the reverse mold encapsulation is hemispherical, or conical, or pyramid-shaped, or cuboid-shaped, etc., to form a hemispherical encapsulation layer, or a conical encapsulation layer, or a pyramid-shaped encapsulation layer, or a cuboid-shaped encapsulation layer, etc.

[0013] Preferably, the temperature sensing layer and the wire layer are provided with electrodes connected to an external circuit, and the functions of the external circuit include crosstalk suppression, channel selection, signal processing, analog-to-digital conversion, wireless data transmission, energy supply, etc. The sensor can be attached or soldered to a flexible circuit board like a chip and connected to an external circuit through a flexible flat cable to ensure the flexibility of the sensor part.

[0014] Preferably, the spatial density of the three-dimensional structure can be designed according to the capability of micro-nano processing, and has the potential to exceed the density of human finger tactile receptors (> 140 / cm 2 ).

[0015] The first method for manufacturing a flexible tactile sensor comprises the following steps:

[0016] Preparation of a flexible substrate on a substrate;

[0017] Sequential preparation of a temperature sensing layer, an insulating layer, a sacrificial layer, a stress layer, a lower structure layer, a strain gauge layer, a wire layer, and an upper structure layer on the flexible substrate;

[0018] Wet etching of the sacrificial layer to cause the stress layer to drive the lower structure layer, the strain gauge layer, the wire layer, and the upper structure layer supported thereby to curl and form a three-dimensional structure;

[0019] Preparation of an encapsulation layer on the three-dimensional structure;

[0020] Removal of the flexible substrate from the substrate to obtain a flexible tactile sensor.

[0021] The second method for manufacturing a flexible tactile sensor comprises the following steps:

[0022] Preparation of a flexible substrate on a substrate;

[0023] Sequential preparation of a sacrificial layer, a stress layer, a lower structure layer, a row selection wire layer, an insulating layer, a strain gauge layer, a column selection wire layer, and an upper structure layer on the flexible substrate;

[0024] Wet etching of the sacrificial layer to cause the stress layer to drive the lower structure layer, the row selection wire layer, the insulating layer, the strain gauge layer, the column selection wire layer, and the upper structure layer supported thereby to curl and form a three-dimensional structure;

[0025] The encapsulation layer is prepared on a three-dimensional structure;

[0026] The flexible substrate is peeled off from the base to obtain the flexible tactile sensor.

[0027] Preferably, the flexible substrate, the lower structural layer, the insulating layer and the upper structural layer are prepared by spin coating.

[0028] Preferably, the sacrificial layer, the stress layer, the wire layer, the row selection wire layer, the column selection wire layer and the strain gauge layer are prepared by physical vapor deposition (PVD) or chemical vapor deposition (CVD).

[0029] Preferably, the material of the sacrificial layer is a metal-based material such as Al, Mg or Zn, or a polymer-based material such as PMMA (Polymethyl methacrylate) or photoresist.

[0030] Preferably, the preparation process includes a thin film patterning process not mentioned above, and the patterning method includes photolithography, stripping or etching.

[0031] The first flexible tactile sensor provided by the present application has the ability to perceive multi-modal tactile information such as normal pressure, shear force and temperature, and is suitable for application scenarios such as pressure sore prevention and bionic tactile sensing. The second flexible tactile sensor adopts an array form and mainly perceives normal pressure, has a large spatial density and high spatial resolution, and is suitable for application scenarios such as fine operation of robots and human-computer interaction.

[0032] As can be seen from the technical solutions provided by the present application, the tactile sensor processing method proposed by the present application is fully compatible with existing microelectronic processing technology, allowing low-cost, batch parallel production. Moreover, the performance and spatial density of the sensor can be parameterized according to needs. The tactile sensor is flexible and small in size, and can be pasted or soldered on a flexible circuit board of different shapes for use, integrated with commercial chips and circuits. Therefore, the present application truly realizes a flexible tactile sensor with a spatial density and array shape that can be customized as needed.

[0033] Additional aspects and advantages of the application will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0035] Figure 1 Structure diagram of the first flexible tactile sensor provided by the embodiment of the present application.

[0036] Figure 2 The first flexible tactile sensor provided by the embodiment of the present application. Figure 1 Shape diagram of each layer of the first flexible tactile sensor, wherein (a) is the shape of the flexible substrate, (b) is the shape of the temperature sensing layer, (c) is the shape of the insulating layer, (d) is the shape of the sacrificial layer, (e) is the shape of the stress layer, (f) is the shape of the lower structural layer, (g) is the shape of the wire layer, (h) is the shape of the strain gauge layer, and (i) is the shape of the upper structural layer.

[0037] Figure 3 Microscopic view of the three-dimensional structure of the first flexible tactile sensor provided by the embodiment of the present application.

[0038] Figure 4 Position diagram of the strain gauges before and after the three-dimensional structure of the first flexible tactile sensor provided by the embodiment of the present application is warped, wherein (a) is before the three-dimensional structure is warped, and (b) is after the three-dimensional structure is warped.

[0039] Figure 5 Working principle diagram of the first flexible tactile sensor provided by the embodiment of the present application.

[0040] Figure 6 Response of the four three-dimensional strain gauges and the temperature sensing module in the first flexible tactile sensor provided by the embodiment of the present application under normal pressure, shear force and temperature excitation.

[0041] Figure 7 Structure diagram of the second flexible tactile sensor provided by the embodiment of the present application.

[0042] Figure 8 Shape diagram of each layer of the second flexible tactile sensor provided by the embodiment of the present application, wherein (a) is the shape of the flexible substrate, (b) is the shape of the sacrificial layer, (c) is the shape of the stress layer, (d) is the shape of the lower structural layer, (e) is the shape of the row selection wire layer, (f) is the shape of the insulating layer, (g) is the shape of the column selection wire layer, (h) is the shape of the strain gauge layer, and (i) is the shape of the upper structural layer.

[0043] Figure 9 Microscopic view of the three-dimensional structure of the second flexible tactile sensor provided by the embodiment of the present application.

[0044] Figure 10 Position diagram of the strain gauges before and after the three-dimensional structure of the second flexible tactile sensor provided by the embodiment of the present application is warped, wherein (a) is before the three-dimensional structure is warped, and (b) is after the three-dimensional structure is warped.

[0045] Figure 11 The second flexible tactile sensor provided by the embodiment of the present application responds to different shapes of external pressure.

[0046] Figure 12 The photo of the arrayed flexible tactile sensor provided by the embodiment of the present application. DETAILED DESCRIPTION

[0047] The embodiments of the present application are described in detail below with reference to the accompanying drawings, in which the same or similar components have the same or similar reference numerals throughout. The embodiments described below are exemplary and are used only for the purpose of explaining the present application, and should not be construed as limiting the present application.

[0048] Those skilled in the art can understand that the singular forms "a," "an," and "the" as used herein include plural references unless otherwise stated. It should be further understood that the use of the term "include" in the specification of the present application means that the stated features, integers, steps, operations, elements, and / or components are present, but not excluding the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there can be an intermediate element. In addition, "connected" or "coupled" as used herein can include wireless connection or coupling. The term "and / or" as used herein includes any one or more of the associated listed items, and all combinations of the associated listed items.

[0049] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as that understood by a person of ordinary skill in the art to which the present application belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have meanings consistent with those in the context of the prior art, and should not be interpreted with idealized or overly formal meanings unless defined as such.

[0050] For the purpose of facilitating the understanding of the embodiments of the present application, further explanation and description will be made below with reference to the accompanying drawings, taking specific embodiments as examples, and the embodiments do not constitute a limitation on the embodiments of the present application.

[0051] Embodiment One

[0052] Figure 1A structural diagram of a first flexible tactile sensor according to an embodiment of the present application is provided. The flexible tactile sensor includes a PI flexible substrate, a Cr / Au temperature sensing layer, a PI insulating layer, an Al sacrificial layer, a SiO2 stress layer, a PI lower structural layer, a NiCr strain gauge layer, a Cr / Au wire layer, a PI upper structural layer, and a PDMS square packaging layer. The lower structural layer and the upper structural layer wrap the wire layer and the strain gauge layer to form a four-layer structure. The stress layer supports the four-layer structure, and after the sacrificial layer is etched away, the stress layer curls due to intrinsic stress, causing the lower structural layer, the strain gauge layer, the wire layer, and the upper structural layer to also curl, forming a three-dimensional structure. The shape of each layer of the first flexible tactile sensor is as shown in Figure 2

[0053] The flexible tactile sensor of the present application is processed based on a micro-nano processing technology, and can achieve excellent consistency, stability, and yield. The physical properties of the thin film prepared in the processing process are excellent, and the size, stress, and thickness of the thin film can be flexibly controlled by adjusting various parameters, which makes the prepared sensor have excellent performance, diverse structure, and good consistency.

[0054] The specific processing method of the flexible tactile sensor of the present application includes the following steps:

[0055] 1) Start with a clean high-conductivity silicon-based substrate, and use a spin coater to spin a layer of PI thin film as a flexible substrate.

[0056] 2) Use a photoetching machine to perform negative photoetching, and then use a magnetron sputtering film coater to continuously sputter a layer of Cr thin film and a layer of Au thin film as a temperature sensing layer, and then perform patterning on the temperature sensing layer by a peeling process.

[0057] 3) Use a spin coater to spin a layer of PI thin film as an insulating layer.

[0058] 4) Use a magnetron sputtering film coater to sputter a layer of Al thin film as a sacrificial layer and a layer of SiO2 thin film as a stress layer. The intrinsic stress in the stress layer comes from the atomic shot peening effect in the magnetron sputtering process. Use a photoetching machine to perform positive photoetching, and use a reactive ion etching machine to pattern the stress layer according to the shape of the strain gauge arrangement in the strain gauge layer (for example, a cross shape in Figure 2 , which can also be other shapes). Use a photoetching machine to perform positive photoetching, and use a wet etching method to pattern the sacrificial layer. The stress of the thin film depends on the control of the magnetron sputtering parameters.

[0059] 5) Use a spin coater to spin a layer of PI thin film as a lower structural layer, and the three-dimensional structure of the sensor depends on the size, thickness, and size of the thin film stress and the structural layer.

[0060] ​6) Using a photoetching machine to perform negative photoetching, using a magnetron sputtering coating machine to sputter a thin film of NiCr alloy as a strain gauge layer, and using a stripping process to pattern the strain gauge layer.

[0061] 7) Using a photoetching machine to perform negative photoetching, using a magnetron sputtering coating machine to continuously sputter a thin film of Cr and a thin film of Au as a wire layer, and using a stripping process to pattern the wire layer.

[0062] 8) Using a spin coater to spin a thin film of PI as an upper structure layer, using a magnetron sputtering coating machine to sputter a layer of Al as a barrier layer, using a photoetching machine to perform positive photoetching, using a wet etching process to pattern the barrier layer, and using a reactive ion etching machine to pattern the upper structure layer and the lower structure layer.

[0063] 9) Using a wet etching process to remove the sacrificial layer and the barrier layer, due to the presence of intrinsic compressive stress in the stress layer, the lower structure layer, the strain gauge layer, the wire layer, and the upper structure layer are curled to form a three-dimensional structure.

[0064] 10) Using a CNC lathe to process an aluminum alloy square hollow mold, aligning the mold hollow part with the three-dimensional structure, pouring the uncured PDMS into the mold, removing the mold after the PDMS is cured, and obtaining a square package.

[0065] 11) Electrolyzing the silicon wafer with a NaCl solution, and the flexible substrate falls off the silicon wafer, and the flexible tactile sensor is completed.

[0066] In this embodiment, the strain gauge layer uses four strain gauges, and four curled three-dimensional structures are wrapped in one flexible tactile sensor. Figure 3 For the three-dimensional structure after the sacrificial layer is etched. The four strain gauges are arranged in a cross shape, and the temperature sensing module is located directly below the three-dimensional strain gauge through a layer of PI insulation. As Figure 4 shown, the four strain gauges have a certain distance in space, and when the sacrificial layer is etched, the four strain gauges are independently curled to form four three-dimensional structures. The heights of the four three-dimensional structures after curling are the same, the shapes are the same, and the positions in the packaging layer are symmetrical.

[0067] Strain gauges are commonly used in microfabrication and have excellent performance stability. When subjected to external force, they will experience strain and change in resistance. Referring to Figure 5 , in the initial state, the four three-dimensional structures have the same shape. When the packaging layer is subjected to normal pressure, the four strain gauges are subjected to the same pressure and experience tensile strain, and the resistance increases. Figure 6 The resistance of the four strain gauges increases linearly in response to normal pressure on the packaging layer. When the packaging layer is subjected to normal pressure, the temperature sensing layer has a planar structure, and its strain and resistance change can be ignored. Figure 6The response of the three-dimensional strain gauges and the planar temperature sensing module in (b) of FIG. 1 to the normal pressure on the encapsulation layer. When the encapsulation layer is subjected to horizontal shear force, the two three-dimensional strain gauges perpendicular to the shear force direction have negligible strain and resistance change, one of the two strain gauges parallel to the shear force direction is subjected to compressive strain and the resistance decreases, and the other is subjected to tensile strain and the resistance increases. Figure 6 The resistance response of the four strain gauges in (c) of FIG. 1 to the horizontal shear force on the encapsulation layer. When the temperature changes, the resistance of the planar temperature sensing layer and the three-dimensional strain gauges will change. Figure 6 The resistance response of the planar temperature sensing layer and the three-dimensional strain gauges in (d) of FIG. 1 to the change in ambient temperature. The resistance of the temperature sensing layer is only related to the change in temperature and is not affected by the normal pressure and the horizontal shear force, so it can be used as an accurate temperature sensing unit and is less disturbed by the change in temperature on the resistance of the three-dimensional strain gauges.

[0068] The external excitation acting on the flexible tactile sensor is divided into temperature excitation and mechanical excitation, and the temperature excitation and the mechanical excitation can be considered as linear superposition. The mechanical excitation can be further divided into normal pressure and horizontal shear force, and the two can also be considered as linear superposition. Therefore, there are four unknowns in the multi-parameter decoupling, including temperature, z-axis direction normal pressure amplitude, x-axis direction shear force amplitude and y-axis direction horizontal shear force amplitude. There are five knowns, including the resistance changes of the four three-dimensional strain gauges and the resistance change of the temperature sensing layer. Since the unknowns can be considered as linear superposition, a linear equation set containing four unknowns can be listed. Using the five knowns, the solution of the linear equation set can be easily solved, and the multi-parameter decoupling is realized.

[0069] Embodiment Two

[0070] Figure 7 The structure schematic diagram of the second flexible tactile sensor provided in this embodiment. The difference between this embodiment and the first embodiment is that the second flexible tactile sensor contains more three-dimensional strain gauges, which are arranged in the same direction and form a three-dimensional strain gauge array with high spatial density. The second flexible tactile sensor includes a PI flexible substrate, an Al sacrificial layer, a SiO2 stress layer, a PI lower structural layer, a Cr / Au row selection wire layer, a PI insulating layer, a NiCr strain gauge layer, a Cr / Au column selection wire layer, a PI upper structural layer and a PDMS square encapsulation layer. The lower structural layer and the upper structural layer wrap the row selection wire layer, the insulating layer, the strain gauge layer and the column selection wire layer to form a six-layer structure. The stress layer supports the six-layer structure, and after the sacrificial layer is etched away, the stress layer curls due to the intrinsic stress inside, driving the six-layer structure to curl and form a three-dimensional structure. The shape of each layer of the second flexible tactile sensor is shown in FIG. 2. Figure 8

[0071] ​The specific processing method of the second flexible tactile sensor of the present application comprises the following steps:

[0072] 1) Starting from a clean high-conductive silicon substrate, a PI film is spin-coated as a flexible substrate using a spin coater.

[0073] 2) An Al film is sputtered as a sacrificial layer and a SiO2 film is sputtered as a stress layer using a magnetron sputtering machine. The intrinsic stress in the stress layer comes from the atomic shot effect in the magnetron sputtering process. Positive photoresist lithography is performed using a photoetching machine, and the stress layer is patterned according to the shape of the strain gauge arrangement in the strain gauge layer using a reactive ion etching machine. The sacrificial layer is patterned using positive photoresist lithography and a wet etching method. The stress of the thin film depends on the control of the magnetron sputtering parameters.

[0074] 3) A PI film is spin-coated as a lower structural layer using a spin coater. The three-dimensional structure of the sensor depends on the size of the film stress, the thickness and size of the structural layer. Negative photoresist lithography is performed using a photoetching machine, and a Cr film and an Au film are continuously sputtered as row selection wire layers using a magnetron sputtering machine. The row selection wire layers are patterned by a peeling process.

[0075] 4) A PI film is spin-coated as an insulating layer using a spin coater, an Al film is sputtered as a barrier layer using a magnetron sputtering machine, positive photoresist lithography is performed using a photoetching machine, the Al barrier layer is patterned using a wet etching method, and the insulating layer is patterned using a reactive ion etching machine to form a through hole.

[0076] 5) Negative photoresist lithography is performed using a photoetching machine, and a NiCr alloy film is sputtered as a strain gauge layer using a magnetron sputtering machine. The strain gauge layer is patterned by a peeling process.

[0077] 6) Negative photoresist lithography is performed using a photoetching machine, and a Cr film and an Au film are continuously sputtered as column selection wire layers using a magnetron sputtering machine. The column selection wire layers are patterned by a peeling process.

[0078] 7) A PI film is spin-coated as an upper structural layer using a spin coater. An Al film is sputtered as a barrier layer using a magnetron sputtering machine, positive photoresist lithography is performed using a photoetching machine, the barrier layer is patterned by a wet etching method, and the upper structural layer and the lower structural layer are patterned using a reactive ion etching machine.

[0079] 8) The sacrificial layer and the barrier layer are etched away using a wet etching method. Due to the existence of intrinsic compressive stress in the stress layer, the lower structural layer, the row selection wire layer, the insulating layer, the strain gauge layer, the column selection wire layer and the upper structural layer are curled to form a three-dimensional structure.

[0080] 9) Using CNC lathe to process aluminum alloy square hollow mold, aligning the mold hollow part with the three-dimensional structure, pouring the uncured PDMS into the mold, and removing the mold after the PDMS is cured to obtain a square package.

[0081] 10) Electrolyzing the silicon wafer with NaCl solution, and the flexible substrate is separated from the silicon wafer, and the flexible tactile sensor is prepared.

[0082] Figure 9 The three-dimensional structure of the second flexible tactile sensor provided in this embodiment after the sacrifice layer is corroded. As shown in Figure 10 , there are forty strain gauges in the encapsulation layer, which are spaced apart from each other. After the sacrifice layer is corroded, each strain gauge is independently curled to form a three-dimensional structure. The height of each three-dimensional structure after curling is the same, and the shape is the same, but the position in the encapsulation layer is asymmetric. Among them, the minimum line width of the strain gauge is 12 μm, and the spatial arrangement density is 40 / cm 2 . The 40 three-dimensional strain gauges form a four-row and ten-column arrangement, and are connected through four row selection electrodes and ten column selection electrodes. Further, if the minimum line width of the strain gauge layer is reduced to 4.8 μm, a three-dimensional strain gauge spatial density of 360 / cm 2 can be achieved. The second flexible tactile sensor provided in this embodiment has the ability to characterize the normal pressure distribution in a small area. Its principle is similar to that of the first flexible tactile sensor. When the encapsulation layer is subjected to normal pressure, the arrayed three-dimensional strain gauges are strained to produce resistance changes. Since the three-dimensional strain gauges are distributed throughout the encapsulation area, the position relative to the normal pressure is asymmetric, so the three-dimensional strain gauges at different positions respond differently when subjected to normal pressure. Figure 11 is the resistance response of the second flexible tactile sensor provided in this embodiment when subjected to normal pressure of different shapes.

[0083] In this embodiment, there are forty strain gauges in the encapsulation layer, and the number of strain gauges can be adjusted as needed in other embodiments.

[0084] Embodiment Three

[0085] Since the processing technology in Embodiment One and Embodiment Two can be realized in parallel for mass production, multiple high-consistency flexible tactile sensors can be prepared on the same silicon wafer substrate. Through the encapsulation and substrate peeling methods described in the above embodiments, a tactile sensor on a flexible substrate can be obtained. After dicing the tactile sensor on a large-area flexible substrate, a small-size, individually usable flexible tactile sensor can be obtained. By soldering or bonding these flexible tactile sensors to a flexible circuit board like a commercial chip, a Figure 12The flexible tactile sensor array is shown. With the cooperation of the back-end circuit design, a small, wireless tactile information sensing system can be realized. According to different application requirements, the flexible sensor can be welded or bonded on a flexible circuit board of any shape for use, and can be integrated with mature circuit technologies such as commercial chips.

[0086] In summary, compared with the design and implementation scheme of the traditional tactile sensor, the flexible tactile sensor and the manufacturing method thereof have the characteristics of high yield and high consistency by using the parallel microelectronic processing technology, can realize array and batch preparation, have the ability of multi-parameter decoupling and array tactile information distribution sensing, and can be easily integrated on the existing circuit to meet the flexible requirements of different application scenarios. The flexible tactile sensor prepared by the present application is small in size, simple in operation, and truly realizes convenient, fast, wearable / skin tactile sensing.

[0087] The manufacturing method proposed by the present application adopts the basic process flow in the laboratory, does not involve high-cost processing technology, and has the advantages of simple preparation process, low cost, short production cycle and the possibility of large-scale batch production.

[0088] Those skilled in the art can understand that the drawings are only schematic diagrams of an embodiment, and the modules or processes in the drawings are not necessarily required to implement the present application.

[0089] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other, and each embodiment mainly describes the difference from other embodiments. Especially, since the device or system embodiment is basically similar to the method embodiment, it is described more simply, and the related parts can be referred to the part of the method embodiment. The device and system embodiments described above are only schematic, and the units described as separate components can be or can not be physically separated, and the components displayed as units can be or can not be physical units, that is, they can be located in one place, or can be distributed on multiple network units. According to the actual needs, part or all of the modules can be selected to achieve the purpose of the embodiment scheme. Those skilled in the art can understand and implement without creative labor.

[0090] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A flexible tactile sensor, characterized by, The flexible substrate, the temperature sensing layer, and the insulation layer are in a planar structure and are located directly below the three-dimensional structure; and the encapsulation layer wraps the planar structure and the three-dimensional structure and is connected to the flexible substrate. The flexible substrate, the temperature sensing layer, and the insulation layer are in a planar structure and are located directly below the three-dimensional structure; and the encapsulation layer wraps the planar structure and the three-dimensional structure and is connected to the flexible substrate.

2. A flexible tactile sensor, characterized by, The flexible substrate, the temperature sensing layer, and the insulation layer are in a planar structure and are located directly below the three-dimensional structure; and the encapsulation layer wraps the planar structure and the three-dimensional structure and is connected to the flexible substrate.

3. The flexible tactile sensor according to claim 1 or 2, wherein, The material of the flexible substrate, the insulation layer, the upper structural layer, and the lower structural layer is an insulating material with flexibility and biocompatibility.

4. The flexible tactile sensor of claim 3, wherein, The material of the flexible substrate, the insulation layer, the upper structural layer, and the lower structural layer is one of the following: polyimide, polyethylene terephthalate, polyethylene naphthalate, polydimethylsiloxane, polyurethane, parylene, epoxy resin, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid.

5. The flexible tactile sensor according to claim 1 or 2, wherein The material of the stress layer is SiO2, or Si3N4, or polysilicon, or amorphous silicon, or other materials that generate intrinsic stress in the thin film preparation process.

6. The flexible tactile sensor of claim 1 or 2, wherein, The material of the temperature sensing layer, the strain gauge layer, and the wire layer is a metal material or an alloy material.

7. The flexible tactile sensor according to claim 1 or 2, wherein The material of the encapsulation layer is a silica gel material, which is prepared by inverse molding encapsulation; the mold used in the process of the inverse molding encapsulation is prepared by 3D printing or CNC machining, and the shape of the inverse molding encapsulation is hemispherical, conical, pyramidal, or cuboid, forming a hemispherical encapsulation layer, a conical encapsulation layer, a pyramidal encapsulation layer, or a cuboid encapsulation layer, respectively.

8. The flexible tactile sensor of claim 1 or 2, wherein, The temperature sensing layer and the wire layer have electrodes connected to an external circuit, and the functions of the external circuit include one of crosstalk suppression, channel selection, signal processing, analog-to-digital conversion, wireless data transmission, and energy supply.

9. A method of manufacturing the flexible tactile sensor of claim 1, wherein, The method comprises the following steps: Preparation of a flexible substrate on a substrate; Preparation of a temperature sensing layer, an insulation layer, a sacrificial layer, a stress layer, a lower structural layer, a strain gauge layer, a wire layer, and an upper structural layer on the flexible substrate in sequence; and Preparation of a temperature sensing layer, an insulation layer, a sacrificial layer, a stress layer, a lower structural layer, a strain gauge layer, a wire layer, and an upper structural layer on the flexible substrate in sequence; and The stress layer drives the lower structural layer, the strain gauge layer, the wire layer and the upper structural layer to curl to form a three-dimensional structure by wet etching away the sacrificial layer; A packaging layer is prepared on the three-dimensional structure; The flexible substrate is separated from the substrate to obtain the flexible tactile sensor.

10. A method of making the flexible tactile sensor of claim 2, wherein, The method comprises the following steps: A flexible substrate is prepared on a substrate; A sacrificial layer, a stress layer, a lower structural layer, a row selection wire layer, an insulating layer, a strain gauge layer, a column selection wire layer and an upper structural layer are sequentially prepared on the flexible substrate; The stress layer drives the lower structural layer, the row selection wire layer, the insulating layer, the strain gauge layer, the column selection wire layer and the upper structural layer to curl to form a three-dimensional structure by wet etching away the sacrificial layer; A packaging layer is prepared on the three-dimensional structure; The flexible substrate is separated from the substrate to obtain the flexible tactile sensor.

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