Electronic skin, its preparation methods and applications

Abstract

This application relates to the field of electronic skin technology, specifically to an electronic skin, its preparation method, and its application. The electronic skin includes a bioadhesive layer and a strain-sensing layer. The strain-sensing layer is located on at least one surface of the bioadhesive layer. The strain-sensing layer includes a first elastic layer, a conductive layer, and a second elastic layer sequentially stacked along its thickness direction. The second elastic layer is in contact with the bioadhesive layer, which includes polydimethylsiloxane, thereby effectively improving the electronic skin's resistance to water flow impact interference.

Description

Technical Field

[0001] This application relates to the field of electronic skin technology, and in particular to an electronic skin, its preparation method, and its application. Background Technology

[0002] Electronic skin, with its soft and stretchable properties, establishes a comfortable and stable interface with the skin, enabling continuous monitoring of biophysical, biochemical, and electrophysiological signals in the human body. Aquatic environments are unavoidable in daily life, such as swimming, bathing, and accidental splashes. In water-related scenarios, electronic skin devices need to maintain reliable and high-quality sensing performance to provide real-time health monitoring information during activities in water, and to provide timely warnings in dangerous situations such as underwater cramps, preventing sports injuries. Water-related scenarios can be divided into static water environments and dynamic water environments such as water impacts. Compared to dry environments in air, water environments present new challenges for wearable devices, such as potential sensor malfunctions and sensor detachment from the skin surface. Dynamic water impacts are more destructive than static water environments. Severe water flow can easily penetrate into the gaps at the device-skin interface, leading to detachment and sensor failure. Therefore, electronic skin devices suitable for various water environments urgently need research. Summary of the Invention

[0003] Based on this, this application provides an electronic skin that can withstand the impact of water flow, its preparation method, and its application.

[0004] A first aspect of this application provides an electronic skin comprising a bioadhesive layer and a strain-sensing layer, the strain-sensing layer being located on at least one surface of the bioadhesive layer, the strain-sensing layer comprising a first elastic layer, a conductive layer and a second elastic layer sequentially stacked along its thickness direction, the second elastic layer being in contact with the bioadhesive layer, the bioadhesive layer comprising polydimethylsiloxane.

[0005] In some embodiments, the soluble solids content of the bio-adhesive layer is 20%-70%.

[0006] In some embodiments, the soluble solids content of the bio-adhesive layer is 40%-70%.

[0007] In some embodiments, the thickness of the bio-adhesive layer is 10 μm-100 μm.

[0008] In some embodiments, the first elastic layer comprises a first elastomeric material, and the second elastic layer comprises a second elastomeric material.

[0009] In some embodiments, the thickness of the first elastic layer and the second elastic layer are each independently 1 μm-1000 μm; optionally, they are 1 μm-100 μm.

[0010] In some embodiments, the first elastomer material and the second elastomer material each independently comprise one or more of polydimethylsiloxane, platinum-catalyzed silica gel, polyurethane, styrene-butadiene-styrene block copolymer, and styrene-ethylene-butene-styrene block copolymer.

[0011] In some embodiments, the conductive layer comprises a carbon nanomaterial.

[0012] In some embodiments, the thickness of the conductive layer is 10 nm to 500 nm.

[0013] In some embodiments, the nanomaterial includes one or more of carbon spheres, carbon nanotubes, and graphene.

[0014] A second aspect of this application provides a method for preparing the electronic skin described in the first aspect of this application, comprising the following steps:

[0015] Prepare the first elastic layer;

[0016] The conductive layer is prepared on the first elastic layer;

[0017] The second elastic layer is prepared on the conductive layer;

[0018] The bio-adhesive layer is prepared on the second elastic layer.

[0019] In some embodiments, the step of preparing the bioadhesive layer on the second elastic layer includes: spin-coating the prepolymer of polydimethylsiloxane onto the second elastic layer by spin coating, and heating and curing the spin-coated prepolymer of polydimethylsiloxane to obtain the bioadhesive layer.

[0020] In some embodiments, the prepolymer of the polydimethylsiloxane includes a main agent and a crosslinking agent, wherein the crosslinking agent accounts for 1%-5% by mass in the prepolymer of the polydimethylsiloxane.

[0021] In some alternative embodiments, the main agent comprises a silane, and the crosslinking agent comprises an olefin.

[0022] In some embodiments, the process conditions for preparing the bio-adhesive layer on the second elastic layer include: spin coating speed of 1000rpm-3000rpm, spin coating time of 10s-60s, heating temperature of 50℃-80℃, and heating time of 30min-180min.

[0023] In some embodiments, the step of preparing the first elastic layer includes: spin-coating a prepolymer or emulsion of the first elastomer material onto a substrate by spin coating, and then heating and curing the spin-coated prepolymer or emulsion of the first elastomer material to obtain the first elastic layer.

[0024] In some embodiments, the process conditions for preparing the first elastic layer include: spin coating speed of 500 rpm to 5000 rpm, spin coating time of 10 s to 60 s, heating temperature of 30 ℃ to 100 ℃, and heating time of 30 min to 180 min.

[0025] In some embodiments, the step of preparing the second elastic layer on the conductive layer includes: spin-coating a prepolymer or emulsion of the second elastomeric material onto the conductive layer by spin coating, and then heating and curing the spin-coated prepolymer or emulsion of the second elastomeric material to obtain the second elastic layer.

[0026] In some embodiments, the process conditions for preparing the second elastic layer on the conductive layer include: spin coating speed of 500 rpm to 5000 rpm, spin coating time of 10 s to 60 s, heating temperature of 30 ℃ to 100 ℃, and heating time of 30 min to 180 min.

[0027] In some embodiments, the step of fabricating the conductive layer on the first elastic layer includes:

[0028] S21. The nano-carbon material assembly film is transferred onto the first elastic layer using the dip-coating method, and then dried by gas purging.

[0029] S22. Repeat step S21 to obtain a conductive layer formed by the multilayer transferred nano-carbon material assembly film.

[0030] In some embodiments, the number of transfer layers in the nano-carbon material assembly film in the conductive layer is 1 to 15 layers.

[0031] In some embodiments, the gas includes one or more of nitrogen and argon.

[0032] A third aspect of this application provides the application of the electronic skin described in the first aspect of this application or the electronic skin prepared by the preparation method described in the second aspect of this application in the preparation of electronic devices.

[0033] Compared with traditional technologies, the above-mentioned electronic skin, its preparation method, and its application have at least the following advantages:

[0034] The aforementioned polydimethylsiloxane can give the bio-adhesive layer a certain degree of adhesion and flexibility, giving the bio-adhesive layer excellent conformal adhesion performance when in contact with the skin substrate, and through the combined use of the bio-adhesive layer, the first elastic layer, the conductive layer and the second elastic layer, the electronic skin's resistance to water flow impact interference is effectively improved. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the electronic skin and skin substrate according to one embodiment of this application.

[0036] Figure 2 These are morphology images of the electronic skin prepared in Example 1 of this application on different substrates; Figure 2 The base of a is the skin on the inside of the wrist. Figure 2 The base in b is the skin at the finger joints. Figure 2 The substrate in c is made of silicone rubber (Ecoflex, SmoothOn) that replicates the texture of pigskin.

[0037] Figure 3 This image shows the adhesion test results of the bio-adhesive layer in the electronic skin prepared in Example 1 of this application in air and water.

[0038] Figure 4 This is a comparison diagram of the conformal adhesion performance of the electronic skin prepared in Example 1 and Comparative Example 1 of this application.

[0039] Figure 5 This is a comparison diagram showing the water flow impact resistance of the electronic skin prepared in Example 1 and Comparative Example 1 of this application; Figure 5 a represents the electronic skin prepared in Example 1, with a water flow velocity of 4 m / s. -1 ; Figure 5 b represents the electronic skin prepared in Comparative Example 1, with a water flow velocity of 0.5 m / s. -1 .

[0040] Figure 6 Pulse measurement images of the electronic skin prepared in Example 1 of this application in static and dynamically disturbed water bodies; Figure 6 a represents a static water body. Figure 6 b represents dynamically disturbed water.

[0041] Figure 7 This is a schematic diagram of the robotic arm operation of the electronic skin prepared in Example 1 of this application under a water flow impact environment; Figure 7 'a' represents a finger-extended posture. Figure 7 b represents a partially bent finger posture.

[0042] Explanation of reference numerals in the attached figures:

[0043] 10-Electronic skin; 11-First elastic layer; 12-Conductive layer; 13-Second elastic layer; 14-Bio-adhesive layer; 20-Skin. Detailed Implementation

[0044] The technical solution of this application will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "one or more" as used herein includes any and all combinations of one or more of the associated listed items. The term "multiple" in this application means at least two, such as two, three, etc., unless otherwise expressly specified. In this application, the technical features described in an open-ended manner include both closed-ended technical solutions consisting of the listed features and open-ended technical solutions including the listed features.

[0046] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0047] Unless otherwise shown or indicated in the operational embodiments, all figures used to represent the amounts, physicochemical properties, etc., of ingredients in the specification and claims are to be understood to be adjusted by the term "about" in all cases. For example, therefore, unless stated to the contrary, the numerical parameters listed in the foregoing specification and appended claims are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired characteristics by utilizing the teachings disclosed herein. The use of numerical ranges indicated by endpoints includes all numbers within that range and any range within that range; for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4, and 5, etc.

[0048] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0049] In this application, terms such as "first aspect," "second aspect," and "third aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," and "third" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0050] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0051] To achieve a stable electronic skin device-skin interface, two strategies are typically employed. One involves securing the device to the skin using external mechanical fixation materials such as tape and bandages, which often leads to discomfort and inconvenience. The other strategy utilizes intrinsically adhesive materials or bio-inspired adhesive biomimetic structures, such as mussel-inspired adhesives with catechol groups or octopus-inspired suction cup-like adhesive structures with multi-level hierarchical structures. These designs may cause irritation or require delicate manufacturing processes. Furthermore, the adhesion of wearable devices to severe water impacts still needs improvement. The design of the electronic skin device-skin interface is fundamental to achieving excellent sensing performance and resistance to water impact interference, and is crucial for ensuring the application of electronic skin in various complex aquatic environments.

[0052] The electronic skin of this application includes a bioadhesive layer and a strain-sensing layer. The strain-sensing layer is located on at least one surface of the bioadhesive layer. The strain-sensing layer includes a first elastic layer, a conductive layer, and a second elastic layer sequentially stacked along its thickness direction. The second elastic layer is in contact with the bioadhesive layer. The bioadhesive layer includes polydimethylsiloxane (PDMS). PDMS enables the bioadhesive layer to have a certain degree of adhesion and flexibility, giving it excellent conformal adhesion performance when in contact with the skin substrate. Furthermore, the combined use of the bioadhesive layer, the first elastic layer, the conductive layer, and the second elastic layer effectively improves the electronic skin's resistance to water flow impact interference. Traditional electronic skin can only be used in dry environments, while the electronic skin of this application maintains a stable device-skin interface even under complex aquatic environmental interference conditions, especially exhibiting excellent resistance to water flow impact interference.

[0053] One embodiment of this application provides an electronic skin, including a bioadhesive layer and a strain sensing layer. The strain sensing layer is located on at least one surface of the bioadhesive layer. The strain sensing layer includes a first elastic layer, a conductive layer, and a second elastic layer sequentially stacked along its thickness direction. The second elastic layer is in contact with the bioadhesive layer, and the bioadhesive layer includes polydimethylsiloxane.

[0054] The aforementioned polydimethylsiloxane imparts a certain degree of adhesion and flexibility to the bio-adhesive layer, giving it excellent conformal adhesion properties when in contact with the skin substrate. Furthermore, the combined use of the bio-adhesive layer, the first elastic layer, the conductive layer, and the second elastic layer effectively improves the electronic skin's resistance to water flow impact and the interfacial stability between the electronic skin device and the skin. Even in extreme water-related environments, such as under conditions of severe water flow impact, the electronic skin device maintains excellent stability at the skin interface.

[0055] In some implementation methods, reference may be made to Figure 1 The electronic skin 10 includes a bioadhesive layer 14 and a strain-sensing layer. The strain-sensing layer is located on at least one surface of the bioadhesive layer 14. The strain-sensing layer includes a first elastic layer 11, a conductive layer 12, and a second elastic layer 13, which are sequentially stacked along its thickness direction. The second elastic layer 13 is in contact with the bioadhesive layer 14. The electronic skin 10 can be attached to the skin 20.

[0056] In some embodiments, the soluble solids content of the bio-adhesive layer is 20%-70%. Controlling the soluble solids content of the bio-adhesive layer within this range allows the material in the adhesive layer to have a suitable degree of cross-linking, further improving the adhesiveness of the bio-adhesive layer and imparting excellent conformal adhesion properties when in contact with skin. This further effectively improves the resistance of electronic skin to water flow impact interference and the interfacial stability between the electronic skin device and the skin. It is understood that the soluble solids content of the bio-adhesive layer includes, but is not limited to: 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 66%, and 70%.

[0057] In some embodiments, the soluble solids content of the bio-adhesive layer is 40%-70%. Controlling the soluble solids content of the bio-adhesive layer to 40%-70% can further improve the adhesiveness of the bio-adhesive layer, giving it excellent conformal adhesion properties when in contact with the skin, thereby further effectively improving the electronic skin's resistance to water flow impact interference and the interfacial stability between the electronic skin device and the skin.

[0058] In some embodiments, the thickness of the bio-adhesive layer is 10 μm-100 μm. Controlling the thickness of the bio-adhesive layer within this range can reduce the overall thickness of the electronic skin and further effectively improve the electronic skin's resistance to water flow impact interference, as well as the interfacial stability between the electronic skin device and the skin. It is understood that the thickness of the bio-adhesive layer includes, but is not limited to: 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, and 100 μm.

[0059] In some embodiments, the first elastic layer includes a first elastomeric material, and the second elastic layer includes a second elastomeric material. The elastomeric materials contained in the first and second elastic layers can improve their flexibility, thereby further improving the electronic skin's resistance to water flow impact interference, as well as the electronic skin's flexibility and interface stability.

[0060] In some embodiments, the thicknesses of the first elastic layer and the second elastic layer are each independently between 1 μm and 1000 μm. Controlling the thicknesses of the first and second elastic layers within the aforementioned range can further effectively improve the electronic skin's resistance to water flow impact interference and the interfacial stability between the electronic skin device and the skin. It is understood that the thicknesses of the first and second elastic layers include, but are not limited to: 1 μm, 10 μm, 30 μm, 50 μm, 80 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, and 1000 μm. Further, the thicknesses of the first and second elastic layers are between 1 μm and 100 μm. Controlling the thicknesses of the first and second elastic layers to between 1 μm and 100 μm can further reduce the overall thickness of the electronic skin.

[0061] In some embodiments, the first and second elastomer materials each independently comprise one or more of polydimethylsiloxane (PDMS), platinum-catalyzed silica gel (Ecoflex), polyurethane (PU), styrene-butadiene-styrene block copolymer (SBS), and styrene-ethylene-butene-styrene block copolymer (SEBS). These types of elastomer materials can further enhance the flexibility of the first and second elastic layers, thereby further improving the electronic skin's resistance to water flow impact, as well as its flexibility and interfacial stability.

[0062] In some embodiments, the conductive layer comprises a carbon nanomaterial.

[0063] In some embodiments, the thickness of the conductive layer is 10nm-500nm. It is understood that the thickness of the conductive layer includes, but is not limited to: 10nm, 50nm, 100nm, 200nm, 300nm, 400nm, and 500nm.

[0064] In some embodiments, the carbon nanomaterial includes one or more of carbon spheres, carbon nanotubes, and graphene.

[0065] Another embodiment of this application provides a method for preparing the above-mentioned electronic skin, comprising the following steps:

[0066] Prepare the first elastic layer;

[0067] A conductive layer is prepared on the first elastic layer;

[0068] A second elastic layer is prepared on the conductive layer;

[0069] A bio-adhesive layer is prepared on the second elastic layer.

[0070] The above preparation method can more easily prepare electronic skin and enables large-scale production of electronic skin.

[0071] In some embodiments, the step of preparing the bioadhesive layer on the second elastic layer includes: spin-coating a prepolymer of polydimethylsiloxane onto the second elastic layer using a spin-coating method, and then heating and curing the prepolymer of polydimethylsiloxane to obtain the bioadhesive layer. This allows for a simpler preparation of the bioadhesive layer. Notably, during the peeling process of the bioadhesive layer, multiple flexible plastic film strips are sequentially adhered to the non-adhesive side of the electronic skin as a substrate support to prevent self-curling and facilitate subsequent operations.

[0072] In some embodiments, the prepolymer solution of polydimethylsiloxane includes a main agent and a crosslinking agent, wherein the crosslinking agent accounts for 1%-5% by mass in the prepolymer solution of polydimethylsiloxane. The main agent includes silane, and the crosslinking agent includes olefin. Controlling the content of the crosslinking agent within the above range can further improve the adhesiveness of the bioadhesive layer, giving it excellent conformal adhesion properties when in contact with skin, thereby further effectively improving the resistance of electronic skin to water flow impact interference and the interfacial stability between the electronic skin device and the skin. It is understood that the mass percentage of the crosslinking agent in the prepolymer solution of polydimethylsiloxane can be, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc.

[0073] In some embodiments, the process conditions for preparing the bio-adhesive layer on the second elastic layer include: spin coating speed of 1000 rpm-3000 rpm, spin coating time of 10 s-60 s, heating temperature of 50℃-80℃, and heating time of 30 min-180 min. Controlling these process conditions can yield a thin and uniformly thick bio-adhesive layer. It is understood that the spin coating speed includes, but is not limited to: 1000 rpm, 1300 rpm, 1500 rpm, 1800 rpm, 2000 rpm, 2300 rpm, 2500 rpm, 2800 rpm, and 3000 rpm; the spin coating time includes, but is not limited to: 10 s, 20 s, 30 s, 40 s, 50 s, and 60 s; the heating temperature includes, but is not limited to: 50℃, 60℃, 70℃, and 80℃; and the heating time includes, but is not limited to: 30 min, 50 min, 70 min, 90 min, 110 min, 130 min, 150 min, and 180 min.

[0074] In some embodiments, the step of preparing the first elastic layer includes: spin-coating a prepolymer or emulsion of the first elastomer material onto a substrate using a spin-coating method, and then heating and curing the spin-coated prepolymer or emulsion of the first elastomer material to obtain the first elastic layer. This allows for a simpler preparation of the first elastic layer.

[0075] In some embodiments, the process conditions for preparing the first elastic layer include: spin coating speed of 500 rpm to 5000 rpm, spin coating time of 10 s to 60 s, heating temperature of 30°C to 100°C, and heating time of 30 min to 180 min. This results in a first elastic layer that is relatively thin and has a uniform thickness. It is understood that the spin coating speed includes, but is not limited to: 500rpm, 1000rpm, 1500rpm, 2000rpm, 2500rpm, 3000rpm, 3500rpm, 4000rpm, 4500rpm, and 5000rpm; the spin coating time includes, but is not limited to: 10s, 20s, 30s, 40s, 50s, and 60s; the heating temperature includes, but is not limited to: 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, and 100℃; and the heating time includes, but is not limited to: 30min, 50min, 70min, 90min, 110min, 130min, 150min, and 180min.

[0076] In some embodiments, the step of preparing the second elastic layer on the conductive layer includes: spin-coating a prepolymer or emulsion of the second elastomer material onto the conductive layer using a spin-coating method, and then heating and curing the spin-coated prepolymer or emulsion of the second elastomer material to obtain the second elastic layer. This allows for a simpler preparation of the second elastic layer.

[0077] In some embodiments, the process conditions for preparing the second elastic layer on the conductive layer include: spin coating speed of 500 rpm to 5000 rpm, spin coating time of 10 s to 60 s, heating temperature of 30°C to 100°C, and heating time of 30 min to 180 min. This results in a thinner and more uniform second elastic layer. It is understood that the spin coating speed includes, but is not limited to: 500rpm, 1000rpm, 1500rpm, 2000rpm, 2500rpm, 3000rpm, 3500rpm, 4000rpm, 4500rpm, and 5000rpm; the spin coating time includes, but is not limited to: 10s, 20s, 30s, 40s, 50s, and 60s; the heating temperature includes, but is not limited to: 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, and 100℃; and the heating time includes, but is not limited to: 30min, 50min, 70min, 90min, 110min, 130min, 150min, and 180min.

[0078] In some embodiments, the step of fabricating a conductive layer on the first elastic layer includes:

[0079] S21. The nano-carbon material assembly film is transferred onto the first elastic layer using the dip-coating method and then dried by gas purging.

[0080] S22. Repeat step S21 to obtain a conductive layer formed by the multilayer transferred nano-carbon material assembly film.

[0081] Therefore, the conductive layer can be prepared more easily.

[0082] In some embodiments, the number of transfer layers in the conductive layer of the nano-carbon material assembly film is 1 to 15.

[0083] In some embodiments, the gas includes one or more of nitrogen and argon.

[0084] Another embodiment of this application provides the application of the above-described electronic skin or the electronic skin prepared by the above-described preparation method in the preparation of electronic devices.

[0085] The aforementioned electronic skin has numerous applications, such as powering electronic devices and signal sensing. These electronic devices include, but are not limited to, wearable devices, intelligent robots, bionic devices, intelligent prosthetics, sensors, electrodes, pedometers, and speedometers. Due to its excellent device-skin interface stability and resistance to water flow impact, the electronic skin is suitable for both dry and wet applications, particularly wearable sensing applications in complex and dynamic aquatic environments such as surfing, swimming, and showering.

[0086] The present application will be further described in detail below with reference to specific embodiments and comparative examples. Experimental parameters not specified in the following specific embodiments should first be referred to the guidelines given in this application, and may also be referred to experimental manuals or other experimental methods known in the art, or the experimental conditions recommended by the manufacturer. It is understood that the instruments and materials used in the following embodiments are relatively specific, and may not be limited to these in other specific embodiments.

[0087] Example 1

[0088] A method for preparing a conformal self-adhesive electronic skin includes the following steps:

[0089] (1) Preparation of Ecoflex prepolymer: Component A (Ecoflex 00-30, Smooth on) and component B (Ecoflex 00-30, Smooth on) are prepared in a weight ratio of 1:1 and mixed uniformly using a high-speed mixer to obtain Ecoflex prepolymer.

[0090] (2) Preparation of substrate: Cut a 5cm*5cm PET plastic sheet and fix a 5cm×1cm PI film on both sides of the PET plastic sheet to form a substrate;

[0091] (3) Preparation of the first elastic layer: Ecoflex prepolymer liquid was spin-coated on the substrate by spin coating. The spin coating speed was set to 3000 rpm and the spin coating time was 30 s. Then the spin-coated sample was placed in an oven for heating and curing. The heating temperature was 60℃ and the heating time was 30 min to obtain the first elastic layer with a thickness of about 40 μm.

[0092] (4) Preparation of conductive layer: The graphene assembly film at the air-water interface is transferred to the first elastic layer by the dip-coating method and dried by nitrogen gas purging at room temperature; through 10 cycles of transfer and drying, a conductive layer formed by multilayer transferred graphene assembly film is obtained with a thickness of 500 nm; copper wires are led out from the graphene assembly film above the flexible non-stretchable PI plastic film fixed on both sides and fixed with silver paste.

[0093] (5) Preparation of the second elastic layer: Ecoflex film is encapsulated on the conductive layer by spin coating (that is, Ecoflex prepolymer liquid is spin coated on the conductive layer). The spin coating speed is set to 3000 rpm and the spin coating time is 30 s. Then the spin-coated sample is placed in an oven for heating and curing at 60 ℃ for 30 min to obtain a second elastic layer with a thickness of about 40 μm. Thus, the strain sensing layer based on Ecoflex film wrapped with graphene film is constructed with a thickness of about 80 μm.

[0094] (6) Preparation of bioadhesive layer: A small amount of silane crosslinking agent (Sylgard 184, DOW) (mass fraction 1%) was added to the olefin main agent (Sylgard 184, DOW) and mixed uniformly using a high-speed mixer to prepare PDMS prepolymer liquid; the prepared PDMS prepolymer liquid was spin-coated onto the second elastic layer by spin coating, with the spin coating speed set at 2000 rpm and the spin coating time at 60 s. The spin-coated sample was then placed in an oven for heating and curing at 60 ℃ for 180 min to prepare a bioadhesive layer with a thickness of about 50 μm and a soluble solids content of 66%; the sensor on the substrate was cut to a specific size and peeled off from the PET plastic substrate. The thickness of the prepared conformal self-adhesive electronic skin was about 130 μm.

[0095] Example 2

[0096] The method for preparing the conformal self-adhesive electronic skin in this embodiment is basically the same as that in Example 1, except that step (6) is different.

[0097] (6) Preparation of bioadhesive layer: A small amount of crosslinking agent (Sylgard 184, DOW) (5% by mass) was added to the main agent (Sylgard 184, DOW) and mixed evenly using a high-speed mixer to prepare PDMS prepolymer solution; the prepared PDMS prepolymer solution was spin-coated onto the second elastic layer by spin coating method, with the spin coating speed set at 2000 rpm and the spin coating time at 60 s. The spin-coated sample was then placed in an oven for heating and curing at 60 ℃ for 180 min to prepare a bioadhesive layer with a thickness of about 50 μm and a soluble solids content of 20%; the sensor on the substrate was cut into specific sizes and peeled off from the PET plastic substrate. The thickness of the prepared conformal self-adhesive electronic skin was about 130 μm.

[0098] Example 3

[0099] The method for preparing the conformal self-adhesive electronic skin in this embodiment is basically the same as that in Example 1, except that step (6) is different.

[0100] (6) Preparation of bioadhesive layer: A small amount of crosslinking agent (Sylgard 184, DOW) (mass fraction 3%) was added to the main agent (Sylgard 184, DOW) and mixed uniformly using a high-speed mixer to prepare PDMS prepolymer solution; the prepared PDMS prepolymer solution was spin-coated onto the second elastic layer by spin coating method, with the spin coating speed set at 2000 rpm and the spin coating time at 60 s. The spin-coated sample was then placed in an oven for heating and curing at a temperature of 60 ℃ for 180 min to prepare a bioadhesive layer with a thickness of about 50 μm and a soluble solids content of 45%; the sensor on the substrate was cut to a specific size and peeled off from the PET plastic substrate. The thickness of the prepared conformal self-adhesive electronic skin was about 130 μm.

[0101] Example 4

[0102] The method for preparing the conformal self-adhesive electronic skin in this embodiment is basically the same as that in Example 1, except that steps (3) and (5) are different.

[0103] (3) Preparation of the first elastic layer: The prepared Ecoflex prepolymer was diluted with n-hexane solvent, and the diluted Ecoflex prepolymer was applied to the substrate by drop coating. A certain amount of drop coating was added, and then the sample after drop coating was placed in an oven for heating and curing. The heating temperature was 60℃ and the heating time was 30min, resulting in a first elastic layer with a thickness of about 250μm.

[0104] (5) Preparation of the second elastic layer: The prepared Ecoflex prepolymer solution was diluted with n-hexane solvent. The diluted Ecoflex prepolymer solution was then drop-coated onto the conductive layer by a drop-coating method. A certain amount of drop-coating solution was added. The drop-coated sample was then placed in an oven for heating and curing at a temperature of 60°C for 30 minutes to obtain a second elastic layer with a thickness of about 250 μm. This enabled the construction of a conventional electronic skin based on a graphene film wrapped with an Ecoflex film, with a thickness of about 500 μm.

[0105] Comparative Example 1

[0106] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that step (6) is omitted and steps (3) and (5) are different.

[0107] (3) Preparation of the first elastic layer: The prepared Ecoflex prepolymer was diluted with n-hexane solvent, and the diluted Ecoflex prepolymer was applied to the substrate by drop coating. A certain amount of drop coating was added, and then the sample after drop coating was placed in an oven for heating and curing. The heating temperature was 60℃ and the heating time was 30min, resulting in a first elastic layer with a thickness of about 250μm.

[0108] (5) Preparation of the second elastic layer: The prepared Ecoflex prepolymer solution was diluted with n-hexane solvent. The diluted Ecoflex prepolymer solution was then drop-coated onto the conductive layer by a drop-coating method. A certain amount of drop-coating solution was added. The drop-coated sample was then placed in an oven for heating and curing at a temperature of 60°C for 30 minutes to obtain a second elastic layer with a thickness of about 250 μm. This enabled the construction of a conventional electronic skin based on a graphene film wrapped with an Ecoflex film, with a thickness of about 500 μm.

[0109] The soluble solids content of the bio-adhesive layer in each embodiment was tested. Furthermore, the electronic skins prepared in each embodiment and Comparative Example 1 were subjected to air and underwater adhesion tests, conformal adhesion tests, water flow impact resistance tests, tensile-resistance strain sensing performance tests, human health monitoring under complex aquatic conditions, and robotic arm manipulation tests. The test methods are as follows:

[0110] (a) Air and underwater adhesion testing: A 90-degree peel test was conducted using a universal testing machine (Shimadzu, AGS-X, 5N pressure sensor) to measure the adhesion strength between the bio-adhesive layer and the skin. Adhesion force tests were performed in both air and underwater environments. The tensile rate was set to 50 mm / min. -1 The viscous force is calculated using the stable maximum tensile force and the sample width.

[0111] (b) Characterization method of soluble solids content: The bioadhesive membrane was immersed in hexane solvent for 3 days. The specific operation was to soak the bioadhesive membrane sample on the PET substrate in hexane solvent for 3 days, and replace the solvent every day. Then the sample was taken out and dried at 70°C for 1 hour. The mass fraction of soluble solids content was calculated based on the mass of the original bioadhesive membrane and the mass of the dried bioadhesive membrane.

[0112] (c) Conformal Adhesion Performance Testing: To evaluate the conformal adhesion performance of the electronic skin on rough substrates, the prepared electronic skin was adhered to different substrates. The substrates selected were skin from the inner wrist, skin at the finger joints, and a substrate made of silicone rubber (Ecoflex, Smooth On) replicating the texture of pigskin. Three-dimensional optical microscopic images and quantitative surface profile curves were recorded using a confocal laser scanning microscope (Leica, DCM-8, Germany).

[0113] (d) Water Flow Impact Resistance Test: To evaluate the water flow impact resistance of the electronic skin, the sample was attached to the skin of the wrist, with the hand held horizontally and the palm vertical. The stability of the electronic skin device-skin interface was then investigated by applying water flows at different velocities from above. The water flow velocity was calculated using volumetric flow rate and pipe diameter. v = 4Q / πd 2 Where v is the water flow velocity, Q is the volumetric flow velocity, and d is the pipe diameter.

[0114] (e) Strain sensing performance test: A controllable tensile strain was applied to the electronic skin sensor using a universal testing machine, and the electrical signal of the sensor under strain deformation was recorded synchronously using an electrochemical workstation (CHI760E, CH Instruments Inc.).

[0115] (f) Sensing applications in complex aquatic environments: The prepared electronic skin was adhered to the fingertips, and then the pulse signals of the fingertips were monitored using an electrochemical station (CHI760E, CH Instruments Inc.) in both static and disturbed water. The prepared electronic skin was adhered to the joints of the five fingers, and under continuous water flow impact, different hand gestures were made to control a robotic hand (Gihand, Zhongling Technology).

[0116] Figure 2 The electronic skin prepared in Example 1 shows that it has good conformal adhesion properties with the skin on the inside of the wrist, the skin at the finger joints, and the replicated skin. Figure 3 This demonstrates that the bioadhesive layer in the electronic skin prepared in Example 1 exhibits good bioadhesive properties to the skin substrate both in air and underwater.

[0117] Figure 4The conformal adhesion performance of the electronic skin is shown to increase significantly with decreasing thickness. When attached to a skin template, the surface profile curve of the electronic skin prepared in Example 1 shows very obvious fluctuations, with the narrowest width being 700 μm and the deepest depth being 80 μm. In contrast, the electronic skin prepared in Comparative Example 1 does not have obvious peaks and troughs, indicating that the ultrathin electronic skin prepared in Example 1 can make high-fidelity contact with the textured surface of the skin.

[0118] from Figure 5 It can be seen that the electronic skin prepared in Example 1, under the impact of intense water flow (4 m·s), exhibits good performance. -1 The electronic skin remained stably attached to the skin surface, while the electronic skin prepared in Comparative Example 1 remained stable even under very low water flow impact (0.5 m·s⁻¹). -1 This resulted in the device detaching from the skin. Furthermore, the electronic skin prepared in Examples 2 and 4 could withstand relatively intense water flow impact (1 m·s⁻¹). -1 The electronic skin prepared in Example 3 remains stably attached to the skin surface and can withstand intense water flow (2 m·s) even under strong water impact. -1 It remains stably attached to the skin surface.

[0119] The electronic skin prepared in Example 1 is suitable for stable sensing applications under complex aquatic environmental conditions. For example... Figure 6 As shown, pulse signals can be monitored unaffected when the fingertip remains still in water. Even when the water is agitated, causing significant interference, the pulse signals are still clearly recorded. Figure 7 The results show that even under continuous water flow impact, the electronic skin can stably control various hand gestures of the robotic hand. Furthermore, the electronic skin prepared in Example 3 is also suitable for stable sensing applications in complex aquatic environments, and its test results are consistent with... Figures 6-7 resemblance.

[0120] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0121] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. An electronic skin, characterized in that, The device includes a bioadhesive layer and a strain-sensing layer. The strain-sensing layer is located on at least one surface of the bioadhesive layer. The strain-sensing layer comprises a first elastic layer, a conductive layer, and a second elastic layer sequentially stacked along its thickness direction. The second elastic layer is in contact with the bioadhesive layer. The bioadhesive layer comprises polydimethylsiloxane. The soluble solids content of the bioadhesive layer is 40%-70%, and the thickness of the bioadhesive layer is 10 μm-100 μm. The electronic skin operates at 2 m·s -1 It can still conformally adhere to the skin surface even under the impact of the above water flow; The method for preparing the electronic skin includes the following steps: Prepare the first elastic layer; The conductive layer is prepared on the first elastic layer; The second elastic layer is prepared on the conductive layer; The bio-adhesive layer is prepared on the second elastic layer; The step of preparing the bio-adhesive layer on the second elastic layer includes: spin-coating the prepolymer of polydimethylsiloxane onto the second elastic layer by spin coating, and heating and curing the prepolymer of polydimethylsiloxane after spin coating to obtain the bio-adhesive layer; the prepolymer of polydimethylsiloxane includes a main agent and a crosslinking agent, and the crosslinking agent accounts for 1%-5% of the mass percentage of the prepolymer of polydimethylsiloxane.

2. The electronic skin according to claim 1, characterized in that, The first elastic layer comprises a first elastomeric material, and the second elastic layer comprises a second elastomeric material.

3. The electronic skin according to claim 2, characterized in that, The thickness of the first elastic layer and the second elastic layer are each independently between 1 μm and 1000 μm.

4. The electronic skin according to claim 2, characterized in that, The thickness of the first elastic layer and the second elastic layer are each independently 1μm-100μm.

5. The electronic skin according to claim 2, characterized in that, The first elastomer material and the second elastomer material each independently include one or more of polydimethylsiloxane, platinum-catalyzed silica gel, polyurethane, styrene-butadiene-styrene block copolymer and styrene-ethylene-butene-styrene block copolymer.

6. The electronic skin according to claim 1 or 2, characterized in that, The conductive layer comprises nano-carbon materials.

7. The electronic skin according to claim 6, characterized in that, The thickness of the conductive layer is 10nm-500nm.

8. The electronic skin according to claim 6, characterized in that, The nanomaterials include one or more of carbon spheres, carbon nanotubes, and graphene.

9. The electronic skin according to claim 1, characterized in that, Its features are, The soluble solids content of the bio-adhesive layer is 66%-70%.

10. The electronic skin according to claim 1, characterized in that, The thickness of the bio-adhesive layer is 50μm-100μm.

11. The electronic skin according to claim 1, characterized in that, The crosslinking agent accounts for 1%-3% by mass in the prepolymer solution of the polydimethylsiloxane.

12. The electronic skin according to claim 1, characterized in that, The main agent includes silane, and the crosslinking agent includes olefin.

13. The electronic skin according to claim 1, characterized in that, The process conditions for preparing the bio-adhesive layer on the second elastic layer include: spin coating speed of 1000rpm-3000rpm, spin coating time of 10s-60s, heating temperature of 50℃-80℃, and heating time of 30min-180min.

14. The electronic skin according to claim 1, characterized in that, The method for preparing the electronic skin satisfies at least one of the following conditions (1)-(4): (1) The step of preparing the first elastic layer includes: spin coating a prepolymer liquid or emulsion of the first elastomer material onto the substrate by spin coating, and heating and curing the spin-coated prepolymer liquid or emulsion of the first elastomer material to obtain the first elastic layer. (2) The step of preparing the first elastic layer includes: spin coating a prepolymer liquid or emulsion of the first elastomer material onto the substrate by spin coating, and heating and curing the spin-coated prepolymer liquid or emulsion of the first elastomer material to obtain the first elastic layer; the process conditions for preparing the first elastic layer include: spin coating speed of 500rpm-5000rpm, spin coating time of 10s-60s, heating temperature of 30℃-100℃, and heating time of 30min-180min; (3) The step of preparing the second elastic layer on the conductive layer includes: spin coating the prepolymer liquid or emulsion of the second elastomer material onto the conductive layer by spin coating method, and heating and curing the spin-coated prepolymer liquid or emulsion of the second elastomer material to obtain the second elastic layer; (4) The step of preparing the second elastic layer on the conductive layer includes: spin coating the prepolymer liquid or emulsion of the second elastomer material onto the conductive layer by spin coating, and heating and curing the spin-coated prepolymer liquid or emulsion of the second elastomer material to obtain the second elastic layer; the process conditions for preparing the second elastic layer on the conductive layer include: spin coating speed of 500rpm-5000rpm, spin coating time of 10s-60s, heating temperature of 30℃-100℃, and heating time of 30min-180min.

15. The electronic skin according to any one of claims 1-5 and 9-14, characterized in that, The step of preparing the conductive layer on the first elastic layer includes: S21. The nano-carbon material assembly film is transferred onto the first elastic layer using the dip-coating method, and then dried by gas purging. S22. Repeat step S21 to obtain a conductive layer formed by the multilayer transferred nano-carbon material assembly film.

16. The electronic skin according to claim 15, characterized in that, The number of transfer layers in the nano-carbon material assembly film in the conductive layer is 1 to 15.

17. The electronic skin according to claim 15, characterized in that, The gas includes one or more of nitrogen and argon.

18. The use of the electronic skin according to any one of claims 1-17 in the manufacture of electronic devices.

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