An ultra-flexible friction sensor and a preparation method and application thereof

Abstract

The application discloses a super-flexible friction sensor and a preparation method and application thereof, and belongs to the technical field of flexible electronics. The super-flexible friction sensor comprises a sensing layer; the sensing layer comprises a substrate, a first conductive layer, a photoresist layer, an insulating polymer layer and a second conductive layer which are sequentially stacked; the material of the substrate comprises poly-p-xylylene, and the thickness of the substrate is 0.1-3 microns; and the thickness of the super-flexible friction sensor is 20-40 microns. Compared with a conventional friction sensor, the super-flexible friction sensor has smaller thickness, and is more flexible and sensitive. The application further provides a preparation method and application of the super-flexible friction sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flexible electronic technology, in particular to a super-flexible friction sensor and a preparation method and application thereof. BACKGROUND

[0002] At present, flexible wearable electronic devices are widely concerned in many fields, including health monitoring, sports fitness, wearable electronic technology, etc. Different from the hard form shown by traditional electronic devices, flexible wearable electronic devices show completely different mechanical properties such as bendability and foldability by using flexible substrates and electronic design. Thanks to the flexible electronic devices that can well adapt to various curved surfaces of the human body, realize close fitting with the skin, thereby greatly improving the accuracy and comfort of its use in the field of health monitoring, etc. In addition, flexible wearable electronic devices also have advantages including portability, low power consumption, reliability, etc., making their application in the fields of medical treatment, sports fitness, etc. increasingly widespread.

[0003] As a new type of renewable energy technology, friction nanogenerator realizes the collection and conversion of electric signals through the contact electrification and electrostatic induction between materials, and shows great commercial value in the fields of wearable devices and signal sensing. At the same time, friction nanosensor also has advantages such as flexibility, lightness, stable operation, high sensitivity and low cost, and can be applied to the detection of body motion signals. The flexible friction nanosensor prepared by using friction nanogenerator technology can realize rapid and high-sensitivity detection of the motion state of the target area.

[0004] Although friction nanotechnology has been widely used in the sensing field to record changes in human motion signals, the existing friction nanosensor still has problems such as poor sensitivity, poor flexibility due to the overall thickness of the device, poor air permeability for long-term wear, limited application scenarios, etc. Some friction nanosensors also need to be tightly pressed on the skin by applying external force to work, which greatly affects the wearing comfort, is not suitable for long-term wear, and limits the biosensing application of the sensor. Therefore, how to construct a flexible friction nanosensor with high sensitivity, suitable for wearing, and mass production is crucial. SUMMARY

[0005] The present application aims to at least solve one of the problems in the prior art. To this end, the present application provides a super-flexible friction sensor, which is thinner than the conventional friction sensor, and therefore has higher flexibility; and the sensitivity is significantly improved through the design of the structure.

[0006] The present application also provides a preparation method of the super-flexible friction sensor.

[0007] The present application also provides an application of the super-flexible friction sensor.

[0008] According to the embodiment of the first aspect of the present application, an ultra-flexible friction sensor is provided, the ultra-flexible friction sensor comprising a sensing layer;

[0009] The sensing layer comprises a substrate, a first conductive layer, a photoresist layer, an insulating polymer layer and a second conductive layer which are sequentially stacked;

[0010] The substrate is made of parylene and has a thickness of 0.1-3 microns;

[0011] The ultra-flexible friction sensor has a thickness of 20-40 microns.

[0012] The ultra-flexible friction sensor according to the embodiment of the present application has at least the following beneficial effects:

[0013] (1) The thickness of the flexible friction sensor greatly affects the close contact with the part to be detected, and further affects the precision of capturing the movement. In the sensing layer of the conventional flexible friction sensor, polyethylene terephthalate (PET), polyethylene (PE) and other high molecular polymer materials are generally used. The thickness of such polymer materials is usually more than 20 microns. Further, the substrate with such thickness is provided to match the thickness of other layers. Therefore, the friction sensor in the conventional technology has a relatively large thickness, and there is a gap between the target area and the sensor, which makes it difficult to capture the small movement signal and reduces the sensitivity.

[0014] In the present application, a parylene layer is used, which can be deposited by vacuum deposition and the like, so that a thin film with a thickness of 0.1-3 microns can be formed. Further, the sensing layer provided in the present application also includes a photoresist layer. Due to the special properties of the photoresist, a very thin thickness can also be obtained. The substrate of the present application is thin, and other flexible structures matched therewith are also thin. The overall thickness of the ultra-flexible friction sensor is 20-40 microns. When the ultra-flexible friction sensor is attached to the target area, it can perfectly attach to the curved surface of the target area. When the target area moves, the movement change can be well transmitted to the sensor, and the small signal change can be captured, so that the sensitivity is high.

[0015] (2) The conventional flexible friction sensor generally does not include the photoresist layer. Therefore, part of the first conductive layer may come into contact with the insulating polymer layer during the operation of the flexible friction sensor, resulting in charge neutralization and no output signal, and further causing a decrease in sensitivity. The photoresist layer provided in the present application can prevent the contact neutralization of the charge during the operation, and ensure the stability of the ultra-flexible friction sensor.

[0016] (3) Due to the design of the structure and the material, the ultra-flexible friction sensor provided in the present application has the following advantages:

[0017] The application scenarios are wide, and the sensor can be used for monitoring movement signals of different parts of human body, such as blinking, lip language, finger joint bending and the like, and can also be used as a touch sensor of a robot and the like.

[0018] The sensor has high sensitivity and stability, can detect pressure changes less than 0.01 N and torsion signal changes of 1°, and can be used for capturing and monitoring micro movement signals.

[0019] The sensor has a thinner thickness and better wearing comfort, and provides a prototype demonstration and an idea for commercial application of wearable health monitoring devices.

[0020] According to some embodiments of the present application, the ultra-flexible friction sensor further comprises an adhesive layer arranged on a surface of the substrate away from the second conductive layer.

[0021] According to some embodiments of the present application, the material of the adhesive layer comprises a breathable hydrogel. Compared with conventional commercial adhesive products, the ultra-flexible friction sensor provided by the present application has better breathability, wearing comfort and biocompatibility.

[0022] According to some embodiments of the present application, the thickness of the adhesive layer is 10 μm to 30 μm. For example, it can be specifically 15 μm to 25 μm.

[0023] According to some embodiments of the present application, the material of the adhesive layer comprises a polyacrylamide / sodium alginate hydrogel or a gelatin / glycerol hydrogel.

[0024] According to some embodiments of the present application, the material of the first conductive layer is selected from at least one of gold, silver, aluminum and ITO.

[0025] According to some embodiments of the present application, the thickness of the first conductive layer is 20 nm to 50 nm. For example, it can be specifically 20 nm to 30 nm. Further specifically, it can be about 20 nm.

[0026] According to some embodiments of the present application, the type of the photoresist in the photoresist layer comprises at least one of SU-8, AZ-N4000 and NP9G.

[0027] According to some embodiments of the present application, the thickness of the photoresist layer is 500 nm to 1000 nm.

[0028] According to some embodiments of the present application, the thickness of the photoresist layer is 600 nm to 800 nm. For example, it can be specifically 650 nm to 700 nm.

[0029] According to some embodiments of the present application, the photoresist layer has a hollow pattern. Thus, a sensor with better output signal can be obtained, and the sensitivity is improved. Specifically, the hollow pattern design forms a certain gap between the insulating polymer layer and the first conductive layer of the friction sensor; and because the charges carried by the insulating polymer layer and the first conductive layer are opposite, a stable built-in electric field can be formed between the gap; when the friction sensor is subjected to external force and deforms, the steady state of the built-in electric field is destroyed and will cause the transfer of charges between the two electrode layers, thereby outputting a current signal.

[0030] According to some embodiments of the present application, the area ratio of the hollow pattern to the photoresist layer is 0-50%.

[0031] According to some embodiments of the present application, the area ratio of the hollow pattern to the photoresist layer is 15-40%. For example, it can be specifically 20-30%. For example, it can be about 25% or 35%.

[0032] According to some embodiments of the present application, the area ratio of the hollow pattern to the photoresist layer is 5-10%.

[0033] According to some embodiments of the present application, the super-flexible friction sensor further comprises an adhesive. The adhesive is used to bond the photoresist layer and the insulating polymer layer. The adhesive is arranged at the edge position of the photoresist layer and the insulating polymer layer. That is, the super-flexible friction sensor does not have an adhesive arranged in the inside, but only a small amount of adhesive is arranged at the edge contact position.

[0034] According to some embodiments of the present application, the material of the insulating polymer layer comprises FEP.

[0035] According to some embodiments of the present application, the thickness of the insulating polymer layer is 10-15 μm. For example, it can be specifically 12-13 μm.

[0036] The insulating polymer film with this thickness can be obtained from the market. At the same time, the commercially available film also has a thickness of 50-100 μm; in the traditional technology, in order to match the thickness of other layers, a film with a thickness of 50-100 μm is usually used, and if a thinner film is used, the flexible friction sensor cannot work. In the present application, by adjusting the thickness of each layer, the super-flexible friction sensor can use a thinner insulating polymer film, thereby reducing the overall thickness and improving the sensitivity.

[0037] According to some embodiments of the present application, the material of the second conductive layer is selected from at least one of gold, silver, aluminum and ITO.

[0038] According to some embodiments of the present application, the second conductive layer has a thickness of 20-50 nm. For example, it can be specifically 20-30 nm. It can be further specifically about 25 nm.

[0039] According to some embodiments of the present application, the ultra-flexible friction sensor further comprises a packaging layer, which is arranged on the side surface of the second conductive layer away from the substrate.

[0040] According to some embodiments of the present application, the packaging layer is a water-oxygen resistant material.

[0041] According to some embodiments of the present application, the material of the packaging layer comprises at least one of parylene and fluorinated polymer.

[0042] According to some embodiments of the present application, the packaging layer has a thickness of 0.1-2 μm. For example, it can be specifically about 1 μm.

[0043] According to some embodiments of the present application, the ultra-flexible friction sensor further comprises an external signal transmission line.

[0044] According to some embodiments of the present application, the number of external signal transmission lines is ≥2.

[0045] According to some embodiments of the present application, the external signal transmission line is electrically connected with the first conductive layer and / or the second conductive layer.

[0046] According to some embodiments of the present application, the material of the external signal transmission line comprises copper.

[0047] According to some embodiments of the present application, the ultra-flexible friction sensor has a thickness of 30-35 μm.

[0048] According to some embodiments of the present application, the ultra-flexible friction sensor comprises, which are arranged in sequence:

[0049] an adhesive layer, the material of which comprises a breathable hydrogel;

[0050] a sensing layer, which comprises, arranged in sequence from the adhesive layer, a substrate, a first conductive layer, a photoresist layer, an insulating polymer layer and a second conductive layer;

[0051] a packaging layer, the material of which is a water-oxygen resistant material;

[0052] The ultra-flexible friction sensor has a thickness of 20-40 μm.

[0053] According to some embodiments of the second aspect of the present application, a preparation method of the ultra-flexible friction sensor is provided, which comprises the following steps:

[0054] S1. depositing to prepare the substrate, and sequentially disposing the first conductive layer and the photoresist layer on the surface of the substrate to obtain a component A;

[0055] depositing the second conductive layer on the surface of the insulating polymer layer to obtain a component B;

[0056] S2. aligning and adhering the photoresist layer in the component A and the insulating polymer layer in the component B.

[0057] According to the preparation method of the embodiment of the present application, at least the following beneficial effects are achieved:

[0058] In the preparation method provided by the present application, the preparation of the sensing layer is similar to the preparation of a sandwich (the sensing layer has a sandwich-like structure), and only simple attachment is required, which is easy to implement and thus facilitates large-scale industrial promotion.

[0059] The substrate is prepared by deposition in the present application, so that the thickness of the substrate can be reduced and accurately adjusted. That is, the adjustment of the preparation method provided by the present application obtains an ultra-flexible friction sensor with better flexibility and higher sensitivity.

[0060] According to some embodiments of the present application, the method for disposing the component A further comprises disposing a sacrificial layer on the surface of a temporary substrate before disposing the substrate; and the substrate is disposed on the surface of the sacrificial layer. Since the thickness of the substrate is relatively thin and is not easy to form support, the substrate needs to be disposed on the surface of the temporary substrate. The temporary substrate is a rigid temporary substrate.

[0061] According to some embodiments of the present application, the rigid temporary substrate needs to be cleaned and dried before use. The cleaning includes ultrasonic cleaning with acetone / isopropyl alcohol / water in sequence. The drying includes blowing dry with a dust-free gas. The dust-free gas includes at least one of nitrogen, argon and air.

[0062] According to some embodiments of the present application, the material of the sacrificial layer includes a fluorine-containing compound. The advantage of using the sacrificial layer is that it can optimize the surface energy and surface state of the rigid temporary substrate, reduce the binding force between the flexible structure grown later and the rigid substrate, and at the same time ensure the integrity and peelability of the flexible structure in the subsequent repeated high-vacuum environment.

[0063] The fluorine-containing compound includes at least one of perfluoroalkane, perfluorosilane and fluorine-containing acrylic polymer.

[0064] According to some embodiments of the present application, the method for disposing the sacrificial layer includes coating. Specifically, it can be spin coating.

[0065] Specifically, the solution of the fluorine-containing compound is spin-coated on the surface of the rigid substrate. The spin-coating speed is about 3000 rpm and the time is about 30 s. The solution of the fluorine-containing compound can be self-made or commercially available.

[0066] According to some embodiments of the present application, the deposition method of the substrate comprises a chemical vapor deposition method. In the process, the p-xylylene dimer is first converted into molecules by thermal cracking, and then grown in a vacuum deposition chamber to form a p-xylylene layer. The thickness of the p-xylylene film can be adjusted by adjusting the amount of the reactant of the p-xylylene dimer. Using this preparation method, a large-area dense substrate layer can be formed.

[0067] According to some embodiments of the present application, in step S1, the method for setting the first conductive layer comprises at least one of sputtering and evaporation. The sputtering comprises at least one of magnetron sputtering.

[0068] In the radio frequency sputtering, the sputtering power is 50 W to 100 W, and the time is 10 to 20 min. For example, it can be about 15 min.

[0069] According to some embodiments of the present application, in step S1, the method for setting the photoresist layer comprises spin-coating, exposure and development performed in sequence.

[0070] The spin-coating speed of the pre-spinning is 400 to 600 rpm, for example, it can be about 500 rpm.

[0071] The time of the pre-spinning is 8 to 12 s, for example, it can be about 10 s.

[0072] The spin-coating speed of the post-spinning is 2500 to 3500 rpm, for example, it can be about 3000 rpm.

[0073] The time of the post-spinning is 20 to 40 s, for example, it can be about 30 s.

[0074] The exposure dose is 70 to 90 mJ / cm 2 , for example, it can be about 80 mJ / cm 2 .

[0075] The time of the exposure is 20 to 40 s, for example, it can be about 30 s.

[0076] The method for setting the photoresist layer further comprises baking before and after the exposure.

[0077] The baking temperature is 90 to 100℃, for example, it can be about 95℃.

[0078] The baking time is 1-5 minutes, for example, specifically about 3 minutes.

[0079] The exposure is performed with the aid of a mask, thereby a hollow pattern can be set on the photoresist layer. The pattern of the mask determines the shape, size, etc. of the hollow pattern.

[0080] According to some embodiments of the present application, in step S1, the method for setting the second conductive layer comprises at least one of sputtering and evaporation. The sputtering comprises magnetron sputtering. The magnetron sputtering comprises radio frequency sputtering.

[0081] The method for setting the second conductive layer and the first conductive layer can be the same or different. If the same radio frequency sputtering is adopted, the thickness of the obtained conductive layer is adjusted by adjusting the sputtering time.

[0082] According to some embodiments of the present application, in step S2, the bonding is completed by means of an adhesive. Specifically, the adhesive only bonds the edge positions of the component A and the component B. The adhesive comprises at least one of glue and adhesive tape.

[0083] According to some embodiments of the present application, in step S2, the method further comprises setting the external signal transmission line. The setting of the external signal transmission line is completed before the bonding; and / or, the setting of the external signal transmission line is completed after the bonding.

[0084] The method for setting the external signal transmission line comprises bonding by means of the adhesive.

[0085] According to some embodiments of the present application, in step S2, the method further comprises peeling off the temporary substrate after the bonding. Thereby, a super-flexible sensing layer is obtained.

[0086] According to some embodiments of the present application, the preparation method further comprises packaging after step S2. Thereby, the effects of isolating water and oxygen and external pollutants are achieved.

[0087] The packaging is performed by means of a coating instrument; specifically, a chemical vapor deposition coating instrument can be adopted.

[0088] According to some embodiments of the present application, the preparation method further comprises assembling the component obtained in step S2 and an adhering layer. Thereby, the super-flexible friction sensor can be attached to any desired position, and perfect bonding is achieved, and finally high-sensitivity monitoring of motion signals is realized.

[0089] Specifically, the adhering layer is arranged on the surface of the substrate away from the packaging layer.

[0090] According to the embodiment of the third aspect of the present application, there is provided a motion sensing system comprising the ultra-flexible friction sensor.

[0091] Since the motion sensing system adopts all the technical solutions of the ultra-flexible friction sensor of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments. That is, it has higher sensitivity and wearing comfort.

[0092] The motion sensing system can be used for capturing and monitoring human electromechanical signals.

[0093] The motion sensing system can be used for preparing a wearable health monitoring device.

[0094] According to the embodiment of the third aspect of the present application, there is provided an application of the ultra-flexible friction sensor in human motion signal detection.

[0095] Since the application adopts all the technical solutions of the ultra-flexible friction sensor of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments.

[0096] According to some embodiments of the present application, the human motion includes at least one of blinking, lip speaking, finger joint bending, and pulse beating.

[0097] Unless otherwise specified, "about" in the present application actually means that the allowed error is within ±2%, for example, about 100 actually means 100±2%×100.

[0098] Unless otherwise specified, "between" in the present application includes the numbers, for example, "between 2-3" includes the end point values 2 and 3.

[0099] Other features and advantages of the present application will be set forth in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0100] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the description that follows, including the appended drawings, in which:

[0101] Figure 1 is a structural schematic diagram of the ultra-flexible friction sensor provided by the embodiment 1 of the present application;

[0102] Figure 2 is a partial process schematic diagram of the preparation method in the embodiment 2 of the present application;

[0103] Figure 3 is a structural schematic diagram of the intermediate component in the step S2 of the embodiment 2 of the present application;

[0104] Figure 4 is the apparent diagram of the super-flexible friction sensor provided by the embodiment 1 of the present application.

[0105] Figure 5 is the apparent diagram of the super-flexible friction sensor provided by the embodiment 1 of the present application and the effect diagram of being attached on the human body surface.

[0106] Figure 6 is the apparent diagram of the PET flexible friction sensor provided by the comparative example 1 of the present application and the effect diagram of being attached on the human body surface.

[0107] Figure 7 is the apparent diagram of the PET flexible friction sensor provided by the comparative example 2 of the present application and the effect diagram of being attached on the human body surface.

[0108] Figure 8 is the sensitivity comparison diagram of the super-flexible friction sensor provided by the embodiment 1 of the present application under the action force of 0.1N.

[0109] Figure 9 is the signal output diagram of the flexible friction sensor provided by the comparative example 1 of the present application under the action force of 0.5N.

[0110] Figure 10 is the signal output diagram of the flexible friction sensor provided by the comparative example 2 of the present application under the action force of 0.5N.

[0111] Figure 11 is the voltage output effect of the super-flexible friction sensor provided by the embodiment 1 of the present application under the specific external action.

[0112] Figure 12 is the voltage feedback result of the super-flexible friction sensor provided by the embodiment 1 of the present application under the different bending angles.

[0113] Figure 13 is the monitoring result of the super-flexible friction sensor provided by the embodiment 1 of the present application to the human body blinking movement.

[0114] Figure 14 is the monitoring result of the super-flexible friction sensor provided by the embodiment 1 of the present application to the human body joint movement.

[0115] Figure 15 is the monitoring result of the super-flexible friction sensor provided by the embodiment 1 of the present application to the human body pulse beat.

[0116] Reference signs:

[0117] adhesive layer 100;

[0118] The sensing layer 200, the substrate 210, the first conductive layer 220, the photoresist layer 230, the adhesive 240, the insulating polymer layer 250, and the second conductive layer 260;

[0119] The encapsulation layer 300;

[0120] The external signal transmission line 400. DETAILED DESCRIPTION

[0121] Embodiments of the present application are described in detail below with reference to examples thereof shown in the attached drawings, wherein the same or similar reference numerals are used throughout the drawings and identical or similar elements or elements having the same or similar functions are denoted by the same or similar reference numerals. The embodiments described below with reference to the drawings are exemplary and are intended only for the purpose of explaining the present application, and should not be construed as limiting the present application.

[0122] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc., is based on the orientation or position relationship shown in the drawings, and is only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as limiting the present application, which indicates or implies that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation.

[0123] In the description of the present application, if the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described as first, second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the order of indicated technical features.

[0124] In the description of the present application, unless otherwise explicitly limited, the words such as setting, mounting, connecting, etc. should be broadly understood, and those skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0125] Unless otherwise specified, the adhesive layer in the specific embodiment uses the preparation method of the peelable ultrathin hydrogel disclosed in CN113754897A.

[0126] Example 1

[0127] Reference Figure 1 The present embodiment provides a kind of super flexible friction sensor, specific structure includes sequentially superimposed arrangement:

[0128] The adhesive layer 100 includes breathable hydrogel, and the material is polyacrylamide / sodium alginate hydrogel; The thickness is 15 μm;

[0129] The sensing layer 200 comprises, in sequence from the self-adhesion layer 100, a substrate 210, a first conductive layer 220, a photoresist layer 230, an insulating polymer layer 250, and a second conductive layer 260; wherein:

[0130] The edges of the photoresist layer 230 and the insulating polymer layer 250 are bonded by the adhesive 240;

[0131] The substrate 210 is made of parylene, and has a thickness of 3 μm;

[0132] The first conductive layer 220 is made of ITO, and has a thickness of 20 nm;

[0133] The photoresist layer 230 is made of SU-8, and has a thickness of 600 nm; the photoresist layer 230 has a hollow pattern, and the area of the hollow pattern accounts for 0%, 9.4%, 16.5%, 23.6%, 30.7%, and 37.7% of the total area of the photoresist layer 230 (i.e., six groups of super-flexible friction sensors are provided in this example).

[0134] The adhesive 240 is made of PET glue;

[0135] The insulating polymer layer 250 is made of FEP, and has a thickness of about 12.5 μm;

[0136] The second conductive layer 260 is made of ITO, and has a thickness of 25 nm;

[0137] The packaging layer 300 is made of parylene, and has a thickness of 1 μm;

[0138] The external signal transmission line 400 is made of copper, and has a number of 2, one of which is electrically connected to the first conductive layer 220, and the other of which is electrically connected to the second conductive layer 260;

[0139] The super-flexible friction sensor has a thickness of 32.3 μm.

[0140] In Figure 1 In the drawings, Figure 1 The sizes of the layers shown in the drawings do not represent the actual size relationship between the layers.

[0141] Embodiment 2

[0142] The embodiment provides a preparation method of a super-flexible friction sensor, and specifically prepares the super-flexible friction sensor provided in Embodiment 1, and the specific steps are as follows:

[0143] S1. Preparing component A and component B.

[0144] The preparation of component A comprises the following steps:

[0145] D1. The rigid substrate was sequentially cleaned by ultrasonic cleaning with acetone / isopropyl alcohol / water, and then dried with a nitrogen gun;

[0146] A fluorine-containing sacrificial layer solution was spin-coated on the rigid substrate, and the sacrificial layer solution was prepared by mixing Delo series coating liquid and 3M Novec series fluorine-containing liquid in a volume ratio of 2:1. The spin-coating speed was 3000 rpm, and the time was 30 s.

[0147] D2. A parylene film coater was used to deposit a substrate with a material of parylene on the sacrificial layer by chemical vapor deposition. The deposition time was not limited, and the deposition was stopped as long as the corresponding thickness was obtained.

[0148] D2. A first conductive layer with an ITO material was sputtered on the substrate, specifically by a magnetron sputtering deposition method, further specifically by radio frequency sputtering, with a sputtering power of 50 W, a sputtering time of 15 min, and a thickness of about 20 nm.

[0149] D3. The photoresist was patterned on the first conductive layer to form a patterned intermediate layer by using a photolithography technology; specifically:

[0150] A negative SU-8 photoresist was spin-coated on the first conductive layer to form a completely covered photoresist layer, which included pre-spinning and post-spinning in sequence, with specific parameters of pre-spinning 500 rpm / 10 s and post-spinning 3000 rpm / 30 s;

[0151] The spin-coated photoresist layer was pre-baked on a 95°C hot plate for 3 min to remove part of the solvent;

[0152] The photoresist layer was patterned to form a patterned intermediate layer by using a designed mask plate (which can adjust the patterned density from 0% to 40%, and each mask plate corresponds to a batch of ultra-flexible friction sensors), with an exposure dose of 80 mJ / cm 2 and a time of 30 s;

[0153] The patterned photoresist layer was post-baked on a 95°C hot plate for 3 min to fix the patterned shape;

[0154] Finally, the patterned photoresist layer was immersed in SU-8 developing solution to remove the excess unexposed position, forming a photoresist layer with a specific hollow pattern.

[0155] The preparation of component B includes the following steps:

[0156] T1. An ITO conductive film was sputtered on the FEP film (insulating polymer layer) to prepare a second conductive layer; specifically, radio frequency sputtering in magnetron sputtering was used, with a sputtering power of 50 W, a sputtering time of 20 min, and a thickness of about 25 nm.

[0157] S2. The first conductive layer and the second conductive layer are respectively connected with the external signal transmission line by using PET adhesive glue; the photoresist layer of the component obtained in step D3 and the edge of the FEP film of the component obtained in step T1 are bonded and attached by using PET adhesive glue; before the attachment, the top view of the component obtained in step D3 coated with the PET adhesive glue is as shown in Figure 3 .

[0158] The rigid temporary substrate is peeled off to obtain the sensing layer.

[0159] S3. The packaging layer is prepared on the surface of the second conductive layer by using chemical vapor deposition; the adhesion layer is attached to the surface of the substrate to obtain the ultra-flexible friction nanosensor with high sensitivity, which can form perfect attachment on any surface.

[0160] The schematic diagram of part of the preparation process of the example is as shown in Figure 2 .

[0161] Comparative Example 1

[0162] This comparative example provides a friction sensor, which is different from Example 1 in that:

[0163] (1) The material of the substrate 210 is PET, and the thickness is 38 μm.

[0164] (2) The photoresist layer 230 is not included in this example.

[0165] The preparation method of the friction sensor in this comparative example is different from that of Example 2 in that step D3 is not included.

[0166] Comparative Example 2

[0167] This comparative example provides a friction sensor, which is different from Example 1 in that:

[0168] (1) The material of the substrate 210 is PET, and the thickness is 38 μm.

[0169] (2) The hollow area ratio of the photoresist layer 230 is set to 23.6%.

[0170] The friction sensor is prepared by using the method of Example 2.

[0171] Test Example

[0172] The first aspect of this example observes the appearance of the ultra-flexible friction sensor obtained in the example, and observes whether it can be well attached to the curved surface of the human body. The results show that no matter how much the area of the photoresist layer with the hollow pattern is, the ultra-flexible friction sensor prepared by the application is very thin, has high flexibility, and has good attachment to any curved surface of the human body; it is expected to be used for high-sensitivity detection of human motion signals. Specifically, the appearance of the ultra-flexible friction sensor and the attachment effect on the human body are as shown inFigures 4-5 As shown. However, if a traditional PET film is used as the substrate (Comparative Examples 1-2), the flexibility of the friction sensor decreases, resulting in poor adhesion to the skin; the adhesion effect is shown in the figure. Figures 6-7 As shown.

[0173] The second aspect of this example tests the motion detection performance of the ultra-flexible friction sensor obtained in the embodiment, specifically:

[0174] Under the same external conditions (an external force of 0.1 N applied using a pressure testing machine), the responsiveness of the friction sensor was tested. It was found that if the photoresist layer had a perforated pattern, the ultra-flexible friction sensor generated a higher voltage, indicating higher sensitivity. Specifically, when the perforated pattern accounted for 23.6% of the image, the voltage was approximately 0.6 V, which was twice as high as that of the ultra-flexible friction sensor without a perforated pattern. This demonstrates that the innovative design of the photoresist layer and the perforated pattern on it creates a gap between the first and second conductive layers, which helps to form a stable built-in electric field. When subjected to a small external force, the output signal is stronger, and the sensitivity is significantly improved. Specific results are as follows: Figure 8 As shown. However, if a traditional PET film layer is used as the substrate, in Comparative Example 1, when the same 0.1N external force as in the example is applied, the friction sensor shows almost no deformation, and the output voltage is 0V; when the external force is further increased to 0.5N, the friction sensor shows some deformation, but the output voltage is basically 0; this is mainly because the PET-based friction sensor obtained in Comparative Example 1 has poor flexibility and lacks an intermediate photoresist layer to effectively reduce charge neutralization, as shown in the output signal curve. Figure 9 As shown in the figure; in Comparative Example 2, there is almost no response to an applied force of 0.1N, and the output voltage changes by only 0.15V under an applied force of 0.5N. However, in the examples, the ultra-flexible sensors prepared under the embodiments show output voltage changes greater than 0.2V under an applied force of only 0.1N. Among them, the ultra-flexible sensor in the embodiment with a 23.6% hollow area has the highest output voltage, reaching 0.6V. Therefore, both Comparative Examples 1 and 2 fully demonstrate that the ultra-flexible sensors prepared in the embodiments are more flexible and have higher sensitivity, and the intermediate photoresist layer effectively reduces charge neutralization, further improving the device sensitivity; the test results of Comparative Example 2 are as follows. Figure 10 As shown.

[0175] The ultra-flexible friction sensor with a 23.6% open area photoresist layer, as described in Example 1, was further tested. The results show that the ultra-flexible friction sensor provided by this invention can sense external changes of 0.01N and bending changes of 1°, providing a possibility for detecting minute changes in human motion signals. Furthermore, the output voltage increases with the increase of the external change amplitude, thus providing a possibility for quantitative monitoring of motion signals. Specific test results are as follows...Figures 11-12 as shown.

[0176] The super-flexible friction sensor with a photoresist layer having a 23.6% hollow area in Example 1 was used to monitor human motion, and the blinking, pulse beating and joint movement of the human body were specifically monitored. The results showed that all had high sensitivity, indicating that the super-flexible friction sensor provided by the application not only has high sensitivity, but also has a wide application range (wide applicable motion amplitude), which provides a possibility for human health monitoring. The specific test results are shown in Figures 13-15 as shown.

[0177] In summary, the super-flexible friction sensor provided by the application significantly improves its sensitivity through structural design, which provides a possibility for human health monitoring, and is expected to have broad application prospects.

[0178] The embodiments of the application are described in detail above in combination with the drawings, but the application is not limited to the above embodiments, and various changes can be made within the knowledge range of those skilled in the art without departing from the purpose of the application. In addition, the embodiments of the application and the features in the embodiments can be combined with each other without conflict.

Claims

1. An ultra-flexible friction sensor, characterized in that, The super-flexible friction sensor comprises a sensing layer; The sensing layer comprises a substrate, a first conductive layer, a photoresist layer, an insulating polymer layer and a second conductive layer which are sequentially stacked; The substrate is made of parylene and has a thickness of 0.1-3 μm; The photoresist layer has a hollow pattern, and the area ratio of the hollow pattern to the photoresist layer is 5-40%; The edges of the photoresist layer and the insulating polymer layer are provided with adhesive; The super-flexible friction sensor has a thickness of 20-40 μm.

2. The ultra-flexible friction sensor of claim 1, wherein, The photoresist layer has a thickness of 500-1000 nm.

3. The ultra-flexible friction sensor of claim 2, wherein, The area ratio of the hollow pattern to the photoresist layer is 15-30%.

4. The ultra-flexible friction sensor of claim 1, wherein, The super-flexible friction sensor further comprises a packaging layer provided on the side surface of the second conductive layer away from the substrate.

5. The ultra-flexible friction sensor of claim 4, wherein, The packaging layer has a thickness of 0.1-2 μm.

6. The ultra-flexible friction sensor of claim 1, wherein, The super-flexible friction sensor further comprises an adhesive layer provided on the side surface of the substrate away from the second conductive layer; and / or, the adhesive layer is made of breathable hydrogel.

7. The ultra-flexible friction sensor according to any one of claims 1-6, wherein, The insulating polymer layer is made of FEP, and / or has a thickness of 10-15 μm.

8. A method of manufacturing the ultra-flexible friction sensor according to any one of claims 1 to 7, characterized in that, The preparation method comprises the following steps: S1. depositing the substrate, and sequentially arranging the first conductive layer and the photoresist layer on the surface of the substrate to obtain a component A; depositing the second conductive layer on the surface of the insulating polymer layer to obtain a component B; S2. aligning and adhering the photoresist layer in the component A and the insulating polymer layer in the component B.

9. The production method according to claim 8, characterized by, The preparation method further comprises packaging after step S2; and / or, the preparation method further comprises assembling the component obtained in step S2 and the adhesive layer.

10. A motion sensing system characterized by, The motion sensing system comprises the super-flexible friction sensor according to any one of claims 1-7.

11. Use of the super-flexible friction sensor according to any one of claims 1-7 in detection of human motion signals.

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