A flexible transparent electrode and preparation method thereof

Abstract

The invention discloses a flexible transparent electrode and a preparation method thereof. The preparation method of the flexible transparent electrode comprises: disposing a biocompatible adhesive on a hard substrate to form a thin film adhesive layer; disposing a biocompatible thin film material with flexibility and insulation on the thin film adhesive layer to form a thin film insulating layer; disposing a transparent biocompatible photoresist on the thin film insulating layer to form a photolithographic adhesive layer; disposing a conductive material and a pattern photoresist on the photolithographic adhesive layer in sequence, and performing photolithography, development and etching operations in sequence to form a conductive layer with a preset electrode pattern; disposing the transparent biocompatible photoresist on the conductive layer, and opening a window above the electrode site in the conductive layer to form a packaging layer with the window; peeling the thin film insulating layer from the hard substrate to form a flexible transparent electrode. The invention solves the problems of opacity, chemical corrosion resistance and short service life of traditional electrodes caused by rigidity.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible electrodes, and in particular to a flexible transparent electrode and a preparation method thereof. Background Art

[0002] In the field of modern electronic devices and micro-biosensors, the role of micro-electrode arrays is becoming more and more extensive. On the one hand, the large-scale popularization of modern intelligent wearable electronic devices has led to the development of flexibility and miniaturization, so the application scope of flexible micro-electrode arrays is becoming more and more extensive; on the other hand, in the field of biomedical research, in order to achieve cell-level monitoring and stimulation and monitor electrophysiological signals, the demand for micro-electrodes is also increasing day by day.

[0003] Traditional electrode materials are mostly metal-based, but metals have poor flexibility and are often used on traditional rigid electrodes. They are also very easy to break during stretching and bending, so they are difficult to use in flexible microelectrodes. In the biomedical field, the characteristics of flexible devices are needed to give full play to their advantages of flexible deployment, adapt to different working environments, and fit closely with biological tissues, thereby inhibiting or even avoiding rejection reactions. However, electrodes made of metal materials are easily damaged by mechanical fracture, chemical corrosion, etc., and it is difficult to meet the needs of practical applications; in addition, traditional metal electrodes do not have the characteristics of transparency, and it is difficult to observe the specific reaction at the contact site of the electrode. Therefore, those skilled in the art are in urgent need of an electrode that is both flexible and transparent to meet application requirements. Summary of the invention

[0004] The purpose of the present invention is to provide a flexible transparent electrode and a preparation method thereof, which solves the problems of poor versatility, opacity, chemical corrosion resistance and short service life of traditional microelectrodes due to rigidity.

[0005] As one aspect of the present invention, the present invention provides a method for preparing a flexible transparent electrode, the method comprising:

[0006] deploying a biocompatible adhesive on a rigid substrate to form a thin film adhesive layer;

[0007] Disposing a biocompatible thin film material having flexibility and insulation properties on the thin film adhesive layer to form a thin film insulation layer;

[0008] disposing a transparent biocompatible photoresist on the thin film insulating layer to form a photolithographic adhesion layer;

[0009] Disposing a conductive material and a patterned photoresist on the photolithographic adhesive layer in sequence, and performing photolithography, development and etching operations in sequence to form a conductive layer having a preset electrode pattern;

[0010] Disposing the transparent biocompatible photoresist on the conductive layer, and opening windows above the electrode sites in the conductive layer to form a packaging layer with windows;

[0011] The thin film insulating layer is peeled off from the hard substrate to form a flexible transparent electrode including the thin film insulating layer, the photolithography adhesive layer, the conductive layer and the encapsulation layer.

[0012] Optionally, the step of disposing a transparent biocompatible photoresist on the thin film insulating layer to form a photolithography adhesion layer specifically includes:

[0013] sequentially heating and exposing the transparent biocompatible photoresist disposed on the thin film insulating layer to form a semi-cured photoresist bonding layer;

[0014] The step of sequentially disposing a conductive material and a patterned photoresist on the photoresist bonding layer specifically includes:

[0015] disposing a conductive ink on the semi-cured photolithographic adhesive layer;

[0016] Heat treatment to form the conductive ink into a cured conductive material and to form the semi-cured photoresist adhesive layer into a cured photoresist adhesive layer; wherein the conductive material is semi-embedded in the cured photoresist adhesive layer;

[0017] The patterned photoresist is disposed on the conductive material.

[0018] Optionally, after disposing the transparent biocompatible photoresist on the conductive layer and opening a window above the electrode site in the conductive layer to form a packaging layer with a window, the method further comprises:

[0019] When the conductive material is a metal material, an electroplating process is performed to form an electroplating layer located above the electrode site in the conductive layer at the opening of the encapsulation layer;

[0020] At this time, the prepared flexible transparent electrode includes: the thin film insulating layer, the photolithography adhesive layer, the conductive layer, the encapsulation layer and the electroplating layer.

[0021] Optionally, the biocompatible adhesive is polydimethylsiloxane (PDMS) or polyurethane elastomer (TPU).

[0022] Optionally, the biocompatible film material with flexibility and insulation properties is one of the following: polyethylene terephthalate PET, polyparaxylene Parylene, and polyimide PI.

[0023] Optionally, the transparent biocompatible photoresist is one of the following: SU-8 photoresist, acrylate photoresist, IP-PDMS photoresist, and hydrogel photoresist.

[0024] Optionally, the conductive material is: metal nanowires or carbon nanotubes.

[0025] Optionally, the pattern photoresist is: AZ2070 or AZ4620.

[0026] As another aspect of the present invention, the present invention further provides a flexible transparent electrode, which is prepared by any one of the above-mentioned methods for preparing a flexible transparent electrode.

[0027] As another aspect of the present invention, the present invention also provides a flexible transparent electrode, comprising:

[0028] A flexible thin film insulating layer for supporting the flexible transparent electrode;

[0029] A transparent photolithography adhesive layer located on the thin film insulating layer;

[0030] A conductive layer having a preset electrode pattern, half-embedded in the upper surface of the photolithography adhesive layer;

[0031] A transparent encapsulation layer, located on the conductive layer and in contact with the photolithography adhesive layer;

[0032] The photolithography bonding layer is made of the same material as that used for the packaging layer, and the packaging layer has a window located above the electrode site in the conductive layer.

[0033] The flexible transparent electrode and preparation method provided by the present invention can produce a kind of electrode that allows light to pass through while playing the function of a traditional electrode (such as receiving and transmitting electrical signals), so as to facilitate observation of tissues in the body through the electrode to achieve the purpose of precise positioning and observation feedback. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0035] Figure 1 An optional schematic flow chart of the method for preparing a flexible transparent electrode provided in Example 1;

[0036] Figure 2 A schematic diagram of an electrode structure formed in the process of preparing a flexible transparent electrode provided in Example 1;

[0037] Figure 3 A schematic diagram of the top view structure of the prepared flexible transparent electrode provided in Example 1;

[0038] Figure 4 This is a schematic diagram of the composition structure of the flexible transparent electrode provided in Example 3. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] Embodiment 1

[0041] The present invention provides a method for preparing a flexible transparent electrode. Figure 1 As shown, the method specifically comprises the following steps:

[0042] Step S102: deploying a biocompatible adhesive on the hard substrate to form a thin film adhesive layer.

[0043] The purpose of using the hard substrate is to provide support for the flexible part formed subsequently to facilitate subsequent operations; preferably, the hard substrate is: glass or silicon wafer; of course, in practical applications, the hard substrate can also be made of other hard materials, which is not specifically limited here.

[0044] Specifically, the step S102 includes:

[0045] A biocompatible adhesive is spin-coated on a rigid substrate to form a thin film adhesive layer for attaching a thin film insulating layer.

[0046] Among them, Figure 2 As shown, the thin film adhesive layer is used to adhere to the subsequently formed thin film insulating layer, so as to fix the subsequently formed flexible part on the hard substrate; preferably, the biocompatible adhesive is: polydimethylsiloxane PDMS or polyurethane elastomer TPU; of course, in practical applications, the biocompatible adhesive can also use any other material for bonding purposes that is not prone to cause biological rejection and is non-toxic and harmless to organisms, and no specific limitation is made here.

[0047] Step S104: disposing a biocompatible thin film material having flexibility and insulation properties on the thin film adhesive layer to form a thin film insulation layer.

[0048] In this embodiment, after the flexible transparent electrode is formed on the hard substrate, the formed flexible transparent electrode is peeled off from the hard substrate, and the bottom layer of the peeled flexible transparent electrode is the thin film insulating layer, so that the formed flexible transparent electrode can receive and transmit electrical signals.

[0049] Preferably, the biocompatible film material having flexibility and insulation properties is one of the following: polyethylene terephthalate PET, polyparaxylene Parylene, polyimide PI.

[0050] Specifically, after step S104, the method further includes:

[0051] Step S105: heat-treating the portion consisting of the hard substrate, the thin film adhesive layer and the thin film insulating layer to cure the thin film adhesive layer, so that the thin film insulating layer is fixed on the hard substrate through the cured thin film adhesive layer.

[0052] Step S106: disposing a transparent biocompatible photoresist on the thin film insulating layer to form a photoresist adhesion layer.

[0053] Preferably, the transparent biocompatible photoresist is one of the following: SU-8 photoresist, acrylate photoresist (for example, PMMA photoresist), IP-PDMS photoresist, hydrogel photoresist; of course, in practical applications, the transparent biocompatible photoresist can also be any material that is not prone to causing biological rejection, is non-toxic and harmless to organisms, and has insulation and photocuring properties similar to photoresist, and is not specifically limited here.

[0054] Specifically, the step S106 includes:

[0055] Spin coating the transparent biocompatible photoresist on the thin film insulating layer;

[0056] The transparent biocompatible photoresist disposed on the thin film insulating layer is subjected to heat treatment and exposure to form a semi-cured photoresist adhesion layer.

[0057] In this embodiment, the semi-cured photoresist adhesive layer can assist in fixing the conductive material used subsequently. Preferably, the heat treatment is first performed at a low temperature, and then the photoresist is exposed to near-ultraviolet light with a dose of less than or equal to 80 to form an incompletely cured photoresist adhesive layer.

[0058] Step S108: sequentially disposing a conductive material and a patterned photoresist on the photoresist bonding layer, and sequentially performing photolithography, development and etching operations to form a conductive layer having a preset electrode pattern.

[0059] Specifically, the conductive material and the pattern photoresist are disposed on the photolithography adhesive layer in sequence, including:

[0060] Step A1: deploying conductive ink on the semi-cured photolithography adhesive layer;

[0061] The conductive ink is disposed on the semi-cured photoresist adhesive layer by spin coating, the purpose of which is to evenly deploy the conductive ink, and the deployment method can also be spraying or the like under the premise of ensuring uniformity. Preferably, the conductive ink is: an IPA isopropyl alcohol solution of metal nanowires (e.g., silver nanowires).

[0062] Step A2: heating the conductive ink to form a solidified conductive material, and the semi-solidified photoresist adhesive layer to form a solidified photoresist adhesive layer; wherein the conductive material is semi-embedded in the solidified photoresist adhesive layer;

[0063] Preferably, the conductive material is silver nanowire. Of course, in practical applications, the conductive material may also be other metal nanowires or carbon nanotubes, which are not specifically limited here.

[0064] Step A3: disposing the pattern photoresist on the conductive material;

[0065] Preferably, the pattern photoresist is: AZ2070 or AZ4620.

[0066] Furthermore, the sequentially performing photolithography, development and etching operations to form a conductive layer having a preset electrode pattern specifically includes:

[0067] Step A4: heating the pattern photoresist to obtain a dried pattern photoresist;

[0068] Step A5: exposing the dried patterned photoresist using a photolithography machine and a preset mask;

[0069] Step A6: developing the exposed pattern photoresist with a developer to remove unnecessary pattern photoresist, and the remaining pattern photoresist forms a preset electrode pattern;

[0070] It should be noted that in actual applications, a corresponding mask is selected according to whether the pattern photoresist used is a positive photoresist or a negative photoresist, so that the required pattern photoresist portion is retained in the development operation;

[0071] Step A7: removing the conductive material not covered by the retained pattern photoresist by an etchant, and the retained conductive material is protected by the pattern photoresist;

[0072] In this embodiment, the conductive material not protected by the pattern photoresist is removed by etching, and the remaining conductive material constitutes a preset electrode pattern;

[0073] Step A8: removing the retained pattern photoresist by a cleaning agent to form a conductive layer composed of retained conductive material;

[0074] In this embodiment, the pattern photoresist remaining on the conductive material is removed by a cleaning operation to obtain a conductive layer having a preset electrode pattern formed by the remaining conductive material.

[0075] Conductive ink (ie, conductive material) is spin-coated on the photolithography adhesive layer to ensure that the prepared flexible transparent electrode has basic conductivity. The conductive material is photolithographically processed and developed to obtain the desired pattern and quantity to obtain a conductive layer containing a microelectrode array.

[0076] Step S110: disposing the transparent biocompatible photoresist on the conductive layer, and opening windows above the electrode sites in the conductive layer to form a packaging layer with windows.

[0077] The photolithography adhesive layer and the packaging layer are made of the same material.

[0078] Specifically, a window is opened above the electrode site in the conductive layer to form a packaging layer with a window, such as Figure 2 As shown, including:

[0079] A photolithography machine and the preset mask are used to remove the deployed transparent biocompatible photoresist located above the electrode sites in the conductive layer to form windows, thereby obtaining a packaging layer with windows.

[0080] Through the above steps, the areas other than the electrode working area (i.e., the electrode sites) can be made insulating. Figure 3 As shown, it is only necessary to form windows above the electrode site area in the conductive layer, while other areas (such as the wire area) do not need to form windows.

[0081] In addition, by using transparent biocompatible photoresist, the prepared electrodes can have good transparency, thereby achieving the function of observing the corresponding electrode sites while conducting electricity.

[0082] like Figure 2 As shown, during the preparation process, the following layers are formed in sequence on the hard substrate: a thin film bonding layer, a thin film insulating layer, a photolithography bonding layer, a conductive layer, and a packaging layer with openings.

[0083] Step S112: peeling the thin film insulating layer from the hard substrate to form a flexible transparent electrode comprising the thin film insulating layer, the photolithography adhesive layer, the conductive layer and the encapsulation layer.

[0084] Specifically, in step S112, the thin film adhesive layer may be peeled off so that the thin film insulating layer and the flexible portion thereon are peeled off from the hard substrate.

[0085] Furthermore, after step S110, the method further includes:

[0086] Step S111, when the conductive material is a metal material, electroplating is performed to form an electroplating layer located above the electrode sites in the conductive layer at the openings of the packaging layer.

[0087] In this embodiment, when the conductive material is a metal nanowire (for example, a silver nanowire), the above step S111 is performed, but when the conductive material is a carbon nanotube, the above step S111 is not performed; the electroplating step of step S111 can enhance the chemical stability of the prepared flexible transparent electrode, making it more suitable for long-term use in a living body.

[0088] When the conductive material is a metal material, the prepared flexible transparent electrode includes: the thin film insulating layer, the photolithography adhesive layer, the conductive layer, the packaging layer and the electroplating layer.

[0089] In this embodiment, a micro-electrode having both flexibility and transparency is prepared by using transparent materials. The prepared flexible transparent electrode includes at least from bottom to top: a thin film insulating layer for supporting, a transparent photolithography bonding layer, a conductive layer having a preset electrode pattern semi-embedded on the upper surface of the photolithography bonding layer, and a transparent encapsulation layer having the same material as the photolithography bonding layer for encapsulating the conductive layer, and the encapsulation layer has a window located above the electrode site in the conductive layer. In addition, in order to enhance the chemical stability of the prepared flexible transparent electrode, when the conductive layer uses a metal material, an electroplating operation is required, and an electroplating layer covering the electrode site is formed at the window of the encapsulation layer. When the prepared flexible transparent electrode is used, the encapsulation layer is attached to the organ of the organism to detect and transmit electrical signals through the electrode site in the conductive layer. The flexible transparent electrode prepared by this embodiment can not only detect and transmit signals to the organs of the organism, but also observe the tissues in the organism through the transparent electrode to achieve the purpose of precise positioning and observation feedback.

[0090] Embodiment 2

[0091] An embodiment of the present invention provides a method for preparing a flexible transparent electrode, the method specifically comprising the following steps:

[0092] Step S201: Select a hard substrate as a carrier.

[0093] Preferably, the hard substrate is made of glass or silicon wafer.

[0094] Step S202: Mix the main agent and curing agent of PDMS in a weight ratio of 10:1, perform vacuum degassing after mixing evenly to obtain PDMS adhesive, and use a spin coating bucket to spin coat the PDMS adhesive on the hard substrate to form a thin film adhesive layer.

[0095] Wherein, in step S202, the parameters of the spin coating barrel are set as: rotation speed 2000 rpm, acceleration 500 acc, and working time 40 s.

[0096] In this embodiment, since the prepared electrode is flexible, a hard substrate is required to support the flexible material used in the process of preparing the flexible electrode. In addition, in this embodiment, a thin film adhesive layer formed of PDMS is used to fix the flexible material used in the process of preparing the flexible electrode on the hard substrate.

[0097] Step S203: obtaining a PET film, laminating the PET film on the film adhesive layer, and removing bubbles between the PET film and the film adhesive layer.

[0098] In practical applications, the hard substrate with the thin film adhesive layer spin-coated thereon can be taken out from the spin coating barrel, and a layer of PET film can be laid flat on the thin film adhesive layer; the PET film is the lowest layer of the prepared flexible transparent electrode.

[0099] Step S204: placing the hard substrate having the thin film adhesive layer and the PET film on a heating plate, and baking at 70° C. for 2 hours to cure the thin film adhesive layer.

[0100] The PET film is fixed on the hard substrate by curing the film adhesive layer.

[0101] Step S205: plasma cleaning the manufactured part, specifically: cleaning with oxygen ions at 100 watts for 3 minutes and cooling.

[0102] Step S206: spin-coating SU-8 photoresist on the PET film using a spin coating bucket.

[0103] Wherein, in step S206, the parameters of the spin coating barrel are set as: rotation speed 3000 rpm, acceleration 500 acc, and working time 40 s.

[0104] Step S207: Perform an incomplete curing operation on the spin-coated SU-8 photoresist to obtain a semi-cured SU-8 photoresist layer, specifically: ① first bake the spin-coated SU-8 photoresist at 65°C for 120s, and then bake it at 95°C for 120s to complete the pre-bake; ② first use a photolithography machine and a photolithography process to expose the pre-baked SU-8 photoresist under 80 doses of near-ultraviolet, and then bake it at 95°C for 120s to complete the post-bake, thereby obtaining a semi-cured SU-8 photoresist layer.

[0105] In this embodiment, the spin-coated SU-8 photoresist is baked at a low temperature and exposed to a small dose to allow the spin-coated SU-8 photoresist to reach an incompletely cured state, thereby facilitating the subsequent semi-embedding of silver nanowires on the upper surface of the SU-8 photoresist.

[0106] Step S208: plasma cleaning the manufactured part, specifically: cleaning with oxygen ions at 100 watts for 3 minutes and cooling.

[0107] Step S209: taking a silver nanowire IPA solution with a length of 40 μm, a diameter of 100 nm and a concentration of 4 mg / ml, and using an ultrasonic disperser to ultrasonically disperse the silver nanowire IPA solution for 3 seconds.

[0108] By using an ultrasonic disperser, the silver nanowire IPA solution is in a suspension state, thereby facilitating the subsequent spin coating step.

[0109] Step S210: spin-coating the ultrasonically dispersed silver nanowire IPA solution onto the semi-cured SU-8 photoresist layer using a spin coating bucket.

[0110] Wherein, in step S210, the parameters of the spin coating barrel are set as: rotation speed 1000 rpm, acceleration 500 acc, and working time 20 s.

[0111] Specifically, a hard substrate having a thin film adhesive layer, a PET film and a semi-cured SU-8 photoresist layer is placed in a spin coating bucket, and after the spin coating bucket starts to rotate, 0.15 ml (3 drops) of silver nanowire IPA solution is dripped into it to spin coat the silver nanowire IPA solution on the incompletely cured SU-8 photoresist layer.

[0112] Step S211: placing the hard substrate on a heating plate, using the heating plate, first baking at 95°C for 60s, and then baking at 110°C for 120s, so that the liquid in the silver nanowire IPA solution evaporates to obtain solidified silver nanowires with an irregular grid shape, and a completely solidified SU-8 photoresist layer; at this time, the silver nanowires are half-embedded in the upper surface of the solidified SU-8 photoresist layer.

[0113] In this embodiment, the mesh structure of silver nanowires is used, and the silver nanowires in the mesh structure are semi-embedded in a transparent SU-8 photoresist, thereby preparing a transparent electrode.

[0114] Step S212: using a spin coating bucket to spin-coat AZ2070 photoresist onto the silver nanowires.

[0115] Wherein, in step S212, the parameters of the spin coating barrel are set to: rotation speed 3000 rpm, acceleration 500 acc, and working time 40 s.

[0116] Step S213: soft-baking the spin-coated AZ2070 photoresist for 180 seconds at 110° C. to obtain a dry AZ2070 photoresist.

[0117] Step S214: first use a photolithography machine and a mask with a preset electrode pattern to expose the dried AZ2070 photoresist under 60 doses of near-ultraviolet light, and then post-bake at 110° C. for 210 seconds.

[0118] Step S215: performing a developing operation in a 300 MIF developer to remove the unexposed AZ2070 photoresist, and the remaining exposed AZ2070 photoresist forms a preset electrode pattern.

[0119] It should be noted that since AZ2070 photoresist is a negative photoresist, during the exposure process, the exposed area will undergo chemical changes and become insoluble in the developer, while the unexposed area will remain unchanged and be dissolved during the development process. Therefore, during the development process, the AZ2070 photoresist in the exposed area is retained, while the AZ2070 photoresist in the unexposed area is removed, thereby forming the desired electrode pattern.

[0120] In addition, when AZ4620 is used as the photoresist, the mask used is different from the mask used in step S214; since AZ4620 is a positive photoresist, during the exposure process, the unexposed area remains unchanged, while the exposed area undergoes chemical changes after exposure, such as photodecomposition reaction, and becomes soluble in the developer. Therefore, during the development process, the AZ4620 photoresist in the exposed area is dissolved, while the AZ4620 photoresist in the unexposed area is retained, thereby forming the desired electrode pattern.

[0121] Step S216: Immersing in a silver etchant to remove the silver nanowires that are not protected by the cured AZ2070 photoresist.

[0122] Through etching operation, the silver nanowires not protected by the photoresist are removed, and the retained silver nanowires form a preset electrode pattern.

[0123] Step S217: Immersing in a stripping agent to remove the remaining cured AZ2070 photoresist on the remaining silver nanowires, thereby obtaining a conductive layer composed of silver nanowires with a preset electrode pattern.

[0124] Through the above steps S212 to S217, a conductive layer composed of silver nanowires and having a preset electrode pattern is formed on the cured SU-8 photoresist layer, thereby ensuring that the prepared flexible transparent electrode has basic conductivity.

[0125] Step S218: spin-coating SU-8 photoresist on the conductive layer using a spin coating bucket, and performing a pre-baking operation.

[0126] Wherein, in step S218, the parameters of the spin coating barrel are set as: rotation speed 3000 rpm, acceleration 500 acc, and working time 40 s.

[0127] Step S219: using a photolithography machine and the mask to expose the SU-8 photoresist on the conductive layer to remove the SU-8 photoresist located above the electrode sites in the conductive layer to form windows.

[0128] Through the above step S2019, other areas except the electrode working area (ie, the electrode site) can be made insulating.

[0129] Step S220: performing post-baking and developing operations to form a packaging layer with windows on the conductive layer.

[0130] Step S221: immersing in a plating solution to perform gold electroplating to form an electroplating layer located above the electrode sites in the conductive layer at the openings of the packaging layer.

[0131] The electroplating step in step S221 can enhance the chemical stability of the prepared flexible transparent electrode, making it more suitable for long-term use in a living body.

[0132] Step S222: peeling off the film adhesive layer to separate the PET film from the hard substrate, thereby obtaining a flexible transparent electrode.

[0133] The flexible transparent electrode prepared through the above steps S201 to S222 includes: a PET film, a SU-8 photoresist layer, a conductive layer composed of silver nanowires, a packaging layer formed by SU-8 photoresist, and an electroplating layer.

[0134] In this embodiment, the light transmittance of the mesh structure formed by the silver nanowires after uniform dispersion is cleverly utilized to prepare a transparent electrode that can visually observe the tested site (i.e., the electrode site), and the curing characteristics of the SU-8 photoresist are utilized to make the silver nanowires half-embedded in the SU-8 photoresist when it is not completely cured. After etching, the etched silver nanowires will leave mesh grooves on the SU-8 photoresist in which they are embedded, affecting the light transmittance. At this time, the SU-8 photoresist is used again for encapsulation. Since the same material is used, the mesh grooves are filled by the liquid SU-8 photoresist to form a microelectrode array film with high light transmittance. The microelectrode prepared by this embodiment can greatly improve the light transmittance of the electrode, which can reach 70%-80%. At the same time, the silver nanowire volatile solution is used as the conductive ink spin coating, the preparation process is relatively simple, the equipment requirements are relatively low, and the required micro flexible transparent electrode can be prepared quickly and at low cost.

[0135] Embodiment 3

[0136] The embodiment of the present invention provides a flexible transparent electrode obtained by the preparation method described in the first or second embodiment, such as Figure 4 As shown, the flexible transparent electrode includes the following components:

[0137] A flexible thin film insulating layer 401, used to support the flexible transparent electrode;

[0138] A transparent photolithography adhesive layer 402, located on the thin film insulating layer 401;

[0139] A conductive layer 403 having a preset electrode pattern, half-embedded in the upper surface of the photolithography adhesive layer 402;

[0140] A transparent encapsulation layer 404, located on the conductive layer 403 and in contact with the photolithography adhesive layer 402;

[0141] The photolithography bonding layer 402 is made of the same material as the packaging layer 404 , and the packaging layer 404 has a window located above the electrode site in the conductive layer 403 .

[0142] When the prepared flexible transparent electrode is used, the encapsulation layer 404 is attached to the biological organ to detect and transmit electrical signals through the electrode sites in the conductive layer 403 .

[0143] Specifically, the thin film insulating layer 401 is formed of a biocompatible thin film material with flexibility and insulation; preferably, the material used for the thin film insulating layer 401 is one of the following: polyethylene terephthalate PET, polyparaxylene Parylene, polyimide PI.

[0144] The photoresist bonding layer 402 and the encapsulation layer 404 are formed of transparent biocompatible photoresist; preferably, the material used for the photoresist bonding layer 402 and the encapsulation layer 404 is one of the following: SU-8 photoresist, acrylate photoresist (eg, PMMA photoresist), IP-PDMS photoresist, hydrogel photoresist.

[0145] The conductive layer 403 is formed by using a conductive material and a pattern photoresist, and performing photolithography, development and etching operations in sequence; preferably, the conductive material is a metal nanowire or a carbon nanotube, and the pattern photoresist is AZ2070 or AZ4620; that is, the material used for the conductive layer 403 is: a metal nanowire or a carbon nanotube. It should also be noted that in practical applications, silver nanowires are preferred because they have excellent conductivity, high flexibility, and are easy to combine with flexible materials; thanks to their various properties, the flexible electrode made based on silver nanowires has excellent performance.

[0146] Furthermore, when the material used for the conductive layer 403 is metal nanowires, the flexible transparent electrode further includes:

[0147] The electroplating layer 405 is located at the opening of the packaging layer 404 and covers the electrode sites in the conductive layer 403 .

[0148] The electroplating layer 405 can enhance the chemical stability of the flexible transparent electrode, making the flexible transparent electrode more suitable for long-term use in a living body.

[0149] The flexible transparent electrode provided in this embodiment can not only detect and transmit signals of biological organs, but also observe the tissues in the body through the transparent electrode to achieve the purpose of precise positioning and observation feedback, thus solving the problems of poor versatility, opacity, chemical corrosion resistance and short service life of traditional microelectrodes due to rigidity.

[0150] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0151] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0152] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method.

[0153] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a flexible transparent electrode, characterized in that: The method comprises: deploying a biocompatible adhesive on a rigid substrate to form a thin film adhesive layer; Disposing a biocompatible thin film material having flexibility and insulation properties on the thin film adhesive layer to form a thin film insulation layer; disposing a transparent biocompatible photoresist on the thin film insulating layer to form a photolithographic adhesion layer; Disposing a conductive material and a patterned photoresist on the photolithographic adhesive layer in sequence, and performing photolithography, development and etching operations in sequence to form a conductive layer having a preset electrode pattern; Disposing the transparent biocompatible photoresist on the conductive layer, and opening windows above the electrode sites in the conductive layer to form a packaging layer with windows; Peeling the thin film insulating layer off the hard substrate to form a flexible transparent electrode comprising the thin film insulating layer, the photolithography adhesive layer, the conductive layer and the encapsulation layer; Wherein, the step of disposing a transparent biocompatible photoresist on the thin film insulating layer to form a photolithography adhesive layer specifically includes: sequentially heating and exposing the transparent biocompatible photoresist disposed on the thin film insulating layer to form a semi-cured photoresist bonding layer; The step of sequentially disposing a conductive material and a patterned photoresist on the photoresist bonding layer specifically includes: disposing a conductive ink on the semi-cured photolithographic adhesive layer; Heat treatment to form the conductive ink into a cured conductive material and to form the semi-cured photoresist adhesive layer into a cured photoresist adhesive layer; wherein the conductive material is semi-embedded in the cured photoresist adhesive layer; The patterned photoresist is disposed on the conductive material.

2. The method for preparing a flexible transparent electrode according to claim 1, characterized in that: After disposing the transparent biocompatible photoresist on the conductive layer and opening windows above the electrode sites in the conductive layer to form a packaging layer with windows, the method further includes: When the conductive material is a metal material, an electroplating process is performed to form an electroplating layer located above the electrode site in the conductive layer at the opening of the encapsulation layer; At this time, the prepared flexible transparent electrode includes: the thin film insulating layer, the photolithography adhesive layer, the conductive layer, the encapsulation layer and the electroplating layer.

3. The method for preparing a flexible transparent electrode according to claim 1, characterized in that: The biocompatible adhesive is polydimethylsiloxane (PDMS) or polyurethane elastomer (TPU).

4. The method for preparing a flexible transparent electrode according to claim 1, characterized in that: The biocompatible film material with flexibility and insulation is one of the following: polyethylene terephthalate PET, polyparaxylene Parylene, polyimide PI.

5. The method for preparing a flexible transparent electrode according to claim 1, characterized in that: The transparent biocompatible photoresist is one of the following: SU-8 photoresist, acrylate photoresist, IP-PDMS photoresist, and hydrogel photoresist.

6. The method for preparing a flexible transparent electrode according to claim 1, characterized in that: The conductive material is: metal nanowire or carbon nanotube.

7. The method for preparing a flexible transparent electrode according to claim 1, characterized in that: The pattern photoresist is: AZ2070 or AZ4620.

8. A flexible transparent electrode, characterized in that: The flexible transparent electrode is prepared by the method for preparing a flexible transparent electrode according to any one of claims 1 to 7.

9. A flexible transparent electrode, characterized in that: include: A flexible thin film insulating layer for supporting the flexible transparent electrode; A transparent photolithography adhesive layer located on the thin film insulating layer; A conductive layer with a preset electrode pattern is semi-embedded in the upper surface of the photolithography adhesive layer; wherein the transparent biocompatible photoresist disposed on the thin film insulating layer is first subjected to heat treatment and exposure in sequence to form a semi-cured photolithography adhesive layer, and then a conductive ink is disposed on the semi-cured photolithography adhesive layer, and finally a heat treatment is performed to form the conductive ink into a cured conductive material and the semi-cured photolithography adhesive layer into a cured photolithography adhesive layer, so that the conductive layer is semi-embedded in the cured photolithography adhesive layer; A transparent encapsulation layer, located on the conductive layer and in contact with the photolithography adhesive layer; The photolithography bonding layer is made of the same material as that used for the packaging layer, and the packaging layer has a window located above the electrode site in the conductive layer.

Images