CN115590521A

CN115590521A - High-conductivity breathable hydrogel dry electrode and manufacturing method thereof

Info

Publication number: CN115590521A
Application number: CN202211612459.8A
Authority: CN
Inventors: 宾剑雄; 牛兰; 康晓洋; 张立华
Original assignee: Ji Hua Laboratory
Current assignee: Ji Hua Laboratory
Priority date: 2022-12-15
Filing date: 2022-12-15
Publication date: 2023-01-13
Anticipated expiration: 2042-12-15
Also published as: CN115590521B

Abstract

The invention discloses a high-conductivity breathable hydrogel dry electrode and a manufacturing method thereof, belonging to the field of bioelectrodes, and the method comprises the following steps: preparing a fiber membrane by electrostatic spinning; preparing a hydrogel film containing conductive filler on the fiber film to obtain a mixed film; puncturing the mixed film to distribute air holes on the mixed film; manufacturing a wavy conductor by using a mixed solution mixed with a prepolymer, a cross-linking agent and a conductor material; transferring the wave-shaped conductor to the surface of the hydrogel film; and baking the mixed film to obtain the high-conductivity breathable hydrogel dry electrode. The mixed film and the wavy conductor can be prepared independently respectively, so that the conductor is prevented from being solidified on the hydrogel, the prepared electrode has good air permeability, the prepared electrode is easy to strain and attach to the skin when stressed, the wavy conductor with the elasticity of the polymer can bear large-amplitude deformation, and the surface of the wavy conductor exposed on the dry electrode is directly contacted with the skin, so that the dry electrode has lower contact impedance.

Description

High-conductivity breathable hydrogel dry electrode and manufacturing method thereof

Technical Field

The invention relates to a high-conductivity breathable hydrogel dry electrode and a manufacturing method thereof, belonging to the field of bioelectrode.

Background

Recent advances in nanostructured materials and non-traditional device design have transformed various devices in bioelectronics from rigid and bulky forms to flexible and ultra-thin forms, and have brought tremendous benefits to bioelectronics. For example, soft bioelectronic devices have the ability to mechanically deform, conform to soft, curved organs (e.g., brain, heart, and skin), reduce long-term side effects in vivo, and enable researchers to measure high quality biological signals to provide real-time feedback therapy. In addition, the retractable electronic device is widely applied to the epidermis, wearable devices, soft robots, and implants, and can be well attached to a curved surface such as cloth, an organ, or the skin.

Most stretchable devices comprise two parts, an active (conductive) layer and a substrate. The active layer includes a conductor and a hydrogel for protecting or supporting the conductor. The stretchable dry electrodes of the prior art have the following disadvantages.

1. The substrate base material is mainly composed of silicone rubber, polyethylene naphthalate, a polyurethane polymer, or a fluorinated rubber, and its modulus ranges from several hundred kilopascals or megapascals. Therefore, the conventional hydrogel electrode has higher elastic modulus and a deformation amplitude which cannot be well attached to the cambered surface of an organ, so that the wearing comfort is poor.

2. Carbon-based materials using hydrogel or printing methods have been attempted to incorporate organic-based stretchable conductors. However, the conductivity of metal is still better than that of current organic conductors, but metal conductors are less elastic than organic conductors and are easily broken in tension.

3. The signal acquisition electrode of the telescopic electronic equipment, particularly the flexible bioelectronic device, is generally air-tight and waterproof, the air permeability of the film with a compact structure is poor, sweat is easy to accumulate, the influence of the sweat is easy to be received in the motion process, the comfort level is influenced, the increase of the contact impedance of the electrode and the skin is also caused, the signal acquisition quality is reduced, and the long-term use is not facilitated.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the high-conductivity breathable hydrogel dry electrode and the manufacturing method thereof, and the high-conductivity breathable hydrogel dry electrode is stronger in adhesion and lower in contact impedance.

The technical scheme adopted by the invention for solving the technical problem is as follows:

in a first aspect, the present application provides a method for manufacturing a highly conductive gas permeable hydrogel dry electrode, comprising the steps of:

preparing a fiber membrane by electrostatic spinning;

preparing a hydrogel film containing conductive filler on the fiber film to obtain a mixed film;

puncturing the mixed film to ensure that air holes are distributed on the mixed film;

manufacturing a wavy conductor by using a mixed solution mixed with a prepolymer, a cross-linking agent and a conductor material;

transferring the wavy conductor to the surface of the hydrogel film;

and baking the mixed film to obtain the high-conductivity breathable hydrogel dry electrode.

The dry electrode prepared by the manufacturing method of the high-conductivity breathable hydrogel dry electrode provided by the application has strong breathability, keeps higher toughness on the premise of being easy to adhere to a cambered surface physiological structure, and has lower impedance when being in direct contact with skin by a wavy conductor.

Further, the conductor material is selected from one or more of silver nanowires, silver nanosheets, silver-gold nanowires, carbon fibers and graphene.

Metal nanomaterials have extraordinary electrical and thermal conductivity, and are flexible and light, although the bulk state of the metal is hard and heavy, which is incompatible with soft bioelectronics. Thus, when they are mixed with an elastic medium, they can form a flexible and electrically conductive nanocomposite. Such nanostructured metal-based materials can be classified by their size, such as 0-dimensional, 1-dimensional, and 2-dimensional nanomaterials, including nanoparticles, nanowires, and nanoplatelets, respectively. The percolation threshold of the 0-dimensional nanomaterial is higher than that of the 1-dimensional or 2-dimensional nanomaterial. 1-dimensional or 2-dimensional nanomaterials have been widely used for conductive nanocomposites, and 0-dimensional nanomaterials can enhance the contact quality in the percolating network of 1-dimensional or 2-dimensional nanomaterials.

Further, the step of manufacturing the wavy conductor by using the mixed solution mixed with the prepolymer, the cross-linking agent and the conductor material comprises the following steps:

printing the mixed solution on teflon;

sintering the mixed solution into a conductor film;

cutting the conductor film to obtain a wavy conductor;

the step of transferring the wavy conductor to the surface of the hydrogel film comprises:

transferring the wavy conductor from the Teflon to the surface of the hydrogel film by using a water-soluble adhesive tape, and then dissolving the water-soluble adhesive tape.

In the prior art, a conductor is usually directly arranged on a substrate, the conductor is protected by hydrogel, although the hydrogel contains conductive filler, the conductivity of the conductor is stronger than that of the hydrogel containing the conductive filler, the conductor is directly exposed in the application, and the conductor can be directly contacted with the skin, so that the prepared electrode has lower resistance. The technical difficulty is how to ensure the quality of the conductor after the conductor is exposed. The technical difficulty is solved by the following aspects in the scheme.

First, the conductor is not a pure metal conductor, but is made by mixing a prepolymer, a cross-linking agent and a conductor material, and the elasticity of the polymer is utilized to enable the conductor to be elastically restored after being greatly deformed.

Secondly, the conductor is not simply linear or tree-shaped branch, but is cut into wave shape, which is helpful for releasing stress, preferably, the wave shape and the wave shape are mutually staggered, so that the conductor is not easy to damage when being deformed along with the substrate.

Thirdly, the shielding layer with the opposite pattern is used as a mask to directly print the complex shape in the prior art, and then the complex shape is sintered, so that small branches in the complex shape are heated in a large area and are easy to crack due to water loss when being sintered, the tensile property is poor, but the conductor in the prior art is covered by hydrogel, the hydrogel can be filled into cracks, and the conductor is also protected by the hydrogel all the time in the using process, so that the problem is not solved. The conductor is exposed, only one side of the conductor is protected by the hydrogel film, and the conductor film is sintered into a sheet and then cut during the manufacturing process, so that the conductor film is not easy to crack after being sintered into a sheet.

Fourthly, sintering is carried out firstly, and then transferring is carried out, so that the hydrogel is prevented from being dehydrated due to the fact that conductors are solidified on the hydrogel.

Further, the prepolymer is a prepolymer of Ecoflex, and the step of sintering the mixed solution into a conductor film includes:

a first stage of heat-treating the mixed solution on Teflon at 60 ℃ for 1 hour;

in the second stage, the temperature is raised to 110 ℃, and the temperature is kept for 2 hours;

in the third stage, the temperature is raised to 130 ℃ and kept constant for 2 hours.

In the scheme, three-stage sintering is adopted, and the solvent is slowly evaporated, so that the conductor film is less prone to deformation and cracking.

Further, the electrostatic spinning raw material of the fiber membrane is one of the following combinations: a combination of PVB (polyvinyl butyral) and Ecoflex (a copolyester manufactured by BASF, germany), a combination of PVB and PVDF (polyvinylidene fluoride), a combination of PVB and PDMS (polydimethylsiloxane), a combination of PVB and silicone rubber.

The combination of PVB and Ecoflex is the optimal choice, and Ecoflex prepolymer is widely applied to the biomedical field, and has excellent chemical inertness, biocompatibility and mechanical properties. However, electrostatic spinning film formation requires overlapping and mutually bonding of filaments to form a film, ecoflex has insufficient viscosity and poor film formation quality when used for electrostatic spinning, and due to the proper addition of PVB, the viscosity is better in the electrostatic spinning process, and the spinning effect is better. Moreover, PVB has excellent biocompatibility, good adhesion to organ surfaces, good solubility in ethanol, and poor water solubility. Although polymers such as PDMS and PEDOT show hydrophobicity, the hydrophobicity is not good (the contact angle is 120-130 degrees), the water is easy to absorb, the testing under the motion state is not facilitated, and particularly, the film after electrostatic spinning has the risk of water accumulation. EcoFlex has very good hydrophobicity and is very tough, withstanding strains of up to 900%. This material also showed high stability (-53 to 232 ℃) over a wide operating temperature range. EcoFlex itself can retain its original dimensions after multiple stretching cycles. Thus, films prepared using EcoFlex/PVB electrospinning have higher toughness and stability, providing excellent reusability.

Further, the fiber membrane is prepared from electrostatic spinning raw materials of a combination of PVB and Ecoflex, wherein the Ecoflex accounts for 60-80% by mass, and the balance is PVB, and the fiber membrane is prepared by electrostatic spinning, wherein the step of preparing the fiber membrane comprises the following steps:

adding PVB and Ecoflex into a DMF solvent, and sealing and stirring for 6 hours to prepare an electrostatic spinning solution with the mass concentration of 28%;

adding the electrostatic spinning solution into an injector of spinning equipment, wherein the process parameters are that the flow rate is 1ml/h, the environmental temperature is 25 +/-2 ℃, and the environmental relative humidity is 45 +/-5%;

drying to obtain the fiber membrane with the thickness of 0.5mm-2mm.

The fiber membrane prepared by electrostatic spinning has the characteristics of small pore diameter and high porosity, and has excellent flexibility.

The application punctures on the mixed membrane, both can strengthen the air permeability of dry electrode, has also weakened the mutual restraint between the substrate material to a certain extent in other words, has weakened the mutual restraint between the hydrogel material, makes dry electrode take place the strain more easily when the atress, more easily with skin laminating. Based on the same principle, fibrous films with high porosity are also breathable and conform more readily to the skin than sheets of substrates that are hot-coated to form a film.

Preferably, the aperture of the air holes is 0.1mm-0.5mm, and 30-50 air holes per square centimeter, so that the mixed membrane has enough toughness and adhesion force on the premise of being easily attached to the skin and being breathable.

Further, the step of preparing the hydrogel film containing the conductive filler on the fiber film to obtain the mixed film comprises the following steps:

according to the formula of PDMS: a crosslinking agent: conductive filler =10:1:1-15, preparing a hydrogel pre-solution under negative pressure;

and coating the hydrogel pre-solution on the fiber membrane, curing for 5 minutes in an environment of ultraviolet rays and ozone, and placing in a humidity box for one day to obtain the mixed membrane.

Further, the conductive filler is selected from one or more of carbon powder, silver nanowires, graphene, silver nanosheets, PEDOT PSS and carbon nanotubes.

Further, the mixing ratio of the conductor material, the prepolymer and the crosslinking agent by mass is 1:0.20-1.2:0.18-1.

Further, before the step of preparing the hydrogel film containing the conductive filler on the fiber film, the method further comprises the following steps:

and immersing the fiber membrane into 2wt% of benzophenone ethanol solution to perform surface treatment on the fiber membrane.

The surface treatment can improve the wettability and the adhesiveness of the surface of the fiber membrane, so that the subsequent fiber membrane can be better attached to hydrogel.

In a second aspect, the present application provides a highly conductive gas permeable hydrogel dry electrode made by the method of the first aspect. The dry electrode has low contact resistance, easy strain generation under stress and strong air permeability.

The beneficial effects of the invention are: the substrate of the dry electrode is manufactured by adopting electrostatic spinning, the hydrogel is punctured, the dry electrode has good air permeability, the dry electrode is easy to generate strain when stressed and is easy to be attached to the skin, the wavy conductor with the elasticity of the polymer can bear large-amplitude deformation, the wavy conductor is exposed on the surface of the dry electrode and is directly contacted with the skin, the dry electrode has lower contact impedance, the mixed film and the wavy conductor can be respectively and independently manufactured, the conductor is prevented from being solidified on the hydrogel, and the manufactured dry electrode has low contact impedance, is easy to generate strain when stressed and has strong air permeability.

Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the application. The objectives and other advantages of the application may be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

Fig. 1 is a flowchart of a method for manufacturing a highly conductive gas-permeable hydrogel dry electrode according to an embodiment of the present application.

Fig. 2 is a schematic structural diagram of a highly conductive gas-permeable hydrogel dry electrode provided in an embodiment of the present application.

Reference numerals are as follows: 1. a fibrous membrane; 2. a hydrogel film; 21. mixing the films; 3. a wave-shaped conductor; 32. cutting excess materials of the conductor film; 4. air holes are formed; 8. a water-soluble adhesive tape; 9. teflon tape.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Aiming at the problems of poor air permeability, high contact resistance and low adhesion of a flexible hydrogel electrode in the prior art, the invention provides a manufacturing method of a high-conductivity air-permeable hydrogel dry electrode, which comprises the following steps of:

s1: and (3) preparing a fiber membrane by electrostatic spinning.

S2: and manufacturing a hydrogel film containing conductive filler on the fiber film to obtain the mixed film.

S3: and puncturing the mixed film to ensure that the mixed film is distributed with air holes.

S4: a wave-shaped conductor is manufactured by using a mixed liquid mixed with a prepolymer, a cross-linking agent and a conductor material.

S5: and transferring the wavy conductor to the surface of the hydrogel film.

S6: and baking the mixed film to obtain the high-conductivity breathable hydrogel dry electrode.

Wherein, the electrostatic spinning raw material in the step S1 is one of the following combinations: a combination of PVB and Ecoflex, a combination of PVB and PVDF, a combination of PVB and PDMS, a combination of PVB and silicone rubber. The conductive filler is selected from one or more of carbon powder, silver nanowires, graphene, silver nanosheets, PEDOT PSS and carbon nanotubes. The conductor material is selected from one or more of silver nanowires, silver nanosheets, silver-gold nanowires, carbon fibers and graphene. Through reasonable analysis of the steps, the step S4 can be parallel to the step S1-S2-S3, and the wavy conductor is attached to the mixed film and pressed together in the step S5, so that the lower layer and the upper layer are not required to be manufactured, and the production efficiency is improved.

Specifically, step S1 specifically operates as follows: PVB and Ecoflex are added into a DMF (dimethyl formamide) solvent, the mass ratio of the Ecoflex prepolymer in the PVB and Ecoflex mixture ratio is 60-80%, a solution with the mass concentration (the percentage of the PVB and the Ecoflex to the total mass of the solution) of 28% is prepared, the bottle mouth is sealed by a sealing cloth, and the solution is placed on a stirrer to be stirred for 6 hours. And then adding the solution into an injector arranged in DXES-N spinning equipment, setting the flow rate of 1ml/h, 25KV direct current voltage, setting the distance between a spray head and a collector to be 20cm, setting the environmental temperature to be 25 +/-2 ℃ and the environmental relative humidity to be 45 +/-5%, carrying out electrostatic spinning under the conditions, and drying to obtain the PVB/Ecoflex fiber membrane with the thickness of about 0.5mm-2mm.

Step S2 also comprises the following steps: and immersing the fiber membrane into 2wt% of benzophenone ethanol solution to carry out surface treatment on the fiber membrane. The surface treatment can improve the wettability and the adhesiveness of the surface of the fiber membrane, so that the subsequent fiber membrane can be better attached to hydrogel.

The specific operation of step S2 is as follows: the hydrogel was weighed according to the hydrogel pre-solution formulation (PDMS: crosslinker: conductive filler =10: 1-15), placed in a beaker and stirred clockwise with a glass rod for 10 minutes, then placed in a vacuum machine to evacuate air for about 15 minutes, removing air bubbles from the solution. The hydrogel pre-solution was poured onto the fiber membrane and spread evenly, then cured with uv and ozone for 5 minutes and placed in a humidity chamber for 1 day.

In step S3, a sharp needle or a laser drilling technology can be used for puncturing the hydrogel film, so that the hydrogel film has a ventilation function, and the aperture of the ventilation hole is about 0.1mm-0.5mm.

The specific operation of step S4 is as follows: the prepolymer of Ecoflex and the crosslinking agent were mixed at a mass ratio of 1. Subsequently, a conductive material was added to the premixed solution, and the mixture was stirred for 30 minutes to obtain a mixed solution. Then printed on teflon and the film was subjected to three-stage annealing sintering, the first stage corresponding to a gentle heat treatment at 60 ℃ for 1 hour to slowly evaporate the solvent and cure Ecoflex, and then the curing temperature was raised to 110 ℃ for 2 hours and then to 130 ℃ for 2 hours to sinter the conductor material. The sintered elastic conductor (conductor film) is cut into a wave shape by a laser cutting technique, which helps to relieve strain.

The Ecoflex has very high toughness, can play a supporting and protecting role when being combined with a conductor material, and particularly the conductive and stability of the electrode can be improved by using the Ecoflex as an easily-broken material such as silver nanowires and silver nanosheets.

Step S5 may conformally attach the printed silver ink (the conductive filler of the mixed liquid is selected from silver nanowires and silver nanosheets, and is therefore referred to as silver ink) to the mixed film using a transfer method of a water-soluble 3M adhesive tape.

Typically, screen-printing inks are sintered by thermal annealing or intense pulsed light. However, both of these methods result in drying of the mixed film, reducing its stretchability, since it is made of an aqueous hydrogel. Conversely, if the adhesion of the tape to the conductor film is stronger than the adhesion of the ink to the original substrate, the printed silver ink can be conformally adhered to the hybrid substrate using a transfer method of a water-soluble 3M tape, for example, using a chemically stable and non-adhesive teflon tape as the original substrate.

In the embodiment represented in fig. 1, the mixed solution is printed on a teflon tape 9, after three-stage sintering, the wave-shaped conductor 3 is cut out by laser, the conductor film cutting excess 32 is torn off, the wave-shaped conductor 3 is stuck up from the teflon tape 9 by a water-soluble tape 8, and the water-soluble tape is pressed on the mixed film 21 again. The deionized water was dropped onto the film surface to dissolve the tape quickly (within a few minutes).

And S6, baking the electrode in an oven at the temperature of 80 ℃ for 1 hour, evaporating deionized water for dissolving the water-soluble adhesive tape, and combining the wavy conductor with the mixed film to obtain the high-conductivity breathable hydrogel dry electrode.

In the embodiment of the application, the Ecoflex copolyester has ultrahigh toughness, low weight, heat resistance and corrosion resistance. PVB is used as matrix material, which has excellent biocompatibility and good adhesion to the surface. The hydrogel film adopts a structure of fusing PDMS and conductive filler, and has flexibility and high conductivity. The conductor material adopts a structure that nano metal is matched with flexible organic matters, the wave shape is favorable for releasing strain, and the nano microstructure is attached to the gap on the surface of the skin, so that the contact area can be increased, and the impedance can be reduced.

Referring to fig. 2, the dry electrode manufactured according to the embodiment of the present application includes a fiber film 1, a hydrogel film 2 attached to the fiber film 1, and a wave-shaped conductor 3 attached to the hydrogel film 2, wherein the wave-shaped conductor 3 includes a plurality of staggered wave lines, the fiber film 1 and the hydrogel film 2 form a mixed film, and the mixed film is provided with air holes 4. The dry electrode has the comfort, ultrahigh toughness, excellent air permeability and high conductivity of a flexible electrode, and can resist the influence of motion artifacts.

Example 1

PVB and Ecoflex are added into a DMF solvent, in the ratio of PVB to Ecoflex, the mass of Ecoflex prepolymer accounts for 80%, a solution with the mass concentration of 28% is prepared, the bottle mouth is sealed by a sealing cloth, and the mixture is placed on a stirrer to be stirred for 6 hours. And then adding the solution into an injector arranged in DXES-N spinning equipment, carrying out electrostatic spinning at the flow rate of 1ml/h and the direct current voltage of 25KV under the conditions that a spray head is 20cm away from a collector, the temperature is 25 +/-2 ℃, and the relative humidity is 45 +/-5%, and drying to obtain the PVB/Ecoflex fiber membrane with the thickness of 2mm.

The PVB/Ecoflex fiber membrane is cut into a rectangular shape with a proper size, and is immersed in a 2wt% benzophenone ethanol solution to carry out surface treatment on the fiber membrane. The hydrogel pre-solution is prepared by the following steps of weighing PDMS, a crosslinking agent, carbon powder =10 and 15, placing the mixture into a beaker, stirring the mixture clockwise for 10 minutes by using a glass rod, and then placing the beaker into a vacuum machine to pump air for about 15 minutes to remove bubbles in the solution. The hydrogel pre-solution was poured onto the rectangular fiber membrane and spread evenly, then cured with uv and ozone for 5 minutes and placed in a humidity chamber for 1 day. After the mixed membrane is solidified, puncture operation is carried out on the hydrogel film by using a laser drilling technology, and the aperture of the air holes is 0.1mm.

The prepolymer of Ecoflex and the crosslinking agent were mixed for 5 minutes at a mass ratio of 1. Subsequently, the conductive material was added to the premixed solution, and the mixture was stirred for 30 minutes. The mixing mass ratio of the silver nanosheets, the Ecoflex and the methyl isobutyl ketone is 7.2:1.6:1.5. then printed on teflon and the film was annealed in three stages, the first stage corresponding to a 1 hour mild heat treatment at 60 ℃ to slowly evaporate the solvent and cure Ecoflex, and then the curing temperature was raised to 110 ℃ for 2 hours and then to 130 ℃ for 2 hours to sinter the conductor material. And cutting the sintered elastic conductor into a wave shape by using a laser cutting technology. Finally, it was separated from the teflon substrate using a water-soluble tape.

Pressing the separated wave-shaped conductor onto the mixed film in a shape-preserving manner, dripping deionized water onto the surface of the film so as to quickly dissolve the adhesive tape, and then placing the film in an oven to bake for 1 hour at 80 ℃ to obtain the dry electrode.

Example 2

PVB and Ecoflex are added into a DMF solvent, in the ratio of PVB to Ecoflex, the mass of Ecoflex prepolymer accounts for 60%, a solution with the mass concentration of 28% is prepared, the bottle mouth is sealed by a sealing cloth, and the mixture is placed on a stirrer to be stirred for 6 hours. And then adding the solution into an injector arranged in DXES-N spinning equipment, carrying out electrostatic spinning at the flow rate of 1ml/h, the direct-current voltage of 25KV, the distance between a spray head and a collector of 20cm, the temperature of 25 +/-2 ℃ and the relative humidity of 45 +/-5%, and drying to obtain the PVB/Ecoflex fiber membrane with the thickness of 1mm.

The PVB/Ecoflex fiber membrane is cut into a rectangular shape with a proper size, and is immersed in a 2wt% benzophenone ethanol solution to carry out surface treatment on the fiber membrane. Weighing a hydrogel pre-solution according to the proportion of PDMS to a crosslinking agent CNT (carbon nano tube) = 10. The hydrogel pre-solution was poured onto the above rectangular film and spread evenly, then cured with uv and ozone for 5 minutes and placed in a humidity chamber for 1 day. After the mixed membrane is solidified, a sharp needle is used for puncturing the hydrogel film, so that the hydrogel film has a ventilation function, and the aperture of the ventilation hole is 0.5mm.

The prepolymer of Ecoflex and the crosslinking agent were mixed for 5 minutes at a mass ratio of 1. Subsequently, the conductive material was added to the premixed solution, and the mixture was stirred for 30 minutes. The mixing mass ratio of the silver nanosheet/silver nanowire, the Ecoflex and the methyl isobutyl ketone is 7:1.5:1.3, in the silver nano sheet/silver nanowire, the mixing mass ratio of the silver nano sheet to the silver nanowire is 9. Then printed on teflon and the film was annealed in three stages, the first stage corresponding to a 1 hour mild heat treatment at 60 ℃ to slowly evaporate the solvent and cure Ecoflex, and then the curing temperature was raised to 110 ℃ for 2 hours and then to 130 ℃ for 2 hours to sinter the conductor material. And cutting the sintered elastic conductor into a wave shape by using a laser cutting technology. Finally, it was separated from the teflon substrate using a water-soluble tape.

Pressing the separated elastic conductor onto the mixed film conformally, dripping deionized water onto the surface of the film to dissolve the adhesive tape quickly, and baking in an oven at 80 ℃ for 1 hour to obtain the ultrahigh-toughness high-conductivity breathable hydrogel dry electrode.

Example 3

PVB and Ecoflex are added into a DMF solvent, in the ratio of PVB to Ecoflex, the mass of Ecoflex prepolymer accounts for 70 percent, a solution with the mass concentration of 28 percent is prepared, the bottle mouth is sealed by a sealing cloth, and the mixture is placed on a stirrer to be stirred for 6 hours. And then adding the solution into an injector arranged in DXES-N spinning equipment, carrying out electrostatic spinning at the flow rate of 1ml/h, the direct-current voltage of 25KV, the distance between a spray head and a collector of 20cm, the temperature of 25 +/-2 ℃ and the relative humidity of 45 +/-5%, and drying to obtain the PVB/Ecoflex fiber membrane with the thickness of 1mm.

The PVB/Ecoflex fiber membrane was cut into a rectangular shape of an appropriate size, and immersed in a 2wt% benzophenone ethanol solution to perform surface treatment on the PVB/Ecoflex fiber membrane. The hydrogel pre-solution is weighed according to the proportion of PDMS to the cross-linking agent PEDOT to PSS = 10. The hydrogel pre-solution was poured onto the above rectangular film and smeared evenly, then cured with uv and ozone for 5 minutes and placed in a humidity chamber for 1 day. After the mixed membrane is solidified, puncture operation is carried out on the hydrogel film by using a laser punching technology, so that the hydrogel film has a ventilation function, and the aperture of the ventilation hole is 0.3mm.

The prepolymer of Ecoflex and the crosslinking agent were mixed for 5 minutes at a mass ratio of 1. Subsequently, the conductive material was added to the premixed solution, and the mixture was stirred for 30 minutes. The mixing mass ratio of the silver-gold nanowires to the graphene to the Ecoflex to the methyl isobutyl ketone is 1:1.2:1. in the silver-gold nanowires/graphene, the mixing mass ratio of the silver-gold nanowires to the graphene is 10. Then printed on teflon and the film was annealed in three stages, the first stage corresponding to a gentle heat treatment at 60 ℃ for 1 hour to slowly evaporate the solvent and cure Ecoflex, and then the curing temperature was raised to 110 ℃ for 2 hours and then to 130 ℃ for 2 hours to sinter the conductor material. And cutting the sintered elastic conductor into a wave shape by using a laser cutting technology. Finally, it was separated from the teflon substrate using a water-soluble tape.

According to the embodiment of the application, the PVB/Ecoflex fiber membrane is prepared through electrostatic spinning, then the breathable conductive hydrogel is coated on the PVB/Ecoflex fiber membrane, and the PVB/Ecoflex fiber membrane, the breathable conductive hydrogel and the elastic conductor structure are combined with the wavy elastic conductor to prepare the dry electrode. Compared with the traditional hydrogel dry electrode, the electrode has the advantages of no need of conductive gel and high skin affinity, better comfort, ultrahigh toughness, excellent air permeability and high conductivity. Printable and highly stretchable conductors are made by transferring the printed mixed liquor onto a hydrogel film using water-soluble tape, which is simpler than other techniques using elastomeric stamps or sacrificial layers. The elastic conductor is of an Ecoflex prepolymer and conductor material structure, the conductor material is a nanoscale high-conductivity conductor, and the nanostructure can fill air gaps on the surface of the skin, so that the elastic conductor can be well attached to the surface of the skin, and the influence of motion artifacts is reduced. The addition of the Ecoflex prepolymer results in a conductive material with high toughness and can be highly stretched without deformation cracking. The wavy appearance design is favorable for releasing stress, and the toughness of the elastic conductor is further improved.

In the description of the present specification, reference to the description of the terms "one embodiment," "certain embodiments," "illustrative embodiments," "example," "specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims

1. A method for manufacturing a high-conductivity breathable hydrogel dry electrode is characterized by comprising the following steps:

preparing a fiber membrane by electrostatic spinning;

transferring the wavy conductor to the surface of the hydrogel film;

2. The method of claim 1, wherein the step of forming the wave-shaped conductor from a mixture of the prepolymer, the crosslinking agent and the conductor material comprises:

printing the mixed solution on teflon;

sintering the mixed solution into a conductor film;

cutting the conductor film to obtain a wavy conductor;

3. The method of claim 2, wherein the prepolymer is Ecoflex prepolymer and the step of sintering the mixture into a conductive film comprises:

4. The method for manufacturing the high-conductivity breathable hydrogel dry electrode according to claim 1, wherein the raw material for the electrostatic spinning of the fiber membrane is one of the following combinations: a combination of PVB and Ecoflex, a combination of PVB and PVDF, a combination of PVB and PDMS, a combination of PVB and silicone rubber.

5. The method of claim 4, wherein the electrospinning raw material of the fibrous membrane is a combination of PVB and Ecoflex, wherein Ecoflex accounts for 60-80% by mass, and the balance is PVB, and the step of electrospinning to prepare the fibrous membrane comprises:

adding PVB and Ecoflex into a DMF solvent, sealing and stirring for 6 hours to prepare an electrostatic spinning solution with the mass concentration of 28 percent;

adding the electrostatic spinning solution into an injector of spinning equipment, wherein the process parameters are that the flow rate is 1ml/h, the ambient temperature is 25 +/-2 ℃, and the ambient relative humidity is 45 +/-5%;

drying to obtain the fiber membrane with the thickness of 0.5mm-2mm.

6. The method for manufacturing the highly conductive and breathable hydrogel dry electrode according to claim 1, wherein the step of forming the hydrogel film containing the conductive filler on the fiber film to obtain the mixed film comprises:

7. The method for manufacturing the highly conductive and breathable hydrogel dry electrode according to claim 1, wherein the step of forming the hydrogel film containing conductive filler on the fiber film further comprises the steps of:

and immersing the fiber membrane into 2wt% of benzophenone ethanol solution to carry out surface treatment on the fiber membrane.

8. The method for manufacturing the high-conductivity breathable hydrogel dry electrode according to claim 1, wherein the conductive filler is selected from one or more of carbon powder, silver nanowires, graphene, silver nanosheets, PEDOT PSS and carbon nanotubes.

9. The method for manufacturing the high-conductivity breathable hydrogel dry electrode according to claim 1, wherein the conductor material is selected from one or more of silver nanowires, silver nanosheets, silver-gold nanowires, carbon fibers and graphene.

10. A highly conductive, gas permeable, hydrogel dry electrode made by the method of any one of claims 1 to 9.