WO2021197462A1 - Elastic conductor composite film and preparation method therefor - Google Patents

Abstract

Disclosed are an elastic conductor composite film and a preparation method therefor. An electrospinnable thermoplastic elastomer and a liquid metal are used as raw materials for the elastic conductor composite film, a base film layer of the composite film is obtained by means of a electrospinning technique, a surface of the base film layer is coated with the liquid metal, and the resulting composite film has a good stretchability and a high conductivity and has excellent electrical stability and stretching resistance; and electrospinning fibers of the base film layer are of a net-shaped pore structure, such that the composite film also has a good steam permeability and air permeability. The thermoplastic elastomer and the liquid metal for preparing the composite film are both low-cost materials, such that the production cost of the composite film is reduced, and the economic applicability is good; and general preparation means such as electrospinning and coating are conductive to large-scale industrial production, the composite film may be physically expanded according to actual application requirements, and compared existing conductive materials, the elastic conductor composite film in the present invention is more suitable for multiple fields, such as stretchable electronic circuits, flexible batteries, stretchable light source devices and wearable apparatuses.

Description

Elastic conductor composite film and preparation method thereof

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office on April 3, 2020, the application number is 202010257987.0, and the invention title is "an elastic conductor composite film and its preparation method", the entire content of which is incorporated by reference In this application.

Technical field

The invention belongs to the field of conductor materials, and specifically relates to an elastic conductor composite film and a preparation method thereof.

Background technique

Elastic conductors are an indispensable part of wearable electronic products, especially flexible electronic devices such as flexible robots, bio-information-driven devices, and medical implants for health monitoring. In addition to considering its conductivity and elasticity, the performance of elastic conductors is also an extremely important consideration. Many practical applications such as stretchable electronic circuits, flexible batteries, stretchable light source devices, etc. require conductive materials to have high electrical stability. To ensure that the device can still maintain good working performance during the deformation process, it is quite challenging for a highly stretchable elastic conductor to have high electrical stability at the same time. In addition, in addition to high electrical stability, the application of porous film elastic conductors to elastic conductors in wearable electronic products is also urgently needed, and such conductive materials are also required to have good air and vapor permeability properties. With the development of wearable products, future wearable electronic products also need stretchable conductive materials to meet the conditions of supporting multi-function, small package size, and high integration to support better product performance.

However, at present, there is no relatively mature and convenient method for preparing the above-mentioned elastic conductors with the advantages of good stretchability, high conductivity, and high stability.

Summary of the invention

Based on this, the present invention aims to provide an elastic conductor composite film and a preparation method thereof to overcome the above-mentioned defects in the prior art, so that it can satisfy high stretchability, high conductivity and high electrical stability at the same time, and also has both Good vapor permeability and air permeability.

An elastic conductor composite film of the present invention comprises: a base film layer and a coating material coated on the surface of the base film layer, wherein the base film layer is an electrospun thermoplastic elastomer, and the coating material is a liquid metal with a melting point lower than room temperature .

Preferably, in order to further increase the electrical conductivity of the composite film, a nano-silver conductive layer is also formed between the base film layer and the coating material.

Preferably, the elastic conductor composite film has a multilayer structure, which is formed by alternately stacking a base film layer and a coating material in a vertical manner.

Preferably, the elastic conductor composite film has a multilayer structure, which is formed by alternately stacking a base film layer, a nano silver conductive layer, and a coating material in turn.

Preferably, the coating material passes through a patterned mold to form the pattern on the surface of the base film layer.

Preferably, in order to improve the electrical contact performance of the elastic conductor composite film, a layer of ion conductive hydrogel is also covered on the surface of the composite film in contact with the biological body, and the pattern formed by the ion conductive hydrogel is coated on the covered surface. The pattern formed by the material is consistent.

Preferably, the electrospunable thermoplastic elastomer is a styrene-butadiene-styrene block copolymer, and the mass percentage concentration of the electrospunable thermoplastic elastomer in the formed electrospun polymer solution is 5 wt% -20wt%.

Preferably, the liquid metal is a room temperature liquid gallium-based alloy.

Preferably, the room temperature liquid gallium-based alloy is a eutectic gallium-indium alloy, wherein the mass ratio of the two elements of gallium-indium is 75:25.

On the other hand, the present invention also provides a method for preparing the above-mentioned elastic conductor composite film, which includes:

Step S1. Dissolve the electrospun thermoplastic elastomer in the intermediate agent to form an electrospun polymer solution;

Step S2. Use the electrospinning polymer solution for electrospinning, and collect electrospinning on the steel plate to form the base film layer of the elastic conductor composite film;

Step S3. Coating a coating material on the surface of the base film layer, wherein the coating material is a liquid metal with a melting point lower than room temperature.

Preferably, before step S3, the method further includes:

A nano-silver conductive layer is formed on the surface of the base film layer. Specifically, the base film layer is sequentially immersed in a nano-silver solution, a reducing agent, and anhydrous ethanol.

Preferably, after step S3, the method further includes:

Use the polymer solution to electrospin a new base film layer on the surface where the base film layer has been coated with the coating material, coat the surface of the new base film layer with the coating material, and so on, alternate electrospinning and coating. The coating material is applied until the elastic conductor composite film with the required number of layers to form a multilayer structure is obtained.

Preferably, after step S3, the method further includes:

The polymer solution is used to electrospin a new base film layer on the surface where the base film layer has been coated with the coating material, and the nano silver conductive layer and the coating material are sequentially formed on the surface of the new base film layer. By analogy, electrospinning, nano-silver conductive layer formation and coating material coating are alternately performed until the required number of layers is obtained to form a multilayer structured elastic conductor composite film.

Preferably, forming a nano-silver conductive layer on the surface of the base film layer includes:

Soak the base film layer in the nano silver solution for 5 minutes, take out the base film layer and place it in the air to dry naturally at room temperature. The air-dried base film layer is soaked in the reducing agent for no less than 5 minutes. Soak in water and ethanol for no less than 10 minutes, take the base film layer soaked in absolute ethanol and place it in the air at room temperature to dry naturally, so that a nano-silver conductive layer is formed on the surface of the base film layer.

Preferably, the nano-silver solution is prepared by dissolving silver trifluoroacetate in ethanol to obtain a solution with a concentration of 0.1-1 g/mL.

Preferably, the reducing agent is an ethanol solution of hydrazine hydrate.

Preferably, coating the coating material on the surface of the base film layer includes:

A mold with a pattern is placed on the surface of the base film layer so that the coating material forms the pattern when the surface of the base film layer is coated.

Preferably, the preparation of the elastic conductor composite film further includes:

A layer of ion conductive hydrogel is covered on the side of the composite membrane to be in contact with the biological body, and the pattern formed by the ion conductive hydrogel is consistent with the pattern formed by the coating material on the covered surface.

Preferably, the intermediate agent is dichloroethane.

Preferably, dissolving the electrospunable thermoplastic elastomer in the intermediate agent to form the electrospinning polymer solution includes:

Dissolve the styrene-butadiene-styrene block copolymer in dichloroethane to obtain an electrospinning polymer solution. The mass percentage concentration of the thermoplastic elastomer in the formed electrospinning polymer solution is 5wt%-20wt% .

Preferably, the liquid metal is a room temperature liquid gallium-based alloy.

Preferably, the room temperature liquid gallium-based alloy is a eutectic gallium-indium alloy, wherein the mass ratio of gallium and indium is 75:25.

Preferably, the thickness of the base film layer is positively related to the collection time for collecting electrospinning on the steel plate.

It can be seen from the above technical solutions that the present invention has the following beneficial effects:

The elastic conductor composite film of the present invention has good stretchability, strong conductivity, and has excellent electrical stability while resisting stretching; the base film layer electrospun fiber obtained by electrospinning technology has a net-like pore structure, thus making the The composite film also has good vapor permeability and air permeability; the thermoplastic elastomer and liquid metal used to prepare the composite film are both low-cost materials, which reduces the production cost of the composite film and has good economic applicability; electrospinning and coating Common preparation methods such as cloth are beneficial to the multi-field application of the composite film, suitable for large-scale industrial production, and the composite film can be physically expanded according to actual application requirements. Compared with the existing conductive material, the elastic conductor composite of the present invention The film is more suitable for stretchable electronic circuits, flexible batteries, stretchable light source devices, wearable devices and other fields.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without creative work.

Figure 1 is a flow chart of the preparation of an elastic conductor composite film provided by the first embodiment of the present invention;

Fig. 2 is a scanning electron microscope (SEM) image of SBS electrospun fiber of the base film layer according to an embodiment of the present invention;

3 is a statistical schematic diagram of the diameter distribution of electrospun fibers in the base film layer according to an embodiment of the present invention;

4 is a schematic diagram of a tensile stress-strain curve of a base film layer according to an embodiment of the present invention;

5a and 5b are scanning electron microscope (SEM) images of 0.8EGaIn-SBS in a natural state in Example 1 of the present invention;

6a and 6b are scanning electron microscope (SEM) images of 0.8EGaIn-SBS in a stretched state in Example 1 of the present invention;

Fig. 7 is a schematic diagram of the resistance-tensile strain curve of 0.8EGaIn-SBS in the first embodiment of the present invention;

8 is a schematic diagram of the resistance growth rate-stretching times curve of 0.8EGaIn-SBS under different tensile strains in the first embodiment of the present invention;

9 is a schematic diagram of the resistance growth rate-tensile strain curve of the composite film with different EGaIn unit area loadings according to the first embodiment of the present invention;

FIG. 10 is a schematic diagram showing the variation of conductivity and quality factor with EGaIn per unit area load in the first embodiment of the present invention;

11a to 11e are scanning electron microscope (SEM) images of composite films with different EGaIn loadings per unit area in Example 1 of the present invention;

12 is a flow chart of the preparation of the elastic conductor composite film provided by the second embodiment of the present invention;

Figure 13 is a scanning electron microscope (SEM) image of EGaIn-AgNPs-SBS according to the second embodiment of the present invention;

14 is a schematic diagram of a curve diagram of resistance growth rate and quality factor as a function of tensile strain in the second embodiment of the present invention;

15 is a schematic diagram of the resistance growth rate-stretching times curve when the tensile strain is 0% and 60% in the second embodiment of the present invention;

16 is a flow chart of the preparation of the three-layer structure elastic conductor composite film provided by the third embodiment of the present invention;

FIG. 17 is a schematic diagram of the structure of a three-layer structure elastic conductor composite membrane provided by Embodiment 3 of the present invention;

18 is a schematic diagram of the temperature change curve of the top composite film under different voltages in the third embodiment of the present invention;

19 is a schematic diagram of the highest temperature change of the top layer composite film of the third embodiment of the present invention when a step voltage is applied;

20 is a schematic diagram of the temperature-tensile strain curve of the top composite film of the third embodiment of the present invention when the applied voltage is 0.15V;

21 is a schematic diagram of the temperature change of the heating and cooling electrical stability of the top composite film of the third embodiment of the present invention when the applied voltage is 0.2V;

22 is a schematic diagram of the capacitance-PBS volume curve of the intermediate layer composite film under different tensile strains in the third embodiment of the present invention;

FIG. 23 is a schematic diagram of capacitance-NaCl concentration curves of the intermediate layer composite film of the third embodiment of the present invention under different tensile strains;

24 is a schematic diagram of the ECG signal acquisition waveforms of three wavebands in the natural state of the bottom layer composite membrane of the third embodiment of the present invention;

FIG. 25 is a schematic diagram of ECG signal acquisition waveforms in three wavebands when the bottom layer composite film of the third embodiment of the present invention is deformed.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

Example one

Referring to FIG. 1, this embodiment provides an elastic conductor composite film and a preparation method thereof. The composite film includes a base film layer and a coating material coated on the surface of the base film layer, wherein the base film layer is an electrospun thermoplastic Elastomer, the coating material is liquid metal with a melting point lower than room temperature.

It should be understood that the electrospunable thermoplastic elastomer used includes styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene block copolymer (SEBS), benzene Ethylene-isoprene-styrene block copolymer (SIS), hydrogenated styrene/isoprene block copolymer (SEPS), polyester block copolymer (TPEE), polyurethane block copolymer (TPU), polyolefin copolymer (TPO), thermoplastic vulcanized elastomer (TPV), diene block copolymer (TPB) and a series of thermoplastic elastomers that can be used for electrospinning, the present invention does not carry out this Specific restrictions.

The liquid metal used can be room temperature liquid gallium-based alloys including gallium indium alloy, gallium indium bismuth alloy, gallium indium tin alloy, etc., or a series of other liquid metals with melting points lower than room temperature can be selected, which is not specifically limited in the present invention.

In this embodiment, SBS is selected as the material of the base film layer, in which the mass ratio of styrene to butadiene is 40:60; the liquid metal coated on the surface of the base film layer is selected from the eutectic Gallium-Indium alloy in this embodiment. Indium alloy, EGaIn), where the mass ratio of gallium and indium is 75:25.

The preparation method of the composite membrane is introduced below, and the steps include:

Preparation of base film layer preparation materials, dissolve SBS in an intermediate agent to prepare a polymer solution for electrospinning, where the intermediate agent is dichloroethane, and the mass percentage concentration of SBS in the polymer solution obtained is 5wt%- 20wt%;

The electrospinning process is collected on a steel plate, and the thickness of the base film is controlled by controlling the collection time. The longer the collection time, the thicker the base film. When the preset thickness is reached, the current electrospinning process is stopped and the base film is removed from the steel plate. The layer is used to coat EGaIn afterwards;

The coating method can be one or more combinations of knife coating, brushing, Meyer bar coating, silk screen printing, and inkjet printing, but it should be understood that the coating method is not limited to the multiple described above This coating method, any coating method that can be coated with a coating material on the surface of the base film layer to form an alloy layer with no essential difference is regarded as the technical solution protected by the present invention.

In this embodiment, a knife coating method is used, and a scraper is used to form an alloy layer of EGaIn on the surface of the base film layer, and the formed elastic conductor composite film is represented by EGaIn-SBS.

By changing the loading per unit area of the alloy layer on the surface of the base film layer, the electrical properties of the composite film, such as conductivity and electrical stability, can be adjusted. Therefore, in order to express the composite film with different loading per unit area of the alloy layer, xEGaIn-SBS is used. The numerical unit of x is mg/cm ² , for example 0.8EGaIn-SBS, 1.4EGaIn-SBS, 2.0EGaIn-SBS, 2.6EGaIn-SBS, 5.0EGaIn-SBS respectively represent the unit area load of the alloy layer EGaIn on the base film layer It is 0.8mg/cm ² , 1.4mg/cm ² , 2.0mg/cm ² , 2.6mg/cm ² , 5.0mg/cm ² .

As shown in the lower part of Figure 1, on the basis of Example 1, in order to form an alloy layer with a specific pattern on the surface of the base film layer, a mold can also be used to assist in the completion of squeegee coating, specifically by placing a specific pattern on the surface of the base film layer. For the patterned mold, the alloy material is knife-coated on the mold so that the alloy layer formed on the base film layer presents the specific pattern.

The following analyzes the performance of the elastic conductor composite film provided in this embodiment from the microstructure of the composite film.

Refer to Figures 2 to 4, the SBS electrospun fibers of the base film layer are randomly stacked, and the diameter of the fibers is concentrated in the range of 500nm～5μm. Observe the tensile stress-strain curve of the base film layer as shown in Figure 4, the tensile strain can reach 1200%, with good tensile strength.

Taking 0.8EGaIn-SBS as an example, its Young's modulus is 0.11MPa, the microstructure in the natural state is shown in Figure 5a and Figure 5b, and the microstructure in the tensile state is shown in Figure 6a and Figure 6b. SBS electrospun fiber has a network-like pore structure. Figure 7 shows the curve of the resistance of 0.8EGaIn-SBS with tensile strain. When the tensile strain is 1050%, the resistance of 0.8EGaIn-SBS only increases by 2.2%. 5a to 6b, the good electrical stability of the elastic conductor composite film provided by the present embodiment during the stretching process is attributed to the deformation of the mesh pores in the electrospun fiber and the extension of the secondary gap; Fig. 8 Shows the curve of the resistance of 0.8EGaIn-SBS changing with the number of stretching times under different tensile strains. When the tensile strain is 50%, the composite film can withstand up to 20000 times of stretching without significant changes in resistance, even When the tensile strain increases to 500%, it can still withstand more than 1600 stretches while the resistance increases only by 8.9 times.

Analyze the influence of EGaIn per unit area load on the conductivity and electrical stability of the composite membrane, as shown in Figure 9 and Figure 10. In Figure 10, the curve where "■" represents the electrical conductivity, and the curve where "●" represents the quality factor. With the increase of EGaIn per unit area load, the electrical conductivity of the composite film has improved, but the electrical stability has decreased. When the unit area increment increases to 5mg/cm ² , the electrical conductivity increases to 2.0×10 ⁶ S/ m, and the quality factor representing electrical stability decreased to 0.83. The changes of the above two parameters in opposite directions can be attributed to the degradation of the SBS electrospun fiber network pore structure with the increase of EGaIn per unit area load as shown in Figure 11a As shown in FIG. 11e, compared with the stretch-resistant conductor composite film of the prior art, the elastic conductor composite film provided in this embodiment has obvious advantages in terms of conductivity and electrical stability.

Example two

Please refer to FIG. 12, in order to further improve the conductive performance of the composite film, this embodiment provides another elastic conductor composite film and a preparation method thereof. On the basis of the first embodiment, a nano-silver conductive film is formed between the base film layer and the alloy layer. Layer, so as to achieve the purpose of significantly improving the conductive performance of the composite film.

The method for preparing the base film layer and the alloy layer in this embodiment is the same as that of the first embodiment. The difference is that before coating the alloy layer, a silver nanoparticle (AgNPs) conductive layer (silver nanoparticles) needs to be formed on the base film layer. The specific steps are as follows:

Nano silver solution preparation, dissolve silver trifluoroacetate (AgTFA) in ethanol (EtOH) to obtain a solution with a concentration of 0.1-1g/mL;

The base film layer is immersed in nano-silver solution, reducing agent and absolute ethanol in turn: the electro-spinning base film layer is soaked in nano-silver solution for 5 minutes, and the base film layer is taken out and placed in the air at room temperature to dry naturally. The film layer is immersed in the reducing agent for no less than 5 minutes, so that the nano silver is reduced on the surface of the base film layer; the base film layer is taken out and soaked in absolute ethanol for no less than 10 minutes to remove the residual reducing agent; The base film layer is placed in the air at room temperature to dry naturally. At this time, a nano-silver conductive layer is formed on the surface of the base film layer. At this time, the semi-finished composite film is represented by Ag-SBS.

The reducing agent used in this example is hydrazine hydrate in ethanol.

The method of Example 1 is used to coat EGaIn on the surface of the nano-silver conductive layer to form an alloy layer, and the obtained elastic conductor composite film is represented by EGaIn-AgNPs-SBS.

The microstructure of the elastic conductor composite film with nano-silver conductive layer is shown in Figure 13. The coating of the alloy layer on the SBS base film layer with the nano-silver conductive layer did not affect the network pore structure of the electrospun fiber ; Please refer to Figure 14 and Figure 15. The curve where "■" in Figure 14 represents the resistance growth rate, the curve where "●" represents the quality factor, R _s and R on the ordinate both represent the resistance of the composite film after stretching, R _{Both s0} and R ₀ represent the resistance of the composite film in its natural state. The initial conductivity of EGaIn-AgNPs-SBS can reach 1658800S/m, and its resistance has only increased by 40.8 times when the tensile strain is 1950%. The quality factor indicating electrical stability drops to 0.48. When the tensile strain is 100%, the quality factor is still 11.9. When the tensile strain is 60%, the composite film can withstand more than 200,000 stretches and the resistance increases by only 38%. The composite membrane can still maintain good electrical stability when it is slowly deformed.

Example three

Please refer to FIG. 16, this embodiment provides a three-layer structure elastic conductor composite film and a preparation method thereof, and particularly relates to an elastic conductor composite film applied to a wearable thermotherapy device. The preparation method of the base film layer and the alloy layer is the same as in the first embodiment. The difference is that the base film layer and the alloy layer are alternately formed. The base film layer is formed first, and the alloy layer is formed later. The required specific pattern is formed on the base film layer, so it is easy to understand that each layer of elastic conductor composite film contains a base film layer and an alloy layer. The three-layer structure elastic conductor composite film is in accordance with the electrospinning sequence of the base film layer. It is represented as the top layer, the middle layer, and the bottom layer in turn. The top layer is used as a heater, the middle layer is used as a capacitive sweat sensor, and the bottom layer is used as a contact electrode for collecting biological signals of the human body. The three-layer structure elastic conductor composite film prepared in this embodiment The total thickness is 320 μm.

In order to enhance the electrical contact performance of the elastic conductor composite film in contact with the human skin, the bottom composite film used as the contact electrode is also covered with a layer of ion conductive hydrogel, the pattern of the hydrogel is consistent with the pattern of the bottom alloy layer , As shown in Figure 16, both are square-shaped and the same size and shape.

Taking into account the hydrophobicity of SBS, plasma treatment is performed on the middle layer of the composite membrane to make it hydrophilic, so that the middle layer as a sweat sensor can still pass through the surface tension of the porous fiber structure of the membrane when it is compressed. Makes sweat complete the transmission from the skin surface to the sensor. The prepared three-layer structure of the elastic conductor composite film is shown in Figure 17,

Different from the preparation of the composite film by the lamination method, the composite film obtained by the alternate preparation method of electrospinning and coating of this embodiment is an integrated composite film, which does not cause delamination during repeated use, which greatly improves the composite film In the same way, by controlling the collection time of electrospinning to control the thickness of the base film layer, the thickness of each layer can be flexibly adjusted for a composite film with a multilayer structure; simple and efficient preparation procedures are conducive to integration The design and industrial production of wearable devices with high-level and rich functions.

Combining the first three embodiments, it is easy to understand that in further embodiments, the preparation of the elastic conductor composite film of the multilayer structure can also be carried out alternately according to the preparation sequence of the base film layer, the nano-silver conductive layer, and the alloy layer. The multi-layer structure elastic conductor composite film of silver conductive layer. The preparation of this composite film will not be repeated here. Those skilled in the art can undoubtedly prepare nano-silver according to the multiple embodiments provided by the present invention. An elastic conductor composite film with a multilayer structure of conductive layers.

Performance Testing

Performance tests were performed on each layer of the three-layer structure elastic conductor composite film in the third embodiment.

For the top layer composite film used as a heater, fix it to the two ends of the stretching equipment. One end of the splint is movable and the other end is fixed. A DC step voltage of 0～0.45V is applied to the top layer of the composite film, using infrared thermal imaging. The instrument monitors the temperature change of the composite film, and each voltage is applied for at least 60s to ensure that the heating temperature of the composite film can reach a stable state. When the temperature of the composite film returns to room temperature, the infrared thermal imaging monitoring is stopped, and the composite film’s performance under different voltage applications is recorded. The temperature change curve is shown in Figure 18. It can be seen that the temperature of the composite film can be stabilized within 30s during the 6 times of voltage application; and for the heating performance of the composite film, a voltage is applied to the top composite film every 60s. The sub-voltage is increased by 0.07-0.08V, which is different from the previous application of the next voltage after the room temperature is restored. Here, the voltage is applied as soon as the temperature of the composite film reaches a stable value, and the next voltage is applied immediately. The temperature changes. When all the voltage values are applied, the infrared thermal imaging monitoring is stopped until the composite film returns to room temperature. The maximum value that the composite film can reach under different applied voltages is recorded as shown in Figure 19. It can be seen that the temperature increases with the voltage. The step change, the composite film can reach 95℃ when the last applied voltage is 0.45V, indicating that the provided elastic conductor composite film can accurately control the temperature output; for the tensile performance of the composite film, apply a DC voltage to the composite film 0.15V, stretch the composite film at a constant speed of 3mm/s, record the curve of the temperature of the composite film at this time with the tensile strain as shown in Figure 20, the temperature of the composite film increases from 34.4℃ under 0% strain to 100 At 40.1℃ under% strain, it only increased by 5.7℃, which means that when the composite film deforms with the human skin, it can still maintain good electrical stability; in addition, the electrical stability of the composite film during repeated heating and cooling is tested. , Apply a DC voltage of 0.2V to the composite membrane, and return to room temperature when the temperature of the composite membrane reaches a stable value. This is a cycle. The temperature changes of the composite membrane during 10 cycles are recorded as shown in Figure 21. The membrane can still maintain stable heating performance.

For the interlayer composite membrane used as a capacitive sweat sensor, the sweat conduction and ion permeability were tested when it was in a stretched state. Similarly, fix the intermediate layer composite film on the two splints of the stretching equipment, one end of the splint is movable, one end is fixed, and phosphate-buffered saline (PBS) is used to simulate human sweat, and different volumes of PBS are dropped. Simulate the change of the capacitance value of the composite membrane by different sweating rates on the surface of the composite membrane, and record the curve of the capacitance value of the composite membrane with the volume of PBS under different stretching degrees, as shown in Figure 22; sodium ions and chloride ions are the physiological state of the human body Therefore, the NaCl aqueous solution with different ion concentrations is used to simulate the physiological state of the human body at different stages, and the composite membrane is completely immersed in the NaCl aqueous solution to monitor the capacitance stability value of the composite membrane with the change of NaCl concentration under different stretching degrees. As shown in Figure 23, for sweat conduction and ion permeability, three tensile strains of 0%, 50%, and 100% were tested respectively. It can be seen that the sweat conduction sensitivity and ion permeability of the composite membrane vary with each other. As the degree of stretching increases.

Please refer to Figure 24 and Figure 25. For the bottom composite film used as the contact electrode for collecting biological signals, the accuracy and stability of the signal acquisition in the natural state and the deformed state are tested. A heart with a quadrupole ECG monitoring lead is used. An electric monitor, in which 3 wires are connected to the inner side of the tester’s left calf and right calf and the left wrist using ordinary ECG patches, and the other wire is connected to the right wrist using the underlying composite membrane of the present invention. When the signal is collected, the bottom layer composite film is squeezed by hand to simulate the deformation state, and the ECG signal waveforms collected in the three bands Ⅰ, Ⅱ, and Ⅲ in the natural state and the deformed state are recorded as shown in Figure 24 and Figure 25. It can be seen that the composite film can collect the required ECG signal waveform from 3 bands with a low noise ratio in both the natural state and the deformed state. The ECG signal waveform collected in the deformed state is compared with the natural state. Glitch and noise Not high, the composite film provided by the present invention has the advantages of high signal collection reliability, simple operation, and comfortable touch.

The above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: The technical solutions are modified, or some of the technical features are equivalently replaced; these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (20)

1. An elastic conductor composite film, which is characterized by comprising: a base film layer and a coating material coated on the surface of the base film layer, wherein the base film layer is an electrospun thermoplastic elastomer, and the coating material is a melting point Liquid metal below room temperature.
2. The elastic conductor composite film of claim 1, wherein a nano-silver conductive layer is formed between the base film layer and the coating material.
3. The elastic conductor composite film according to claim 1, wherein the elastic conductor composite film has a multi-layer structure, which is formed by alternately stacking the base film layer and the coating material in a vertical manner.
4. The elastic conductor composite film according to claim 1 or 2, wherein the elastic conductor composite film has a multilayer structure, and the base film layer, the nano silver conductive layer, and the coating material alternate in sequence. Stacked vertically.
5. The elastic conductor composite film of claim 1, wherein the coating material passes through a patterned mold to form the pattern on the surface of the base film layer.
6. The elastic conductor composite film according to claim 1, wherein a layer of ion conductive hydrogel is also covered on the contact surface of the elastic conductor composite film and the living body, and the pattern formed by the ion conductive hydrogel is consistent with The pattern formed by the coating material on the covered surface is consistent.
7. The elastic conductor composite film according to claim 1, wherein the electrospunable thermoplastic elastomer is a styrene-butadiene-styrene block copolymer, and the electrospunable thermoplastic elastomer is formed in The mass percentage concentration in the electrospinning polymer solution is 5wt%-20wt%.
8. The elastic conductor composite film of claim 1, wherein the liquid metal is a room temperature liquid gallium-based alloy.
9. A method for preparing an elastic conductor composite film, which is characterized in that it comprises:

   Step S1. Dissolve the electrospun thermoplastic elastomer in the intermediate agent to form an electrospun polymer solution;

   Step S2. Perform electrospinning using the electrospinning polymer solution, and collect electrospinning on the substrate to form the base film layer of the elastic conductor composite film;

   Step S3. Coating a coating material on the surface of the base film layer, wherein the coating material is a liquid metal with a melting point lower than room temperature.
10. The method for preparing an elastic conductor composite film according to claim 9, characterized in that, before the step S3, it further comprises:

    The base film layer is sequentially immersed in nano silver solution, reducing agent and absolute ethanol so that a nano silver conductive layer is formed on the surface of the base film layer.
11. The method for preparing an elastic conductor composite film according to claim 9, characterized in that, after the step S3, it further comprises:

    Use the electrospun polymer solution to electrospin a new base film layer on the surface where the base film layer has been coated with the coating material, and coat the coating material on the surface of the new base film layer, and so on The electrospinning and the coating of the coating material are alternately performed until an elastic conductor composite film with the required number of layers and a multilayer structure is obtained.
12. The method for preparing an elastic conductor composite film according to claim 10, characterized in that, after the step S3, it further comprises:

    The polymer solution is used to electrospin a new base film layer on the surface where the base film layer has been coated with the coating material, and a nano-silver conductive layer and the coating material are sequentially formed on the surface of the new base film layer, By analogy, electrospinning, nano-silver conductive layer formation and coating material coating are alternately performed until the required number of layers is obtained to form a multilayer structured elastic conductor composite film.
13. The method for preparing an elastic conductor composite film according to claim 10, wherein forming the nano-silver conductive layer on the surface of the base film layer comprises:

    Soak the base film layer in the nano silver solution for 5 minutes, take out the base film layer and place it in the air to dry naturally at room temperature. The air-dried base film layer is soaked in the reducing agent for no less than 5 minutes, and the base film layer soaked in the reducing agent is placed. Soak in absolute ethanol for no less than 10 minutes, take the base film layer soaked in absolute ethanol and place it in the air at room temperature to dry naturally, so that the nano-silver conductive layer is formed on the surface of the base film layer.
14. The method for preparing an elastic conductor composite film according to claim 10, wherein the nano silver solution is prepared by dissolving silver trifluoroacetate in ethanol to obtain a solution with a concentration of 0.1-1 g/mL.
15. The method for preparing an elastic conductor composite film according to claim 10, wherein the reducing agent is an ethanol solution of hydrazine hydrate.
16. The method for preparing an elastic conductor composite film according to claim 9, wherein coating the coating material on the surface of the base film layer comprises:

    A mold with a pattern is placed on the surface of the base film layer so that the coating material forms the pattern when the surface of the base film layer is coated.
17. The method for preparing an elastic conductor composite film according to claim 9, wherein the preparation method further comprises:

    A layer of ion conductive hydrogel is covered on the side of the elastic conductor composite film to be in contact with the biological body, and the pattern formed by the ion conductive hydrogel is consistent with the pattern formed by the coating material on the covered surface.
18. The method for preparing an elastic conductor composite film according to claim 9, wherein the step S1 comprises:

    The intermediate agent is ethylene dichloride, and the styrene-butadiene-styrene block copolymer is dissolved in ethylene dichloride to obtain an electrospinning polymer solution, and the mass percentage concentration in the formed electrospinning polymer solution It is 5wt%-20wt%.
19. The method for preparing an elastic conductor composite film according to claim 9, wherein the liquid metal is a room temperature liquid gallium-based alloy.
20. The method for preparing an elastic conductor composite film according to claim 9, wherein the thickness of the base film layer is positively correlated with the collection time of the electrospinning on the substrate.

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