An anisotropic paste conductive composite prepared by a blending method and a preparation method and application thereof

Abstract

The application belongs to the field of flexible electronic materials, and particularly relates to an anisotropic paste conductive composite prepared by a blending method, a preparation method and application thereof. The raw material composition of the paste conductive composite comprises the following components: a polymer matrix material, multi-walled carbon nanotubes and silver nanosheets. The polymer matrix material is obtained by heating reaction of polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer, isophorone diisocyanate and a catalyst at 50-70 DEG C for 10-14 h. The application further provides a preparation method of the paste electrode material. The paste electrode material can be used for collecting electrophysiological signals on various complex biological tissue surfaces, and overcomes the problems of signal distortion or loss due to the rough and complex surface, the tedious step of removing hair for detecting electrophysiological signals in a hairy area and the like in the prior art.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of flexible electronic materials, and particularly relates to an anisotropic paste-like conductive composite material prepared by a blending method and a preparation method and application thereof. BACKGROUND

[0002] Electrophysiological signals reflect the state of the human body, and a stable human-machine interface is essential to improve the accuracy and precision of detecting physiological signals. With the development of flexible sensors, the reliable electrical connection of the human-machine interface of the convenient electrophysiological monitoring equipment is increasingly needed. In order to meet the needs of electrophysiological monitoring, people have developed various flexible electrodes. One of the key features of these electrodes is to form a conformal and seamless contact with animal tissues or skin surfaces. However, when collecting electrophysiological signals on hairy skin surfaces, such as non-invasive detection of animal signals or electroencephalogram (EEG) on the head without shaving hair, it is often difficult to achieve such a full electrical connection.

[0003] The main role of using paste-like conductive materials is to maintain a stable electrical connection for a long time when facing various complex animal tissues or skin surfaces, so as to ensure that the electrophysiological monitoring equipment can continuously collect accurate electrophysiological signals. The present application develops a composite paste electrode by mixing a polymer matrix with conductive nanofillers. The paste electrode can be conformally coated on smooth or rough surfaces and has sufficient adhesion and the function of collecting electrophysiological signals. SUMMARY

[0004] In order to solve the above problems, the purpose of the present application is to overcome the adverse effects of the rough skin or tissue surface topography on the collection of electrophysiological signals, and to provide a stable electrical connection for the human-machine interface to improve the stability and reliability of the electrophysiological monitoring equipment.

[0005] In order to solve the above technical problems, the present application provides the following technical solutions:

[0006] The present application provides an anisotropic paste-like conductive composite material prepared by a blending method, which comprises a polymer matrix material, multi-walled carbon nanotubes and silver nanosheets; the polymer matrix material is obtained by heating reaction of polyethylene glycol polypropylene glycol polyethylene glycol block copolymer, isophorone diisocyanate (IPDI) and a catalyst at 50-70 DEG C for 10-14 h.

[0007] The polyethylene glycol polypropylene glycol polyethylene glycol block copolymer is purchased from sigma-aldrich, and the item number is 435465.

[0008] Preferably, the number average molecular weight (Mn) of the polyethylene glycol polypropylene glycol polyethylene glycol block copolymer is 4000-6000.

[0009] Preferably, the catalyst is selected from dibutyltin dilaurate (DBTDL).

[0010] Preferably, the diameter of the multi-walled carbon nanotube is 10-30 nm, and the length is 10-30 μm.

[0011] Preferably, the flake diameter of the silver nanosheet is 1-5 μm.

[0012] Preferably, the mass ratio of the polymer matrix material, the multi-walled carbon nanotube and the silver nanosheet is 18-22:0.5-1.5:10-14.

[0013] Preferably, the molar ratio of the polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer and isophorone diisocyanate is 1:1~1.1:1*10 -4 ~3*10 -4 .

[0014] The application also provides a preparation method of the anisotropic paste-like conductive composite prepared by the blending method.

[0015] S11: after dissolving the polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer, isophorone diisocyanate and a catalyst are added at room temperature (25±5℃), and the reaction is heated at 50-70℃ for 10-14 h to obtain a reaction liquid;

[0016] S12: the solvent in the reaction liquid is volatilized to obtain a polymer matrix material;

[0017] S13: the polymer matrix material and the multi-walled carbon nanotube are mixed for 160-200 s to obtain a mixture;

[0018] S14: the silver nanosheet is added to the mixture and mixed for 160-200 s, and then air-dried to obtain the anisotropic paste-like conductive composite prepared by the blending method.

[0019] Preferably, in the step S11, the polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer is purified by vacuum drying at 40℃ for 1-2 h before dissolving.

[0020] Preferably, in the step S11, the temperature for dissolving is 60℃, and the method is stirring.

[0021] Preferably, the polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer is dissolved in chloroform, and the mass ratio of the chloroform and the polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer is 2-4:1.

[0022] The water-washable paste electrode and the preparation method thereof include the following steps: (a) mixing purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) and isophorone diisocyanate (IPDI) in a chloroform solvent, and performing polymerization under the action of a catalyst to obtain a paste polymer matrix material; and (b) uniformly mixing the polymer matrix material, multi-walled carbon nanotubes and silver nanosheets by using a planetary mixer, and volatilizing the excess solvent.

[0023] Specifically, the preparation method of the anisotropic paste conductive composite prepared by using the blending method includes the following steps:

[0024] (1) vacuum drying poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (average Mn is 5800) at 40℃ for 1-2h to obtain purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol);

[0025] (2) dissolving the purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) in 3 times the mass of a solvent, stirring, and heating to 60℃ for sufficient dissolution; adding isophorone diisocyanate (IPDI) and a catalyst dropwise at room temperature, wherein the molar ratio of the purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) to the isophorone diisocyanate (IPDI) is 1:1.03, stirring, heating to 60℃ for 12h, cooling, pouring into an evaporating dish, stirring at room temperature in a fume hood for 72h, and volatilizing the solvent to obtain the component A.

[0026] (3) adding 20 parts by mass of the component A into a PE material mixing tank (30mL), and then adding 1 part by mass of the multi-arm carbon nanotube into the mixing tank.

[0027] (4) opening the mixing tank, adding 12 parts by mass of the silver nanosheet into the mixing tank, and then sealing the mixing tank and placing it into a planetary mixer for stirring for 180s.

[0028] (5) placing the uniformly mixed composite material in a ventilated environment for drying, and then directly taking out and using.

[0029] The application further provides a general-purpose water-washable paste electrode for electrophysiological signal monitoring, which contains the anisotropic paste conductive composite prepared by using the blending method.

[0030] Compared with the prior art, the technical scheme of the application has the following advantages:

[0031] The paste conductive composite material has high polymer chain segments, high cross-linking degree and viscosity of the high polymer matrix material, and a reliable conductive network is constructed by using one-dimensional and two-dimensional nano conductive fillers, the amount of the nano fillers is effectively reduced, and excellent electro-physiological signal transmission quality is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The figure is a comparison chart of signal crosstalk of the paste composite material of Example 1 and commercial gel material.

[0033] Figure 2 The figure is a comparison chart of adhesion performance of the paste composite material of Example 1 and commercial gel material and commercial patch electrode.

[0034] Figure 3 The figure is a photo of the high polymer matrix material.

[0035] Figure 4 The figure is a viscosity curve of the high polymer matrix material.

[0036] Figure 5 The figure is a preparation flow chart of the anisotropic paste conductive composite material prepared by using a blending method.

[0037] Figure 6 The figure is a loss modulus and storage modulus curve of the composite material prepared in Example 1.

[0038] Figure 7 The figure is a distribution chart of the conductive filler in the high polymer matrix material. DETAILED DESCRIPTION

[0039] The application will be further described below in combination with the drawings and specific examples, so that those skilled in the art can better understand the application and implement it, but the examples are not used as a limitation to the application.

[0040] Example 1

[0041] An anisotropic paste conductive composite material prepared by using a blending method has the following steps:

[0042] (1) Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (average Mn is 5800) is vacuum dried at 40℃ for 2h to obtain purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol);

[0043] (2) The purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) is dissolved in 3 times the mass of solvent chloroform, stirred, heated to 60°C to dissolve completely, and isophorone diisocyanate (IPDI) and a catalyst are added dropwise at room temperature 25°C, wherein the molar ratio of the purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) to isophorone diisocyanate (IPDI) is 1:1.03:2*10 -4 , stirred, heated to 60°C for 12h, cooled, poured into an evaporating dish, stirred at room temperature in a fume hood for 72h, and the solvent was volatilized to obtain a high molecular matrix material;

[0044] (3) 10g of the high molecular matrix material is added to a PE material mixing tank (30mL), followed by adding 0.5g of multi-walled carbon nanotubes. Then the mixing tank is sealed and placed in a planetary mixer for stirring for 180s; the total mass of the counterweight system of the mixer is 500g, the revolution speed of the mixer is 1500r / min, and the rotation speed of the mixer is 1000r / min;

[0045] (4) The mixing tank is opened, 6g of silver nanosheets is added, and then the mixing tank is sealed and placed in a planetary mixer for stirring for 180s; the total mass of the counterweight system of the mixer is 500g, the revolution speed of the mixer is 1500r / min, and the rotation speed of the mixer is 1000r / min;

[0046] (5) The mixed composite material is placed in a fume hood for air drying.

[0047] Example 2

[0048] An anisotropic paste-like conductive composite material prepared by a blending method, the steps are as follows:

[0049] (1) Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (average Mn is 5800) is vacuum dried at 40°C for 2h to obtain purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol);

[0050] (2) The purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) is dissolved in 2-4 times the mass of solvent chloroform, stirred, heated to 60°C to dissolve completely, and isophorone diisocyanate (IPDI) and a catalyst are added dropwise at room temperature 25°C, wherein the molar ratio of the purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) to isophorone diisocyanate (IPDI) is 1:1.03:1*10 -4 , stirred, heated to 50°C for 10h, cooled, poured into an evaporating dish, stirred at room temperature in a fume hood for 72h, and the solvent was volatilized to obtain a high molecular matrix material;

[0051] (3) 9 g of the high molecular matrix material was added into a mixing tank made of PE, and then 0.25 g of multi-walled carbon nanotubes was added into the mixing tank. The diameter of the multi-walled carbon nanotubes was 10 nm, and the length was 10 μm;

[0052] Then, the mixing tank was sealed and placed into a planetary mixer for stirring for 160 s. The revolution speed of the mixer was 1500 r / min, and the rotation speed of the mixer was 1000 r / min.

[0053] (4) The mixing tank was opened, 5 g of silver nanosheets with a sheet diameter of 1 μm was added into the mixing tank, and then the mixing tank was sealed and placed into a planetary mixer for stirring for 180 s. The revolution speed of the mixer was 1500 r / min, and the rotation speed of the mixer was 1000 r / min.

[0054] (5) The mixed composite material was placed in a fume hood for air drying.

[0055] Example 3

[0056] An anisotropic paste-like conductive composite material prepared by a blending method, the steps are as follows:

[0057] (1) Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (average Mn is 5800) was vacuum dried at 40 °C for 2 h to obtain purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol);

[0058] (2) The purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) was dissolved in 4 times the mass of the solvent chloroform, stirred, and heated to 60 °C for sufficient dissolution. Isophorone diisocyanate (IPDI) and a catalyst were added dropwise at room temperature 25 °C, wherein the molar ratio of the purified poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) to isophorone diisocyanate (IPDI) was 1:1.03:3*10 -4 , stirred, heated to 70 °C for reaction for 14 h, cooled, poured into an evaporating dish, stirred at room temperature in a fume hood for 72 h, and the solvent was volatilized to obtain a high molecular matrix material;

[0059] (3) 11 g of the high molecular matrix material was added into a mixing tank made of PE, and then 0.75 g of multi-walled carbon nanotubes was added into the mixing tank. The diameter of the multi-walled carbon nanotubes was 30 nm, and the length was 30 μm;

[0060] Then, the mixing tank was sealed and placed into a planetary mixer for stirring for 200 s. The revolution speed of the mixer was 1500 r / min, and the rotation speed of the mixer was 1000 r / min.

[0061] (4) Open the mixing jar, add 7 g of silver nanoplatelets with a size of 5 μm into the mixing jar, then seal the mixing jar and put it into the planetary mixer to stir for 180 s; the revolution speed of the mixer is 1500 r / min, and the rotation speed of the mixer is 1000 r / min;

[0062] (5) Place the mixed composite material in a fume hood to air dry.

[0063] Application Example 1

[0064] Two points 10 cm apart are selected on the upper arm along the arm axis, and the anisotropic paste-like conductive composite material prepared in Example 1 of the present application is taken out as a paste-like electrode and uniformly applied to the selected two points, and a thin copper sheet is used as a receiving electrode to collect the human electromyogram (EMG) (Note: the thin copper sheet cannot be directly placed on the arm to collect the human electromyogram), and the thin copper sheet is placed on the surface of the uniformly applied paste-like electrode to be tightly adhered. After the electromyogram is collected and recorded, it is washed with pure water, and then a commercial electrode patch (purchased from HealForce) is attached to the same two positions for collecting the electromyogram under the same action. After calculation and comparison, the electromyograms collected by the two methods have comparable signal-to-noise ratios.

[0065] Application Example 2

[0066] The electroencephalogram of the human head position is monitored without removing the hair. Two points (10-20 cm apart) are selected in the area covered by the hair, and an appropriate amount of the paste-like electrode described in the present application is uniformly applied to the selected two points, and a thin copper sheet is used as a receiving electrode as in Application Example 1, and the thin copper sheet is placed on the paste-like electrode for connection. After the signal is collected and recorded, the application area can be removed by washing with clean water. Similarly, commercial electrode patches are attached to the selected two points for monitoring the electroencephalogram, and the commercial electrode patches cannot monitor any band of the electroencephalogram without removing any hair.

[0067] Application Example 3

[0068] The performance stability of the material is crucial for long-term monitoring of electrophysiological signals. Compared with the commercial gel with the same function on the market, the paste-like electrode of the present application shows more excellent long-term stability. Specific comparison measures are as follows:

[0069] (a) The paste-like electrode material and the commercial gel material are placed in the same environment, and the mass change of each is measured after 24 h. Due to the water loss of the commercial gel, the mass of the commercial gel is reduced to about 10% of the original after 24 h, while the mass of the paste-like electrode hardly changes.

[0070] (b) The paste electrode material and the commercial gel material are placed in the same environment, and the viscosity change of each is measured after 24 hours. The commercial gel becomes solid after 24 hours, while the viscosity of the paste electrode hardly changes.

[0071] Application Example 4

[0072] Signal crosstalk is also an important factor affecting the quality of electrophysiological signal acquisition. The skin impedance is measured by metal electrodes 2 mm apart. The paste electrode and the commercial gel material are evenly applied between the electrodes and the skin, and then the copper strip counter electrode is attached to the skin of the arm to measure the skin impedance. In the first test, two materials are applied separately on the two metal electrodes. In the second test, the entire area between the two metal electrodes is evenly coated (the two metal detection electrodes are connected by the coated paste electrode or commercial gel material). After comparison, it is found that the measured skin impedance of the commercial gel material decreases significantly when it is applied in whole, indicating that signal crosstalk caused by short circuit occurs. The paste electrode prepared by the present application does not have abnormal phenomenon.

[0073] In addition, the adhesion performance of the paste electrode material of the present application also has obvious advantages compared with the commercial electrode patch and the commercial gel material, which can ensure that the electrophysiological detection port is directly pressed on the paste electrode material without falling off and other situations, thereby causing unstable electrophysiological signal output.

[0074] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A method for preparing anisotropic paste-like conductive composite material using a blending method, characterized in that, Includes the following steps: S11: After dissolving the polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer, add isophorone diisocyanate and catalyst at room temperature, and heat at 50-70℃ for 10-14 h to obtain the reaction solution; S12: Evaporate the solvent in the reaction solution to obtain a polymer matrix material; S13: Mix the polymer matrix material and multi-walled carbon nanotubes for 160-200 s to obtain a mixture; S14: Add silver nanosheets to the mixture, mix for 160-200 s, and then air dry to obtain the anisotropic paste-like conductive composite material prepared by the blending method; the number average molecular weight of the polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer is 4000-6000; the catalyst is selected from dibutyltin dilaurate; the diameter of the multi-walled carbon nanotubes is 10-30 nm and the length is 10-30 μm; the diameter of the silver nanosheets is 1-5 μm; the mass ratio of the polymer matrix material, multi-walled carbon nanotubes and silver nanosheets is 18-22:0.5-1.5:10-14.

2. The preparation method according to claim 1, characterized in that, The molar ratio of polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer to isophorone diisocyanate is 1:1-1.

1.

3. The preparation method according to claim 1, characterized in that, The polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer is dissolved in chloroform, and the mass ratio of chloroform to polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer is 2-4:

1.

4. An anisotropic paste-like conductive composite material prepared by blending method according to any one of claims 1-3, characterized in that, It includes a polymer matrix material, multi-walled carbon nanotubes, and silver nanosheets; the polymer matrix material is obtained by reacting polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer, isophorone diisocyanate, and a catalyst at 50-70°C for 10-14 h.

5. A universal washable paste electrode for monitoring electrophysiological signals, characterized in that, It includes the anisotropic paste-like conductive composite material prepared by blending as described in claim 4.

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