Semiconductor hydrogel as well as preparation method and application thereof

Abstract

The invention discloses semiconductor hydrogel as well as a preparation method and application thereof. The semiconductor hydrogel is hydrogel obtained by ionic crosslinking of a water-soluble conjugated polymer with semiconductor performance, can be prepared into single-network semiconductor hydrogel and can also be compounded with an existing hydrogel network to form multi-network hydrogel, and the hydrogel with the semiconductor performance, the biological function and the mechanical performance is achieved. The semiconductor hydrogel is used as a semiconductor material to realize preparation of an electrochemical transistor, is further used for construction of a complementary logic circuit and detection and amplification of an electrophysiological signal, is expected to replace a traditional semiconductor and becomes a key material of a bioelectronic device.

Description

Technical Field

[0001] The invention relates to hydrogel, in particular to a semiconductor hydrogel and a preparation method thereof, as well as application of the hydrogel as a semiconductor material in logic circuits and electrophysiological signal detection, and belongs to the field of organic polymer functional materials. Background Art

[0002] Hydrogels are three-dimensional cross-linked hydrophilic polymer networks containing a large amount of water. Compared with rigid inorganic materials and organic polymers, the mechanical properties of hydrogels can be widely adjusted to adapt to different biological tissues, including cartilage, skin, muscle and brain. In addition, hydrogels have diverse structures and are easy to modify, showing excellent versatility in bioengineering. By modifying different functional groups, hydrogels can show special stimulus responsiveness and interfacial properties, and have been successfully used in sensors, brakes, coatings, acoustic detectors, optics and electronics.

[0003] Traditional hydrogels only have ionic conductivity but not electronic conductivity. The three-dimensional hydrophilic network makes hydrogels a good ionic conductor and a satisfactory biocompatible material. Therefore, hydrogels can effectively reduce the interfacial impedance between traditional metal electrodes and biological tissues, facilitating the collection of biological signals. However, the low conductivity and mobility of ions limit the signal amplitude, response speed and cutoff frequency of hydrogel-based electronic components. In order to improve the electronic conductivity of hydrogels, conductive micro-nanocomposites such as carbon materials and metal materials can be added to the matrix of hydrogels. Compared with inorganic composites, conductive polymers have significant advantages in mechanical flexibility, solution processability and biocompatibility. Therefore, conductive polymers, including poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), polypyridine (PPy) and polyaniline (PANI), have been used to mix with non-conductive hydrogels to form interpenetrating networks, thereby providing excellent electronic conductivity to the hydrogel system. With the improvement of conductivity, conductive hydrogels can be used to fabricate multifunctional electronic devices and improve sensing sensitivity.

[0004] Semiconductors play a vital role in electronics and are basic elements for switching, amplification, rectification and logic operations. The electrical properties of semiconductors can be switched between insulation and conductivity. Intrinsic organic semiconductors are insulating, and the conductivity of the organic semiconductor layer can be adjusted by doping. For hydrogel electronics, semiconductor hydrogels are the basis for building complex logic circuits based on hydrogels and realizing multiple functions. However, so far, there has been little research on semiconductor hydrogels, and the performance cannot meet the needs. Tolbert et al. designed a conjugated polyelectrolyte material, polyfluorene thiophene PFT with amphiphilic side chains, which can be dissolved in water and self-assembled into a gel. The rheological and optical properties of this material have been confirmed, but its electrical properties as a semiconductor have not been proven (J.Phys.Chem.B 2016,120,6215-6224). Similarly, Banerjee et al. mixed a hydrophilic amphiphilic compound containing a naphthalene diimide (NDI)-coupled peptide and a primary amine to achieve a two-component fluorescent-semiconductor hydrogel, but its semiconductor electrical properties have not yet been demonstrated (Langmuir 2016, 32, 13226-13233). Hayward et al. used ionic heterojunctions to demonstrate the basic functions of diodes and triodes and the feasibility of constructing logic circuits with hydrogels (Science 367, 773-776 (2020).). However, the ionic heterojunctions they used only have ionic conductivity, lack electronic conductivity, low mobility, and are not compatible with electronic circuits, limiting device performance and applications.

[0005] Therefore, to date, hydrogels have only been used as simple wires, resistors or capacitors, and semiconductor hydrogels with electrical properties have not yet been developed, and there is a lack of methods for preparing semiconductor hydrogels and their electronic devices. Therefore, constructing semiconductor hydrogels is of great significance for advancing hydrogel electronics. Summary of the invention

[0006] In view of the lack of semiconductor hydrogels with high electrical performance, the present invention provides a design and preparation method for semiconductor hydrogels, and obtains single-network and multi-network semiconductor hydrogels, which achieve excellent semiconductor performance and good mechanical properties. Based on this, the construction of semiconductor hydrogel complementary logic circuits and the detection and amplification of electrophysiological signals are realized.

[0007] The design ideas and principles of the present invention are:

[0008] 1. The main component of the hydrogel needs to be a conjugated polymer with semiconductor properties. This type of conjugated polymer has good water solubility (solubility greater than 3 mg / mL). Water-soluble conjugated polymers include conjugated polymers with cations in the skeleton and conjugated polymers with anionic side chains. Conjugated polymers with cations in the skeleton can realize the preparation of n-type semiconductor hydrogels. Similarly, p-type semiconductor hydrogels can also be prepared by conjugated polymers with anionic side chains.

[0009] 2. This type of conjugated polymer can exist stably in water through cross-linking and will not dissolve. Considering that chemical cross-linking will have a significant impact on the structure of the conjugated polymer, and thus affect the semiconductor performance, the cross-linking method chooses physical cross-linking that has less impact on the polymer. Considering the characteristics of water-soluble conjugated polymers containing ions, ionic cross-linking is selected for physical cross-linking. The principle of ionic cross-linking is to select anions with larger conjugated planes, which have stronger binding force with the main chain of cationic conjugated polymers, and thus thermodynamically replace the original counter-ions. When the binding force between the new anion and the cationic skeleton is greater than the binding force between the cationic skeleton and water, the polymer after ionic cross-linking will no longer dissolve in water. Similarly, cations with large conjugated planes have stronger binding force with the anionic side chains of conjugated polymers, and ionic cross-linking can be achieved.

[0010] 3. In order to further reduce the effect of ionic crosslinking on the structure and assembly behavior of conjugated polymers, the polymer can be first prepared into a dry solid and then ionic crosslinked.

[0011] 4. Conjugated polymers usually have poor mechanical properties. In order to improve the mechanical properties and biointerface properties of the hydrogel system, they can be compounded with traditional hydrogel networks to form multi-network hydrogels, thus achieving hydrogels with excellent semiconductor properties, biological functions and mechanical properties. Compared with inorganic and organic electronic devices, hydrogel electronic devices can achieve excellent matching with the interface of biological tissues, ensuring good ion permeability while achieving biological functions such as sensing, antibacterial and adhesion.

[0012] Based on the above design ideas, in a first aspect of the present invention, a method for preparing a single network semiconductor hydrogel is provided.

[0013] In the first step, a water-soluble conjugated polymer A is dissolved in water to obtain a homogeneous aqueous solution A', and an ionic crosslinker B is dissolved in water or an orthogonal solvent of the water-soluble conjugated polymer (such as dimethyl sulfoxide, methanol, tetrahydrofuran, etc.) to obtain a homogeneous solution B'.

[0014] In the second step, the aqueous solution A' is prepared into a dry film C by spin coating, drop coating or blade coating. The film C is immersed in a solution B' of a certain concentration for a certain period of time to allow the ion cross-linking reaction to proceed fully, and then washed with water to obtain a single network thin film hydrogel material D. To prepare D with a certain shape, the film C can be placed on a hot stage at a specific temperature, a hollow mask of a specific shape can be covered on the film C, a solution B' of a certain concentration can be sprayed on the surface of the mask, the mask can be removed, and the film can be washed with water to obtain a patterned single network thin film hydrogel material D.

[0015] The water-soluble conjugated polymer A can be a conjugated polymer with a cation-containing backbone, or a conjugated polymer with an anionic side chain, depending on the type of hydrogel required. The corresponding ionic crosslinking agent B is an anionic crosslinking agent or a cationic crosslinking agent.

[0016] Formula I shows a conjugated polymer with a cation-containing backbone. In order to ensure its good water solubility, it is preferred to select a structure in which the monomer fragment contains two cations and the counter ion is a chloride ion. Other conjugated groups can also ensure good water solubility, so the side chain is preferably a hydrophilic group.

[0017]

[0018] In Formula I, Ar 1 represents an aryl group, a heteroaryl group or other conjugated groups; Ar 2 Existence or absence, when Ar 2 When present, it represents an aryl, heteroaryl or other conjugated group; R 1 and R 2 The same or different, independently selected from hydrogen, halogen (F, Cl, Br, I), cyano, nitro, alkoxy, polyethylene glycol; n is a positive integer representing the degree of polymerization of the polymer, preferably 10-50.

[0019] The above-mentioned aryl group is preferably a C6-C30 aryl group, such as phenyl, biphenyl, naphthyl, anthracenyl and the like.

[0020] The above-mentioned heteroaryl group is preferably a C2-C26 heteroaryl group, such as pyridyl, thienyl, pyrazinyl, piperazinyl and the like.

[0021] The above-mentioned other conjugated groups are generally C2-C26 conjugated groups containing carbon-carbon double bonds, such as -C=C-, -C=CC=C-.

[0022] The above-mentioned alkoxy group is preferably a C1-C18 straight-chain or branched alkoxy group, and more preferably a C1-C9 straight-chain or branched alkoxy group.

[0023] The polyethylene glycol group is preferably a C2-C18 linear or branched polyethylene glycol group, and more preferably a C2-C14 linear or branched polyethylene glycol group.

[0024] The following are some typical examples of cationic conjugated polymers of formula I:

[0025]

[0026] The anionic crosslinking agent shown in Formula II must have good solubility in both water and cationic conjugated polymer orthogonal solvents, as well as a large anionic volume.

[0027]

[0028] In Formula II, Ar 3 represents a cycloalkyl group, an aryl group or a heteroaryl group, preferably a C3-C8 cycloalkyl group, a C6-C30 aryl group or a C2-C26 heteroaryl group; Y - represents an anion, which can be one or more, selected from COO - , SO3 - ,PO4 - , polystyrene sulfonate and other hydrophilic anions; X + represents a cation, which can be one or more, selected from Na + , K + , Ca 2+ ,Mg 2+ Hydrophilic cations.

[0029] The following are some typical examples of compounds of formula II:

[0030]

[0031] Wherein m represents the degree of polymerization, which is preferably a positive integer of 300-5000.

[0032] Formula III describes a conjugated polymer containing anionic side chains. The main chain structure of polythiophene can provide excellent p-type charge transfer performance semiconductor properties. The side chains are selected from anionic side chains to ensure good water solubility. The anionic side chains include connecting segments with the skeleton, anionic end groups and cationic counterions.

[0033]

[0034] In Formula III, R 3 and R 4 represents the same or different anionic side chains, wherein the connecting fragment with the backbone is selected from alkyl connecting chain, alkoxy connecting chain, polyethylene glycol connecting chain; the anionic terminal group is selected from carboxyl, sulfonyl, phosphate; the cationic counterion is selected from Na +, K + , Ca 2+ ,Mg 2+ etc. metal ions; n is a positive integer representing the degree of polymerization of the polymer, preferably 10-100.

[0035] The following are some typical examples of conjugated polymers containing anionic side chains represented by formula III:

[0036]

[0037] The corresponding cationic crosslinking agents include but are not limited to the following structures, wherein a is a positive integer, preferably 1-10.

[0038]

[0039] Based on the construction method of single-network hydrogel, in the second aspect of the present invention, a method for preparing multi-network semiconductor hydrogel is provided.

[0040] In order to achieve the multi-network hydrogel with semiconductor properties, biointerface properties and mechanical properties, the multi-network semiconductor hydrogel designed in the present invention comprises at least two types of hydrogel networks: a double-network or triple-network hydrogel composed of a matrix polymer and / or a biofunctional polymer and the water-soluble conjugated polymer A of the present invention.

[0041] The matrix polymer can be selected from hydrophilic polymers commonly used in hydrogels, which can maintain good water absorption. These matrix polymers can form hydrogels through free radical polymerization of water-soluble monomers E. Some examples of matrix polymers are given below, including polyacrylic acid (PAA), polyacrylamide (PAAM), poly (N-isopropylacrylamide) (PNIPAM), polyethylene glycol (PEG), polymethacrylate-2-hydroxyethyl ester (PHEMA):

[0042]

[0043] The biofunctional polymer can improve the biocompatibility and interfacial properties of the hydrogel, and enhance the antibacterial, anti-hemolytic, and adhesion properties of the hydrogel. Some examples of biofunctional polymers are given below: polyvinyl alcohol, chitosan, gelatin, methacrylic anhydride gelatin (GelMA), sodium alginate, agarose, etc. These polymers can achieve regulation of solubility in water when external conditions change (temperature, pH value, ions, etc.).

[0044] The matrix polymer is not soluble in water, and the conditions for the biofunctional polymer and the water-soluble conjugated polymer of the present invention to dissolve in water are also different. Therefore, the present invention uses the matrix polymer monomer and the biofunctional polymer to be first blended under specific conditions, and then the aqueous solution A' of the water-soluble conjugated polymer is added. In order to improve the semiconductor properties of the hydrogel, it is necessary to ensure the continuity of the conjugated polymer semiconductor electron transmission path.

[0045] The preparation method of the multi-network semiconductor hydrogel is given below:

[0046] In the first step, monomer E of the matrix polymer and / or the biofunctional polymer F and a crosslinking agent G, such as N,N'-methylenebisacrylamide, are added to water in a certain proportion, heated and stirred to dissolve, and filtered;

[0047] The second step is to add an initiator H, such as a photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, or a thermal initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride, to the cooled solution to obtain a solution I;

[0048] The third step is to mix the solution I with the aqueous solution A' of the water-soluble conjugated polymer in a certain proportion, place the mixture in a container or a mold, and cause a free radical polymerization reaction under specific conditions (ultraviolet light or a certain temperature) according to the type of the added initiator;

[0049] Step 4: ion exchange the polymerized material with an ion crosslinker solution B';

[0050] In the fifth step, the obtained multi-network semiconductor hydrogel J is washed with water.

[0051] In a third aspect of the present invention, a method for constructing transistors and logic circuits based on semiconductor hydrogels and applications in the field of bioelectronic devices are provided.

[0052] The semiconductor hydrogel provided by the present invention has hydrophilicity, interface characteristics and semiconductor characteristics, and is suitable for being used as a semiconductor layer of an electrochemical transistor to realize the switching and amplification functions of the transistor and the construction of a complex logic circuit.

[0053] Semiconducting hydrogel electrochemical transistors contain an insulating substrate, three electrodes, a semiconductor layer, an encapsulation layer, and an electrolyte (see Figure 7 ). The insulating substrate can be a rigid substrate such as silicon dioxide, glass, or a flexible substrate such as polyimide (PI) or polyethylene terephthalate (PET). The source and drain electrodes can be conductive electrodes such as gold, copper, silver, carbon nanotubes, silver nanowires, etc., and the gate electrode can be Ag / AgCl electrode or other reference electrode. Electrodes are processed on the substrate by photolithography and evaporation to obtain substrate K.

[0054] The semiconductor layer is the semiconductor hydrogel mentioned above. For the single network hydrogel D, it can be processed on the substrate K according to the preparation method of the single network semiconductor hydrogel mentioned above. For the multi-network hydrogel J, it can be processed on the substrate K according to the preparation method of the multi-network semiconductor hydrogel mentioned above, or the processed material can be transferred to the substrate K.

[0055] The wire part except the semiconductor layer and the gate is encapsulated, and the encapsulation layer can be epoxy resin SU8, polyparaxylene, etc. The electrolyte solution can be selected from 0.1M NaCl aqueous solution, phosphate buffer solution (PBS), etc. The semiconductor layer and the gate are covered with the electrolyte solution to obtain a semiconductor hydrogel electrochemical transistor.

[0056] Based on multiple semiconductor hydrogel electrochemical transistors with different carrier transport types, semiconductor hydrogel logic circuits such as inverters, NAND gates, and NOR gates can be prepared (see Fig.11 ). The processing method is similar to that of a single transistor, and transistors in different positions need to be processed with semiconductors of corresponding polarity.

[0057] The signal inversion area of ​​the inverter can amplify the input small signal by multiples and then output it, so it can be used as a signal amplifier. The circuit of the signal amplifier is as follows Fig.11 As shown in the inverter in FIG, it is usually prepared on a flexible substrate and includes an n-type electrochemical transistor with an n-type semiconductor hydrogel as a semiconductor layer and a p-type electrochemical transistor with a p-type semiconductor hydrogel as a semiconductor layer. Due to the excellent biocompatibility of hydrogels, signal amplifiers based on semiconductor hydrogels are expected to achieve detection and amplification of electrophysiological signals. Here is a method for detecting and amplifying electrophysiological signals based on semiconductor hydrogel logic devices.

[0058] The electrophysiological signals on the human body surface include electrooculography, electrocardiography, electroencephalography and electromyography. The amplitude of these signals is small, less than 1mV, so direct detection is difficult. By placing the semiconductor hydrogel signal amplifier on the human skin, applying saline or solid gel electrolyte at the contact position, and using the human body as a gate, the surface electrical signals can be detected, amplified and output. Thereby achieving the detection and amplification of electrophysiological signals. The amplitude of the mouse cerebral cortex signal is very small, the frequency is high, and the brain tissue is relatively soft, making the interface between the device and the brain tissue very important. The mechanical properties of the hydrogel semiconductor layer match the brain tissue, and the water content is high, which meets the ion permeability in the cerebrospinal fluid environment. The interface can fit tightly with the brain tissue to achieve good collection and amplification of the cerebral cortex signal.

[0059] In summary, the present invention provides a high-performance semiconductor hydrogel and a preparation method thereof, as well as applications in the field of electrophysiological signal detection. Semiconductor hydrogels are expected to replace traditional semiconductors and become key materials for bioelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 Schematic diagram of the structure and function of the semiconductor hydrogel of the present invention.

[0061] Figure 2 Schematic diagram of the single-network semiconductor hydrogel construction method designed for the present invention.

[0062] Figure 3 Schematic diagram of the multi-network semiconductor hydrogel structure designed for the present invention.

[0063] Figure 4 These are photos of the cationic conjugated polymer 1 and the prepared single-network semiconductor hydrogel 2 in Example 1 of the present invention, wherein the left picture shows the cationic conjugated polymer 1 solution in the bottle and the prepared block-shaped single-network semiconductor hydrogel 2, and the right picture shows the prepared patterned single-network semiconductor hydrogel 2.

[0064] Figure 5 The water content of the semiconductor hydrogels 2, 3, and 4 prepared in the examples of the present invention (wherein the percentage is the mass fraction of the cationic conjugated polymer 1).

[0065] Figure 6 The fracture stress and fracture strain of multi-network semiconductor hydrogels 3 and 4 prepared in accordance with the present invention with different proportions of cationic conjugated polymer 1.

[0066] Figure 7 This is a schematic diagram of the structure of the semiconductor hydrogel electrochemical transistor prepared in Example 5 of the present invention.

[0067] Figure 8 For Figure 7 The transfer curves of semiconductor hydrogels 2, 3, and 4 measured by the device shown in FIG. DS is the source-drain current, V GS is the gate voltage).

[0068] Fig. 9 For Figure 7 The output curves of semiconductor hydrogels 2, 3, and 4 measured by the devices shown in FIG. DS is the source-drain voltage, I DS is the source-drain current, V GS is the gate voltage).

[0069] Fig.10 For Figure 7 The transfer curve of the p-type semiconductor hydrogel 6 measured by the device shown in FIG. DS is the source-drain current, V GS is the gate voltage).

[0070] Fig.11Schematic diagram of semiconductor hydrogel logic circuit constructed in Example 7 of the present invention, including inverter, NAND gate and NOR gate (where V In 、V A 、V B is the input voltage, V Out is the output voltage, GND is the ground).

[0071] Fig.12 The characteristic curves of the semiconductor hydrogel inverter, NAND gate and NOR gate constructed in Example 7 of the present invention (where V In 、V A 、V B is the input voltage, V Out is the output voltage).

[0072] Fig.13 The frequency response curve of the semiconductor hydrogel inverter constructed in Example 7 of the present invention (where V In is the input voltage, V Out is the output voltage).

[0073] Fig.14 The live and dead conditions of human keratinocytes cultured on semiconductor hydrogels 2, 3, and 4 in Example 8 of the present invention are shown, wherein green represents live cells after staining, and the scale is 100 micrometers.

[0074] Fig.15 This is a schematic diagram of the flexible semiconductor hydrogel amplifier prepared in Example 9 of the present invention.

[0075] Fig.16 This is a comparison between a human electrocardiogram measured by a flexible semiconductor hydrogel amplifier in Example 10 of the present invention and a commercial gel electrode.

[0076] Fig.17 This is a graph of electrical signals of the mouse cerebral cortex measured by a flexible semiconductor hydrogel amplifier according to Example 10 of the present invention (where Normalized Amp is the normalized amplitude). DETAILED DESCRIPTION

[0077] The present invention will be further described in detail below through embodiments in conjunction with the accompanying drawings, but the scope of the present invention is not limited in any way.

[0078] Example 1

[0079]

[0080] Preparation method of single network semiconductor hydrogel 2: Dissolve the water-soluble cationic conjugated polymer 1 in water to obtain a 3 mg / mL solution. Dissolve sodium 1,3-dibenzenesulfonate (DBS) in water to obtain a 3 mg / mL DBS / H2O solution. Dissolve sodium 1,3-dibenzenesulfonate in dimethyl sulfoxide to obtain a 0.3 mg / mL DBS / DMSO solution. Mix the polymer aqueous solution and DBS / H2O to obtain a bulk single network semiconductor hydrogel 2. Spin coat the polymer aqueous solution into a thin film, immerse it in DBS / DMSO for 5 minutes, wash with water, and blow dry to obtain a thin film single network semiconductor hydrogel 2. Spin coat the polymer aqueous solution into a thin film, cover it with a mask, spray DBS / H2O solution on a 100°C hot stage, wash with water, and blow dry to obtain a patterned single network semiconductor hydrogel 2. The prepared bulk single network semiconductor hydrogel 2 and patterned thin film single network semiconductor hydrogel 2 are shown in FIG. Figure 4 .

[0081] Example 2

[0082]

[0083] In this embodiment, two multi-network semiconductor hydrogels were prepared, the components of which are shown in the table above, and which can be obtained by thermal polymerization and crosslinking of aqueous solutions. Among them, multi-network semiconductor hydrogel 4 contains N-hydroxysuccinimide groups, which can achieve good biointerface adhesion.

[0084] Preparation method of multi-network semiconductor hydrogel 3: Add polyvinyl alcohol to water (10 mg / mL), heat and stir at 95°C to dissolve, and filter. Add 92 mg of acrylamide, 4 mg of N,N'-methylenebisacrylamide and 6 mg of 2,2'-azobis(2-methylpropionamidine) dihydrochloride to the cooled 2 mL polyvinyl alcohol solution. Mix the above solution with the aqueous solution of cationic conjugated polymer 1 (3 mg / mL) in a certain volume ratio, heat on a 70°C hot plate for 30 minutes, soak in 3 mg / mL DBS / DMSO solution for 5 minutes, and dry to obtain multi-network semiconductor hydrogel 3.

[0085] Preparation method of multi-network semiconductor hydrogel 4: 300 mg acrylic acid, 100 mg gelatin, 10 mg N-hydroxysuccinimide acrylate and 1 mg gelMA were added to 1 mL of water, heated and stirred at 60 ° C to dissolve, and filtered. 2 mg of 2,2'-azobis(2-methylpropionamidine) dihydrochloride was added to the cooled solution. The above solution was mixed with an aqueous solution of cationic conjugated polymer 1 (3 mg / mL) according to a certain volume ratio, heated on a 70 ° C hot stage for 30 minutes, soaked in 3 mg / mL DBS / DMSO solution for 5 minutes, and dried to obtain multi-network semiconductor hydrogel 4.

[0086] Example 3

[0087] Characterization of water content of semiconductor hydrogel. The completely dehydrated semiconductor hydrogels 2, 3, and 4 were obtained by heating and drying, and their weights were measured. Then, they were allowed to absorb water repeatedly and their weights were measured. The water content was calculated to be (nm) / m. Figure 5 The water content of the single-network semiconductor hydrogel is about 40%, while the water content of the multi-network semiconductor hydrogel is higher than 60%.

[0088] Example 4

[0089] Characterization of mechanical properties of semiconductor hydrogels. The multi-network semiconductor hydrogel was thermally polymerized on the surface of SiO2 / Si sheet modified with octadecyltrimethoxysilane. The semiconductor hydrogel block material was then peeled off and re-absorbed with water, and then tensile tested using Shimadzu EZ LX. The mechanical properties of multi-network hydrogels 3 and 4 with different cationic conjugated polymer ratios are shown in Figure 6 The multi-network semiconductor hydrogel can retain the good tensile properties brought by the matrix polymer. With the increase of the conjugated polymer content, the fracture stress of multi-network semiconductor hydrogels 3 and 4 remains basically unchanged, and the stretchable properties gradually decrease.

[0090] Example 5

[0091] Construction of semiconductor hydrogel transistors and characterization of semiconductor properties. Using silicon dioxide as a substrate, gold electrodes were processed as source and drain electrodes by photolithography and evaporation stripping. Two layers of polyparaxylene were chemically vapor deposited. The channel was patterned by reactive ion etching. For a single-network semiconductor hydrogel, an aqueous solution of cationic conjugated polymer 1 was spin-coated as a thin film, immersed in a DBS / DMSO solution for 5 minutes, washed with water, blown dry, and the sacrificial layer of polyparaxylene was torn off to obtain a single-network semiconductor hydrogel transistor. For a multi-network semiconductor hydrogel, the solution described in Example 2 was drop-coated on the channel, heated and polymerized on a hot plate at 70°C for 30 minutes, immersed in DBS / DMSO for 5 minutes, washed with water, blown dry, and the sacrificial layer of polyparaxylene was torn off to obtain a multi-network semiconductor hydrogel transistor. A 0.1M NaCl solution was dripped on the channel, an external Ag / AgCl gate electrode was connected, and the transfer curve, transmission curve and transient response behavior of the transistor were tested using an Fs-Pro PDA semiconductor tester. The structure of the semiconductor hydrogel electrochemical transistor can be seen in Figure 7 , the transfer curve is shown in Figure 8 , output curve see Fig. 9 .

[0092] Single-network semiconductor hydrogel electrochemical transistors exhibit excellent device performance, with characteristic parameter μC* values ​​reaching 120 F cm -1 V -1 s -1, the on / off ratio reaches 10 7 The response time is in the millisecond level, which is a leading position in organic electrochemical transistor materials. Multi-network semiconductor hydrogels 3 and 4 give hydrogels good mechanical properties while maintaining semiconductor properties. The normalized μC* exceeds 100F cm -1 V -1 s -1 , which is close to that of single-network hydrogel. As the overall thickness of multi-network semiconductor hydrogel increases, the response time of the device increases tenfold.

[0093]

[0094] Note: # The marked data are the mass fraction of cationic conjugated polymer 1 in the multi-network semiconductor hydrogel.

[0095] Example 6

[0096]

[0097] Preparation method of p-type semiconductor hydrogel 6: Dissolve the water-soluble p-type polymer 5 in water to obtain a 3 mg / mL solution. Dissolve the dicationic compound in dimethyl sulfoxide to obtain a 0.3 mg / mL DMSO solution. Spin-coat the polymer aqueous solution into a thin film, immerse it in a DMSO solution containing the dicationic compound in the above formula for 5 minutes, wash with water, and blow dry to obtain a thin film p-type semiconductor hydrogel 6. The p-type semiconductor hydrogel electrochemical transistor was prepared by the same method as in Example 5, showing excellent p-type device performance, and its transfer curve is shown in FIG. Fig.10 .

[0098] Example 7

[0099] Construction of semiconductor hydrogel logic circuit. Inverters, NAND gates and NOR gates were prepared using p-type semiconductor hydrogel 6 and n-type semiconductor hydrogel 2 or 4. The processing method is similar to that of a single transistor. First, gold source and drain electrodes are processed on the substrate, and then polyparaxylene is processed twice for reactive ion etching patterning. P-type or n-type semiconductor hydrogels are processed at different transistor channels respectively. Finally, the polyparaxylene layer is torn off for patterning. The function of the logic device is tested. The circuit diagram of the inverter, NAND gate and NOR gate is shown in Fig.11 , characteristic curve see Fig.12, where the p-type hydrogel is a single-network hydrogel 6, and the n-type hydrogel is a single-network hydrogel 2. The inverter deflects at a voltage of about 0.5V, the maximum gain can reach more than 250, and the maximum power consumption is less than 1 microwatt, which has outstanding performance among organic semiconductor inverters. The NAND gate and AND-OR gate composed of four transistors can both complete the corresponding logical operations. These results prove that semiconductor hydrogels can realize the basic functions of logic circuits and promote the development of hydrogel electronics. Since the voltage flipping interval of the inverter can be used as a signal amplifier to amplify small AC signals. We verified the frequency response of the semiconductor hydrogel amplifier, see Fig.13 , where the p-type hydrogel is a single network hydrogel 6 and the n-type hydrogel is a single network hydrogel 2. It was found that it can achieve AC signal amplification in the range of 1 Hz to 100 Hz.

[0100] Example 8

[0101] Biocompatibility of semiconductor hydrogels. Semiconductor hydrogels 2, 3, and 4 were loaded into a cell well plate, and human keratinocytes were cultured in the well plate. After 24 hours, they were stained with dyes. Live cells emitted green fluorescence, and dead cells emitted red fluorescence. They were observed under a fluorescence microscope. The live and dead cells were shown in Fig.14 There was no cell death, proving that semiconductor hydrogels have low cytotoxicity and good biocompatibility, and are suitable for in situ signal detection on the surface and in vivo of organisms.

[0102] Example 9

[0103] Construction of semiconductor hydrogel flexible amplifier. In order to test electrophysiological signals in situ, a semiconductor hydrogel-based flexible amplifier was fabricated. The device schematic is shown in Fig.15 . Spin-coat a polyimide solution on a Si substrate and heat-dry under nitrogen to obtain a polyimide film. Prepare a gold electrode by photolithography and evaporation. Encapsulate the wires with SU8, and process and pattern the p-type semiconductor hydrogel 6 and the n-type semiconductor hydrogel 2 or 4, respectively.

[0104] Example 10

[0105] The semiconductor hydrogel flexible amplifier is used to detect and amplify electrophysiological signals. The semiconductor hydrogel flexible amplifier obtained in Example 9 can be used to detect electrophysiological signals. The human electrocardiogram (ECG) signal and the mouse cerebral cortex signal (ECoG) signal were tested. Fig.16 and Fig.17. Among them, hydrogel 4 was used as the n-type semiconductor hydrogel in the device for ECG signal testing, and hydrogel 2 was used as the n-type semiconductor hydrogel in the device for cerebral cortex signal testing. In the ECG signal test, the flexible device was attached to the left chest of the person, a constant bias voltage was applied, the right shoulder blade was grounded, and the output signal of the amplifier was tested. Since semiconductor hydrogel 4 contains adhesion functional groups, it can fit well with human skin. Compared with traditional gel electrodes, the flexible amplifier based on semiconductor hydrogel can amplify the amplitude of ECG signals by more than 50 times. In the mouse cerebral cortex test, the mouse brain was depilated, the scalp was cut, and the skull was drilled. The flexible device was placed in the right lower brain area, and the Ag / AgCl electrode was inserted into the left upper brain area for grounding. The mouse cerebral cortex signal was tested and obtained. Compared with the Ag / AgCl electrode, the signal was amplified by more than 25 times, and the signal-to-noise ratio was significantly improved. It is proved that the semiconductor hydrogel flexible amplifier can realize the effective detection of tiny electrophysiological signals and has broad application prospects in the field of bioelectronics.

Claims

1. A semiconductor hydrogel, characterized in that: The semiconductor hydrogel contains a hydrogel prepared by ion crosslinking a water-soluble conjugated polymer with semiconductor properties. The water-soluble conjugated polymer with semiconductor properties is a conjugated polymer with a cation in the skeleton or a conjugated polymer with an anion side chain.

2. The semiconductor hydrogel according to claim 1, characterized in that The semiconductor hydrogel comprises a hydrogel prepared by ion crosslinking of a cationic conjugated polymer represented by Formula I and an anionic crosslinking agent represented by Formula II; In Formula I, Ar 1 represents an aryl group, a heteroaryl group or other conjugated groups; Ar 2 Existence or absence, when Ar 2 When present, it represents an aryl, heteroaryl or other conjugated group; R 1 and R 2 are the same or different and are independently selected from hydrogen, halogen, cyano, nitro, alkoxy, and polyethylene glycol; n is a positive integer representing the degree of polymerization of the polymer; In Formula II, Ar 3 represents a cycloalkane group, an aryl group or a heteroaryl group; Y - represents one or more hydrophilic anions, X + represents one or more hydrophilic cations.

3. The semiconductor hydrogel according to claim 2, characterized in that In Formula I and Formula II, the aryl group is a C6-C30 aryl group, the heteroaryl group is a C2-C26 heteroaryl group, the other conjugated group is a C2-C26 conjugated group containing a carbon-carbon double bond, the alkoxy group is a C1-C18 alkoxy group, the polyethylene glycol group is a C2-C18 polyethylene glycol group, and the cycloalkyl group is a C3-C8 cycloalkyl group.

4. The semiconductor hydrogel according to claim 2, characterized in that The cationic conjugated polymer represented by formula I is selected from one or more of the following polymers:

5. The semiconductor hydrogel according to claim 2, characterized in that The anionic crosslinking agent shown in formula II is selected from one or more of the following compounds: Where m represents the degree of polymerization.

6. The semiconductor hydrogel according to claim 1, characterized in that The semiconductor hydrogel comprises a conjugated polymer with anionic side chains represented by formula III and a cationic crosslinking agent, and the hydrogel is prepared by ionic crosslinking; In Formula III, R 3 and R 4 represents the same or different anionic side chains, the anionic side chains include a connecting segment with the backbone, an anionic terminal group and a cationic counterion, wherein the connecting segment with the backbone is independently selected from an alkyl connecting chain, an alkoxy connecting chain, and a polyethylene glycol connecting chain, the anionic terminal group is selected from a carboxyl group, a sulfonyl group, and a phosphate group, and the cationic counterion is a metal ion; n is a positive integer representing the degree of polymerization of the polymer.

7. The semiconductor hydrogel according to claim 6, characterized in that The conjugated polymer with anionic side chains shown in formula III is selected from one or more of the following polymers:

8. The semiconductor hydrogel according to claim 6, characterized in that The cationic crosslinking agent is selected from one or more of the following compounds: Where a is a positive integer.

9. The semiconductor hydrogel according to claim 1, characterized in that The semiconductor hydrogel is a single-network hydrogel, which contains only a single network formed by ionic crosslinking of a water-soluble conjugated polymer with semiconductor properties; or, the semiconductor hydrogel is a multi-network hydrogel, which, in addition to the network formed by ionic crosslinking of a water-soluble conjugated polymer with semiconductor properties, also has hydrogel networks formed by one or more other polymers.

10. The semiconductor hydrogel according to claim 9, characterized in that The other polymers are hydrophilic polymers commonly used in hydrogels, including but not limited to: polyacrylic acid, polyacrylamide, poly(N-isopropylacrylamide), polyethylene glycol, poly(2-hydroxyethyl methacrylate); or are biofunctional polymers, including but not limited to: polyvinyl alcohol, chitosan, gelatin, methacrylic anhydride gelatin, sodium alginate, and agarose.

11. A method for preparing a single network semiconductor hydrogel, comprising the following steps: 1a) dissolving a water-soluble conjugated polymer having semiconductor properties in water to obtain a homogeneous aqueous solution A'; dissolving an ionic crosslinking agent in water or an orthogonal solvent of the conjugated polymer to obtain a homogeneous solution B'; 1b) preparing the aqueous solution A' into a dry film C, then immersing the film C in the solution B' for a period of time to allow the ionic cross-linking reaction to proceed fully, washing with water, and obtaining a single network thin film semiconductor hydrogel material; or, placing the film C on a hot stage, covering it with a hollow mask of a specific shape, spraying the solution B' on the surface of the hollow mask, removing the hollow mask, and washing with water to obtain a patterned single network thin film semiconductor hydrogel material.

12. A method for preparing a multi-network semiconductor hydrogel, comprising the following steps: 2a) dissolving one or more hydrophilic polymers or monomers and a cross-linking agent thereof in water, and adding an initiator to obtain a solution; 2b) mixing the solution obtained in step 2a) with a homogeneous aqueous solution A' of a water-soluble conjugated polymer having semiconductor properties, placing the mixture in a container or a mold, and causing a free radical polymerization reaction under specific conditions according to the type of the added initiator; 2c) The material obtained by polymerization in step 2b) is subjected to ion exchange with a solution B' of an ionic crosslinking agent, and washed with water to obtain a multi-network semiconductor hydrogel.

13. An electrochemical transistor comprising a substrate, a source electrode, a drain electrode, a gate electrode, a semiconductor layer, an encapsulation layer and an electrolyte, characterized in that: The material of the semiconductor layer is the semiconductor hydrogel according to any one of claims 1 to 10.

14. A logic circuit, characterized in that: The logic circuit contains a device using the semiconductor hydrogel according to any one of claims 1 to 10 as a semiconductor layer.

15. A signal amplifier is an inverter prepared on a flexible substrate, comprising an n-type transistor and a p-type transistor, characterized in that: The transistor is an electrochemical transistor, and the semiconductor layer material thereof is the semiconductor hydrogel according to any one of claims 1 to 10.

16. Use of the signal amplifier according to claim 15 in an electrophysiological signal detection system.

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