阅读说明：本技术 以丝素蛋白膜为柔性基底的瞬态电子器件及其制备方法 (Transient electronic device with silk fibroin film as flexible substrate and preparation method thereof ) 是由 白硕 王安河 陈炀 麻宇琦 韩青权 于 2020-04-26 设计创作，主要内容包括：本发明涉及一种以丝素蛋白膜为柔性基底的瞬态电子器件及其制备方法,该瞬态电子器件包括柔性基底和导电电路：柔性基底包括水溶性的再生丝素蛋白膜,导电电路包括银纳米线,且银纳米线通过将再生丝素蛋白溶液浇铸于银纳米线图案以转印于所述柔性基底。该瞬态电子器件具有高透光率、优异的力学性能和优异的绝缘性能,在任务完成后一分钟内即可溶解在水中。本发明还提供了相应的制备方法,采用两次溶液浇铸法,步骤简单易行,成本低廉,应用前景好,有望促进瞬态电子学在信息安全和可穿戴设备领域的发展和应用。(The invention relates to a transient electronic device taking a silk fibroin film as a flexible substrate and a preparation method thereof, wherein the transient electronic device comprises the flexible substrate and a conductive circuit: the flexible substrate comprises a water-soluble regenerated silk fibroin film, the conductive circuit comprises silver nanowires, and the silver nanowires are transferred to the flexible substrate by casting a regenerated silk fibroin solution on the silver nanowire pattern. The transient electronic device has high light transmittance, excellent mechanical property and excellent insulating property, and can be dissolved in water within one minute after a task is completed. The invention also provides a corresponding preparation method, adopts a two-time solution casting method, has simple and easy steps, low cost and good application prospect, and is expected to promote the development and application of transient electronics in the fields of information safety and wearable equipment.)

1. A transient electronic device with silk fibroin film as flexible substrate is characterized in that the transient electronic device comprises a flexible substrate and a conductive circuit;

the flexible substrate comprises a water-soluble regenerated silk fibroin film;

the conductive circuit includes silver nanowires that are transferred to the flexible substrate by casting a regenerated silk fibroin solution onto a silver nanowire pattern.

2. The transient electronic device of claim 1, wherein the regenerated silk fibroin film has a thickness of 50-260 μ ι η.

3. The transient electronic device of claim 1, wherein said regenerated silk fibroin is selected from one or a combination of more than two of regenerated mulberry silk fibroin, regenerated tussah silk fibroin, regenerated willow silk fibroin, regenerated tussah silk fibroin, regenerated castor silk fibroin, and regenerated silk fibroin.

4. A method for preparing a transient electronic device with a silk fibroin film as a flexible substrate is characterized by comprising the following steps:

s1, casting the silver nanowire dispersion liquid on a patterned template, and forming a silver nanowire pattern on the concave part of the patterned template after the solvent is completely evaporated;

and S2, casting the regenerated silk fibroin solution on a patterned template with a silver nanowire pattern, and drying to obtain the regenerated silk fibroin film, thus obtaining the flexible transient electronic device.

5. The method of claim 4, wherein in the step S1, the silver nanowire dispersion has a mass fraction of silver nanowires of 5-10%.

6. The method of claim 4, wherein in step S2, the regenerated silk fibroin solution has a concentration of 2-8%;

preferably, the thickness of the regenerated silk fibroin film is 50-260 μm.

7. The method of claim 4, wherein the silver nanowire dispersion is prepared in step S1 by: respectively preparing a polyvinylpyrrolidone solution and a metal chloride solution by using ethylene glycol as a solvent; dissolving silver nitrate in the polyvinylpyrrolidone solution, mixing with the metal chloride solution, uniformly stirring, reacting for 4-6 h at 120-150 ℃, and washing and concentrating to obtain silver nanowires; dispersing the silver nanowires in ethanol to obtain silver nanowire dispersion liquid;

preferably, the metal chloride is sodium chloride, potassium chloride, copper chloride or ferric chloride.

Preferably, after washing and concentrating, the method further comprises the following steps: the residue was removed with acetone and ethanol.

8. The method of claim 4, wherein in step S2, the method for preparing the regenerated silk fibroin solution comprises: pretreating silk with an alkali solution to obtain degummed silk fibers; dissolving the degummed silk fiber in an inorganic salt/alcohol/water ternary solvent system for dialysis; thus preparing the regenerated silk fibroin solution;

preferably, after dialysis, the method further comprises the following steps: the dialyzed solution was centrifuged to remove impurities.

9. The method of claim 8, wherein the ternary solvent system of inorganic salts/alcohols/water is selected from the group consisting of: calcium chloride/ethanol/water, calcium chloride/methanol/water, calcium nitrate/methanol/water or calcium nitrate/ethanol/water.

10. Use of the transient electronic device according to any of claims 1 to 3 or the method of manufacturing according to any of claims 4 to 9 in the field of wearable devices, biomedical sensors, implantable devices, smart apparel, medical tissue engineering.

Technical Field

The invention relates to the technical field of transient electronic devices, in particular to a transient electronic device taking a silk fibroin film as a flexible substrate and a preparation method thereof.

Background

The transient device can stably work within a set time after being prepared, and the device partially or completely disappears after being triggered under a specific condition, so that irreversible structural and functional damage is realized. By means of the characteristic that the transient device is destroyed and disappears, the transient device has important application value in the fields of taking-out-free implantable devices, degradable environment-friendly devices and information safety for preventing sensitive information from being leaked.

Compared with the traditional electronic device, the flexible transient electronic device can adapt to the uneven working surface, has the transient degradation characteristic and is beneficial to reducing the pollution of electronic wastes. In addition, when the flexible transient device is used as an implantable medical device, the flexible transient device can be in contact with human soft tissues without the risk of stress injury and secondary operation, so that the flexible transient device becomes a research hotspot in the fields of medical health, photoelectric energy conversion, information safety and the like.

To date, flexible electronic devices are prepared by transfer printing, 3D printing, physical and chemical deposition of inorganic conductor or semiconductor materials that can form ordered patterns or arrays on flexible substrates. In the biomedical field, degradable materials with good biocompatibility, such as polylactic acid, polycaprolactone, polylactic acid-glycolic acid copolymer, polysaccharide, protein and the like, have been developed at present as substrates for constructing flexible transient devices. But the degradation speed is very slow, and the degradation conditions of partial materials are too harsh, so that the practical application cannot be met. In addition, the light transmittance and the mechanical property of the film prepared by the material are difficult to simultaneously meet the structure and performance requirements of the flexible transient device.

Silk fibroin is a natural fiber protein, has good biocompatibility and biodegradability, and is widely applied to the field of biomedicine, such as surgical sutures, bone nails and gel materials. Compared with other biodegradable materials, the silk fibroin film has excellent mechanical property, optical property and electrical insulation property, and has wide application prospect of flexible electronic devices. In order to enable the insulating silk fibroin film to have conductive performance, a carbon-based material and metal nanoparticles are used as conductors, a patterning path is formed on the silk fibroin film through an etching and depositing method, or the whole electrode array is integrated on the silk fibroin film substrate through a PDMS stamp technology. In addition, with the development of 3D printing technology, people use liquid metal, carbon nanomaterials, and metal nanoparticles as printable conductive ink to directly write conductive patterns on the silk fibroin substrate. The research results of various processing techniques play an important role in promoting the development of flexible transient electronics. However, the preparation of flexible transient electrons based on silk fibroin membranes still has some challenges, namely how to make silk fibroin membrane-based electronic devices stable under normal environment, but can be automatically decomposed under given trigger conditions such as temperature, light, enzyme and solvent, and the like, which is of great significance for reducing electronic waste and promoting the development of information security and wearable equipment.

Disclosure of Invention

The invention aims to provide a transient electronic device taking a silk fibroin film as a flexible substrate and a preparation method thereof.

To this end, the invention provides a transient electronic device with a silk fibroin film as a flexible substrate, which comprises a flexible substrate and a conductive circuit;

the flexible substrate comprises a water-soluble regenerated silk fibroin film;

the conductive circuit includes silver nanowires that are transferred to the flexible substrate by casting a regenerated silk fibroin solution onto a silver nanowire pattern.

Further, the thickness of the regenerated silk fibroin membrane is 50-260 μm, preferably 90-260 μm, more preferably 90-210 μm, such as 90 μm, 100 μm, 130 μm, 160 μm, 180 μm, 210 μm.

Further, the regenerated silk fibroin is selected from one or more of regenerated mulberry silk fibroin, regenerated tussah silk fibroin, regenerated castor silk fibroin and regenerated tussah silk fibroin.

In a second aspect of the present invention, a method for preparing a transient electronic device using a silk fibroin film as a flexible substrate is provided, which comprises the following steps:

s1, casting the silver nanowire dispersion liquid on a patterned template, and forming a silver nanowire pattern on the concave part of the patterned template after the solvent is completely evaporated;

and S2, casting the regenerated silk fibroin solution on a patterned template with a silver nanowire pattern, and drying to obtain the regenerated silk fibroin film, thus obtaining the flexible transient electronic device.

Further, in step S1, the silver nanowire dispersion liquid has a mass fraction of silver nanowires of 5 to 10%, preferably 5%.

Further, in step S2, the concentration of the regenerated silk fibroin solution is 2-8% (w/v), preferably 4-6%.

Further, in step S2, the regenerated silk fibroin film has a thickness of 50 to 260 μm, preferably 90 to 260 μm, more preferably 90 to 210 μm, such as 90 μm, 100 μm, 130 μm, 160 μm, 180 μm, 210 μm.

Further, the regenerated silk fibroin is selected from one or more of regenerated mulberry silk fibroin, tussah silk fibroin, castor silk fibroin, and tussah silk fibroin.

Further, in step S1, the method for preparing the silver nanowire dispersion includes: respectively preparing a polyvinylpyrrolidone (PVP) solution and a metal chloride solution by using Ethylene Glycol (EG) as a solvent; dissolving silver nitrate in a PVP solution, mixing with a metal chloride solution, uniformly stirring, reacting at 120-150 ℃ for 4-6 h, and washing and concentrating to obtain silver nanowires; and dispersing the silver nanowires in ethanol to obtain the silver nanowire dispersion liquid.

Further, the metal chloride is sodium chloride, potassium chloride, copper chloride or ferric chloride.

Further, after washing and concentrating, the method also comprises the following steps: the residue was removed with acetone and ethanol.

Further, in step S2, the method for preparing the regenerated silk fibroin solution includes: pretreating silk with an alkali solution to obtain degummed silk fibers; dissolving the degummed silk fiber in an inorganic salt/alcohol/water ternary solvent system for dialysis; thus obtaining the regenerated silk fibroin solution.

Further, after the dialysis, the method also comprises the following steps: the dialyzed solution was centrifuged to remove impurities.

Further, the ternary solvent system of inorganic salt/alcohol/water is selected from the following ternary solvent systems: calcium chloride/ethanol/water, calcium chloride/methanol/water, calcium nitrate/methanol/water or calcium nitrate/ethanol/water; calcium chloride/ethanol/water is preferred. Preferably, the molar ratio of inorganic salt/alcohol/water is 1:2: 8.

In a specific embodiment, the alkali solution is a sodium carbonate solution; the preparation method of the regenerated silk fibroin solution comprises the following steps: pretreating silk with a sodium carbonate solution, and chopping the silk to obtain degumming silk fibers; dissolving the degummed silk fiber in a ternary solvent system of calcium chloride/ethanol/water (molar ratio is 1:2:8), dissolving at 70-80 ℃ for 3-5 h, and dialyzing for 3-3.5 d for desalination by using a dialysis bag with molecular cut-off of MWCO 3500; and centrifuging the desalted solution to obtain the regenerated silk fibroin solution.

The silk is composed of silk fibroin and sericin, wherein the silk fibroin accounts for about 75-83% of the silk. The natural silk fibroin has an antiparallel beta-folded structure, is stable in structure under the action of intermolecular and intramolecular hydrogen bonds and van der Waals force, and is insoluble in water. The silk fibroin is dissolved by an inorganic salt system and can be converted into soluble regenerated silk fibroin. Silk fibroin fibers are typically solubilized using a ternary solvent of calcium chloride, ethanol, and water, in which calcium ions can form stable complexes with hydroxyl groups on the serine and tyrosine side chains of silk fibroin, resulting in the weakening of hydrogen bonds and van der waals forces between protein chains; at the same time, ethanol may help the penetration of ions into the protein chain.

In a third aspect of the invention, the application of the transient electronic device or the preparation method in the fields of wearable equipment, biomedical sensors, implantable devices, smart clothing and medical tissue engineering is provided.

Compared with the prior art, the technical scheme of the invention has the following advantages:

(1) the transient electronic device is prepared by physically depositing silver nanowires on a patterned template and casting a regenerated silk fibroin solution on the same template, and the preparation method is simple. So that the silver nanowires are not only present on the surface of the silk film but also can be uniformly distributed over the entire pattern area of the silk film.

(2) The transient electronic device provided by the invention has high light transmittance, excellent mechanical property and excellent insulating property, and can be dissolved in water within one minute after a task is completed.

(3) The preparation method provided by the invention adopts a two-time solution casting method, and the silver nanoparticle-silk fibroin composite solution is usually prepared firstly and then formed into a film in the prior art; the method adopts a two-time solution casting method, has simple and feasible steps, low cost and good application prospect, and is expected to promote the development and application of transient electronics in the fields of information security and wearable equipment.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. In the drawings:

fig. 1 is a scanning electron microscope image of the upper surface of a regenerated silk fibroin film having a silver nanopattern;

fig. 2 is a scanning electron microscope image of the upper surface of a regenerated silk fibroin film having a silver nanopattern;

fig. 3 is a scanning electron micrograph of a cross-section of a regenerated silk fibroin film having a silver nanopattern;

FIG. 4 is an AFM image of the surface morphology of a regenerated silk fibroin film;

fig. 5 is a graph of the transmittance of regenerated silk fibroin films of different thicknesses;

fig. 6 is a stress-strain curve of regenerated silk fibroin films of different thicknesses;

FIG. 7 is a schematic diagram of an interdigital circuit; 1-finger, 2-receiving electrode, 3-driving electrode;

FIG. 8 is a graph of capacitance change of an interdigital capacitive sensor caused by a finger touch;

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The reagents and instruments used in the examples of the present invention are commercially available from conventional sources, some of which are as follows:

silk was purchased from SIMATECH;

polyvinylpyrrolidone (PVP, Mw 360000) was purchased from Sigma Aldrich.