阅读说明：本技术 一种包裹液态金属的纤维及其制备方法 (Fiber wrapping liquid metal and preparation method thereof ) 是由 赵远锦 余筠如 王月桐 戴昱 于 2020-05-29 设计创作，主要内容包括：本发明涉及一种包裹液态金属纤维的制备方法,该方法基于微流控技术,首先得到具有中空结构的聚合物纤维,通过传送带及转盘收集后,以注射法将液态金属灌入纤维空腔中形成包裹液体金属的纤维。本发明制备的包裹液态金属纤维纤维外壳为聚合物,内部包裹液态金属,纤维直径为100-1000μm,长度为1cm至10m。本发明的制备方法操作简单、成本较低、实验可重复性强,所制备的纤维结构均匀,尺寸可控,具有良好的导电性,可拉伸变形,能够作为柔性电子系统中不可或缺的导电和传感原件,应用前景广阔。(The invention relates to a preparation method of a wrapped liquid metal fiber, which is based on a microfluidic technology and comprises the steps of firstly obtaining a polymer fiber with a hollow structure, collecting the polymer fiber through a conveyor belt and a rotary table, and filling liquid metal into a fiber cavity by an injection method to form the wrapped liquid metal fiber. The fiber shell wrapped with the liquid metal prepared by the invention is a polymer, the liquid metal is wrapped in the fiber shell, the diameter of the fiber is 100-1000 mu m, and the length of the fiber is 1-10 m. The preparation method provided by the invention is simple to operate, low in cost and strong in experimental repeatability, and the prepared fiber is uniform in structure, controllable in size, good in conductivity and capable of stretching and deforming, can be used as an indispensable conductive and sensing element in a flexible electronic system, and is wide in application prospect.)

1. A liquid metal coated fiber characterized by: the preparation method comprises the following steps:

(1) assembling the microfluidic chip system and the conveying device:

constructing a coaxial micro-fluidic chip comprising an inner phase channel and a continuous phase channel, a single-channel micro-fluidic chip and a conveying device, placing a collecting pool below the coaxial micro-fluidic chip, and placing a turntable below the single-channel micro-fluidic chip;

(2) preparing the fiber wrapped with the liquid metal:

respectively loading the aqueous phase solution and the continuous phase solution into an inner phase channel injector and a continuous phase solution injector of a coaxial micro-fluidic chip, connecting the inner phase solution injector with an inner phase channel inlet, and connecting the continuous phase solution injector with a continuous phase channel inlet;

pumping the aqueous phase solution and the continuous phase solution into a coaxial micro-fluidic chip by using a micro-peristaltic pump, and controlling the flow rate of each phase;

when the water phase solution and the continuous phase solution stably generate coaxial laminar flows on the coaxial microfluidic chip, the coaxial laminar flows flow flows into an external collecting pool, and the fluid is solidified by a solvent volatilization method to generate fibers;

conveying the fibers to a turntable through a conveying belt, and connecting the tail ends of the fibers with the outlet end of the single-channel microfluidic chip; and (3) loading the liquid metal into a single-channel micro-fluidic chip injector, connecting the single-channel micro-fluidic chip injector with an inlet of a single-channel micro-fluidic chip, and pumping the liquid metal into the fiber by using a micro peristaltic pump to obtain the fiber wrapped with the liquid metal.

2. A liquid metal coated fiber as claimed in claim 1, wherein: the coaxial microfluidic chip is made of silicon, glass, polymethyl methacrylate or polydimethylsiloxane microfluidic chip, and the inner diameter of the channel of the coaxial microfluidic chip is between 1 mu m and 1 mm.

3. A liquid metal coated fiber as claimed in claim 2, wherein: the single-channel microfluidic chip is formed by assembling a glass capillary and a glass sheet, and the inner diameter of the capillary ranges from 1 mu m to 1mm and is consistent with that of a channel of the coaxial microfluidic chip.

4. A liquid metal coated fiber as claimed in claim 1, wherein: the transmission device is a transmission mechanism used for transmitting fibers between the coaxial micro-fluidic chip and the single-channel micro-fluidic chip, and the transmission mechanism is formed by assembling a rotating wheel, a transmission belt on the rotating wheel and a bracket for supporting the rotating wheel.

5. A liquid metal coated fiber as claimed in claim 1, wherein: the fiber wrapping the liquid metal has a core-shell structure, wherein the shell layer is a polymer, and the core is the liquid metal.

6. A liquid metal coated fiber as claimed in claim 1, wherein: the diameter of the fiber wrapping the liquid metal is 100-1000 mu m and the length is 1 cm-10 m by adjusting the size of each channel and the flow rate of each phase solution.

7. A liquid metal coated fiber as claimed in claim 1, wherein: the inner phase solution is one or more mixed materials of deionized water, ethanol, glycol or glycerol; the continuous phase solution is polyurethane dissolved in nitrogen and nitrogen-dimethylformamide, and the mass volume ratio of the polyurethane to the solvent nitrogen and the nitrogen-dimethylformamide is 10-20%.

8. A liquid metal coated fiber as claimed in claim 1, wherein: the liquid metal is selected from one of gallium-indium alloy, gallium-indium-zinc alloy and gallium-indium-tin-zinc alloy.

9. A liquid metal coated fiber as claimed in claim 1, wherein: the solution in the collecting tank is one or more mixed materials selected from deionized water, ethanol, glycol or glycerol.

Technical Field

The invention relates to the field of conductive materials, in particular to a fiber wrapping liquid metal and a preparation method thereof

Background

Flexible electronics is an emerging electronic technology that combines electronic devices with flexible substrates. Compared with the traditional electronic system, the flexible electronic system has higher flexibility and can realize the function under different deformation states. However, the choice of materials presents challenges due to the requirement for flexible electronic systems to be soft deformable and at the same time have good electrical conductivity.

The liquid metal is a metal which is liquid at normal temperature, is amorphous and flowable, is a general name of metals or a mixture thereof with a melting point not exceeding the melting temperature of aluminum, and can be regarded as a mixture consisting of a positive ion fluid and a free electron gas. Liquid metals combine the high electrical conductivity, thermal conductivity of traditional metals with the low viscosity and fluidity of fluids, and are widely used in heat transfer agents, heat treatment agents, and flexible electronic systems.

Gallium-based alloys exhibit less toxicity than the common liquid metallic mercury and therefore are often used in place of mercury to make conductive wires, electrodes, antennas, sensors, and other novel flexible electronic devices with good electrical conductivity, deformability, and durability. However, the liquid metal has a very large surface tension and is easily oxidized in air and water to form a very thin oxide layer covering the surface, so the manipulation of the liquid metal is always a problem to be solved in the application process.

The microfluidic technology can push, mix, react and the like on the fluid on a small scale, and has the advantages of less raw material consumption, high device integration level, highly controllable fluid behavior and the like. Besides its wide application in biochemical analysis, it also plays a significant role in molecular synthesis and material preparation. In particular, in the field of fiber production, microfluidic technology has been widely used for the production of a variety of different materials, microstructured fiber materials.

Therefore, in the invention, the fiber material wrapping the liquid metal can be continuously, stably and controllably prepared by firstly preparing the outer layer fiber and secondly pouring the liquid metal into the inner part by utilizing the microfluidic technology, and the fiber material can be widely applied to flexible electronic systems.

Disclosure of Invention

In order to solve the requirement of a flexible electronic system on the deformability of a conductive material and solve the problem of difficult control of liquid metal, the invention provides a preparation method for wrapping the liquid metal in a fiber material, and the wrapped liquid metal fiber prepared by the preparation method can be applied to the flexible electronic system.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

a fiber wrapped with liquid metal is prepared by the following steps:

(1) assembling the microfluidic chip system and the conveying device:

constructing a coaxial micro-fluidic chip comprising an inner phase channel and a continuous phase channel, a single-channel micro-fluidic chip and a conveying device, placing a collecting pool below the coaxial micro-fluidic chip, and placing a turntable below the single-channel micro-fluidic chip;

(2) preparing the fiber wrapped with the liquid metal:

respectively loading the aqueous phase solution and the continuous phase solution into an inner phase channel injector and a continuous phase solution injector of a coaxial micro-fluidic chip, connecting the inner phase solution injector with an inner phase channel inlet, and connecting the continuous phase solution injector with a continuous phase channel inlet;

pumping the aqueous phase solution and the continuous phase solution into a coaxial micro-fluidic chip by using a micro-peristaltic pump, and controlling the flow rate of each phase;

when the water phase solution and the continuous phase solution stably generate coaxial laminar flows on the coaxial microfluidic chip, the coaxial laminar flows flow flows into an external collecting pool, and the fluid is solidified by a solvent volatilization method to generate fibers;

conveying the fibers to a turntable through a conveying belt, and connecting the tail ends of the fibers with the outlet end of the single-channel microfluidic chip; and (3) loading the liquid metal into a single-channel micro-fluidic chip injector, connecting the single-channel micro-fluidic chip injector with an inlet of a single-channel micro-fluidic chip, and pumping the liquid metal into the fiber by using a micro peristaltic pump to obtain the fiber wrapped with the liquid metal.

Furthermore, the coaxial microfluidic chip is made of a silicon, glass, polymethyl methacrylate or polydimethylsiloxane microfluidic chip, and the inner diameter of a channel of the coaxial microfluidic chip is between 1 mu m and 1 mm.

Furthermore, the single-channel microfluidic chip is formed by assembling a glass capillary tube and a glass sheet, and the inner diameter of the capillary tube is between 1 mu m and 1mm and is consistent with that of a channel of the coaxial microfluidic chip.

Furthermore, the transmission device is a transmission mechanism for transmitting fibers between the coaxial micro-fluidic chip and the single-channel micro-fluidic chip, and the transmission mechanism is formed by assembling a rotating wheel, a transmission belt on the rotating wheel and a bracket for supporting the rotating wheel.

Furthermore, the fiber wrapping the liquid metal has a core-shell structure, the shell layer is a polymer, and the core is the liquid metal.

Furthermore, the diameter of the fiber wrapping the liquid metal is 100-1000 μm and the length is 1 cm-10 m by adjusting the size of each channel and the flow rate of each phase solution.

Further, the inner phase solution is a mixed material of one or more than two of deionized water, ethanol, glycol or glycerol; the continuous phase solution is polyurethane dissolved in nitrogen and nitrogen-dimethylformamide, and the mass volume ratio of the polyurethane to the solvent nitrogen and the nitrogen-dimethylformamide is 10-20%.

Further, the liquid metal is selected from one of gallium-indium alloy, gallium-indium-zinc alloy and gallium-indium-tin-zinc alloy.

Further, the solution in the collecting tank is one or more mixed materials selected from deionized water, ethanol, glycol or glycerol.

Compared with the prior art, the invention has the beneficial effects that:

the invention designs, constructs and integrates different types of micro-fluidic chips by utilizing a micro-fluidic technology based on hydrodynamic action to form a micro-fluidic chip system which operates successively, and realizes the generation, collection and retreatment of fibers by utilizing an intermediate conveying device. The invention utilizes the characteristic of rapid volatilization of the polymer solvent, can realize the first preparation of the hollow fiber in the conveying and collecting processes, and simultaneously realizes the perfusion of the liquid metal by means of the controllable operation of the microfluidic chip on the liquid metal. By adjusting the flow rates of the fluids in the respective phases, liquid metal fibers of different sizes can be produced. The preparation method provided by the invention is simple to operate, low in experimental condition requirement, low in cost and strong in experimental repeatability. The fiber prepared by the invention has the advantages of uniform structure, controllable size, good electric and heat conduction characteristics, and can be widely applied to flexible electronic devices.

Drawings

FIG. 1 is a schematic diagram of an integrated system for preparing a microfluidic device for encapsulating liquid metal fibers according to the present invention.

The parts in the drawings are numbered as follows: 1-circulation pipe A, 2-circulation pipe B, 3-collection tank, 4-rotary table, 5-conveyor belt, 6-support A, 7-circulation pipe C, 8-tray, 9-support B with rotary shaft, 10-first liquid inlet power device, 11-second liquid inlet power device, 12-third liquid inlet power device, 13-fiber cavity and 14-fiber liquid metal inner core.

Detailed Description

The present invention will be described in further detail with reference to specific examples. The following examples are intended to illustrate the invention only and are not intended to limit the scope of the invention.

The fiber wrapped with the liquid metal is prepared by a microfluidic chip system, wherein the shell layer of the fiber is a polymer, and the liquid metal is wrapped inside the shell layer of the fiber; the diameter of the wrapping liquid metal fiber is 100-1000 mu m, and the length is 1 cm-10 m.

A micro-fluidic chip system for wrapping liquid metal fibers comprises a coaxial micro-fluidic chip, a conveying device and a single-channel micro-fluidic chip. The coaxial micro-fluidic chip comprises a circulation tube A, and a circulation tube B is sleeved outside the circulation tube A; the single-channel micro-fluidic chip consists of a flow tube C; the circulation pipe A is a circulation pipeline of aqueous phase solution, the circulation pipe B is a continuous phase channel, and the circulation pipe C is a liquid metal channel; the flow direction of the fluid in the flow pipe A, B, C is the same, and the flow pipe A, B, C is respectively communicated with the first liquid inlet device 10, the second liquid inlet device 11 and the third liquid inlet device 12; the liquid inlet power device comprises a micro peristaltic pump and an injector connecting needle, the micro peristaltic pump is communicated with the connecting needle of the injector through a guide pipe, and the injector connecting needle is communicated with the circulating pipe through the guide pipe; the conveying device is positioned between the two microfluidic chips and comprises a turntable 4, a conveying belt 5 and a bracket 6; the rotary table 4 is fixedly connected with the support 6, and the conveyor belt is wrapped on the periphery of the rotary table 4.

A preparation method of wrapped liquid metal fibers comprises the following steps:

(1) the preparation steps of the microfluidic chip system are as follows:

firstly, a micro-machining method is utilized, and a glass capillary, a glass sheet and a needle head are selected to establish a coaxial micro-fluidic chip and a single-channel micro-fluidic chip. The coaxial micro-fluidic chip comprises an internal phase channel and a continuous phase channel which are respectively a water phase solution channel and a polymer solution channel. The single-channel micro-fluidic chip is a liquid metal flow channel. Then, the turntable and the conveyor belt are assembled on the bracket to form the conveying device. And finally, the coaxial microfluidic chip is arranged above the collecting pool, the single-channel microfluidic chip is arranged on a tray with a rotating shaft, and the conveying device is arranged between the two microfluidic chips.

(2) The preparation steps of the fiber are as follows:

polyurethane is dissolved in nitrogen, nitrogen-dimethyl formamide with the mass volume ratio of 10-20 percent to prepare polymer solution. Respectively filling the prepared polymer solution, deionized water and liquid metal into an injector, and connecting the ports of the channels; and one or more mixed materials of deionized water, ethanol, glycol or glycerol are filled in the sub-micro-fluidic collecting pool, and the outlet end of the coaxial micro-fluidic chip is ensured to be below the collecting liquid level.

Controlling the flow rate of each phase solution by using a micro peristaltic pump, allowing the water phase solution and the continuous phase solution to form a stable coaxial flowing state, allowing the water phase solution and the continuous phase solution to flow into an external collecting tank, and solidifying the fluid by using a solvent volatilization method to form the core-shell structure polymer fiber; conveying the generated fiber terminal to the lower part of the single-channel microfluidic chip by using a conveying device, obtaining hollow polymer fibers at a tray due to volatilization of an internal solvent in the conveying process, and connecting the fiber terminal with an outlet of the single-channel microfluidic chip after a part of fibers are collected on a rotating shaft tray; and pumping the liquid metal into the fiber core by using a micro peristaltic pump to replace the cavity to form a wrapped liquid metal fiber.

The specific operation process is as follows:

(1) according to the figure 1, fixing a glass tube B on a glass sheet by using glue, then inserting the glass tube A into the glass tube B and fixing the glass tube A on the glass sheet by using glue, under the condition that the glue is not completely dried, adjusting the position between the glass tubes under a microscope to enable a pointed end outflow port of the glass tube A to be positioned in the middle of the glass tube B, finally fixing a sample application needle head at the joint of the glass tube A and the glass tube B, and filling the gap between the glass tube A and a liquid inlet of the glass tube B by using glue. And fixing the assembled device above a collecting tank, injecting collecting liquid into the collecting tank, and ensuring that the outflow port of the glass tube B is positioned below the collecting liquid level. The collection was a mixture of 40mL ethanol and 40mL deionized water.

(2) The glass tube C was fixed to the glass plate by glue as shown in FIG. 1. And fixing the assembled single-channel microfluidic chip above a tray, wherein the tray is fixed by a bracket.

(3) According to FIG. 1, the carousel, conveyor belt, and holder are assembled into a transfer device, and the transfer device is placed between two microfluidic chips.

(4) Deionized water solution is injected into the liquid inlet of the tube A through a pump 1 and a 1mL injector in the first liquid inlet power device, and polyurethane solution is injected into the tube B through a pump 2 and a 10mL injector in the second liquid inlet power device.

(5) When the mixed solution in the device flows into a collecting tank, the nitrogen-dimethyl formamide and the surrounding collecting liquid are mutually dissolved quickly to generate the core-shell structure polymer fiber.

(6) And taking out the produced fiber from the collection pool, conveying the fiber to a tray with a rotating shaft through a conveying device, and collecting the fiber, wherein in the process, the fiber core solution volatilizes to form a fiber cavity.

(7) The collected hollow fiber terminals are connected to the outlet end of a single channel microfluidic device, and the fiber ends can be tightly connected to the device outlet end due to the contraction of the fibers in air.

(8) Liquid metal is injected into the liquid inlet of the pipe C through a pump 3 and a 1mL injector in the third liquid inlet power device, flows out of the outlet of the single-channel micro-fluidic chip and enters the fiber cavity to form wrapped liquid metal fibers.

The preparation method provided by the invention is simple to operate, low in cost and strong in experimental repeatability, and the prepared fiber has the advantages of uniform structure, controllable size and good electric and heat conduction characteristics, and can be widely applied to flexible electronic devices.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention in any way, and any person skilled in the art can make any simple modification, equivalent replacement, and improvement on the above embodiment without departing from the technical spirit of the present invention, and still fall within the protection scope of the technical solution of the present invention.