WO2022134303A1

WO2022134303A1 - Device and method for optically driving liquid metal micro-droplet

Info

Publication number: WO2022134303A1
Application number: PCT/CN2021/078032
Authority: WO
Inventors: 杨浩; 蔡逸凡; 程亮; 李相鹏; 孙妍珺; 朱铭杰
Original assignee: 苏州大学
Priority date: 2020-12-24
Filing date: 2021-02-26
Publication date: 2022-06-30
Also published as: CN112717851A

Abstract

Disclosed is a device for optically driving a liquid metal micro-droplet. The device comprises a substrate, a conductive film, a photosensitive film, a container, a direct-current power supply and a driving light source, wherein the substrate, the conductive film and the photosensitive film are sequentially arranged; the container is arranged on the photosensitive film and is not in contact with the conductive film; a solution is provided in the container; a liquid metal micro-droplet is placed in the solution; and the driving light source can irradiate the photosensitive film with light. Further disclosed is a method for optically driving a liquid metal micro-droplet. According to the present invention, the liquid metal micro-droplet cannot be limited to only moving between two fixed electrodes, such that the flexibility of the movement of the liquid metal micro-droplet is greatly enhanced, and the application range of the liquid metal micro-droplet is enlarged. According to the present invention, the position of the liquid metal micro-droplet can be accurately controlled, and the device can be applied as a micro-robot, can be recycled, and is low in cost.

Description

Device and method for light-driven liquid metal microdroplets

technical field

The invention relates to the technical field of liquid metal, in particular to a device and method for driving liquid metal micro-droplets by light.

Background technique

Liquid metal usually refers to a metal that is liquid at room temperature. Common liquid metals include gallium indium tin alloy. Gallium indium tin alloy is an eutectic alloy of metal gallium, metal indium and metal tin. It is liquid at room temperature and has a strong Mobility and Adsorption. Gallium-indium-tin alloys have many excellent properties, such as high electrical and thermal conductivity, high surface tension, extremely low vapor pressure, melting point below room temperature, and most importantly, good biocompatibility, which is suitable for human body. harmless.

At present, the methods of driving liquid metal microdroplets are mainly chemical driving, electric field driving and magnetic field driving. Chemical driving is through the mixing of liquid metal and aluminum and other metals. In the solution, aluminum and the solution chemically react to generate a large number of bubbles. These bubbles will become the thrust of the droplets to drive the liquid metal, but due to the instability of the bubbles The actuation of microdroplets cannot be precisely controlled. The electric field drive can realize the directional movement of the droplet between the two fixed electrodes, but it can only move in a certain direction, and the movement position of the liquid metal droplet cannot be precisely controlled, thus greatly limiting its application range. Magnetic field drive means that the liquid metal microdroplets can be made magnetic by mixing with iron or nickel. Metal separation makes it impossible to drive liquid metal droplets for a long time.

technical solutions

In view of the deficiencies of the prior art, the purpose of the present invention is to provide a device and method for driving liquid metal microdroplets by light.

In order to achieve the above purpose, the technical solution provided by an embodiment of the present invention is as follows:

A device for driving liquid metal microdroplets by light, which is characterized in that it comprises a substrate, a conductive film, a photosensitive film, a container, a DC power supply and a driving light source, the substrate, the conductive film and the photosensitive film are arranged in sequence, and the container is arranged in the The photosensitive film is on and not in contact with the conductive film, the container is provided with a solution, the liquid metal microdroplets are placed in the solution, and the driving light source can irradiate light on the photosensitive film .

As a further improvement of the present invention, the conductive film is an indium tin oxide conductive film.

As a further improvement of the present invention, the material of the photosensitive film is oxytitanium phthalocyanine.

As a further improvement of the present invention, the substrate is boron-silicon-based substrate glass.

As a further improvement of the present invention, the container is a hollow cuboid channel.

As a further improvement of the present invention, the material of the container is polydimethylsiloxane.

As a further improvement of the present invention, the solution is sodium hydroxide solution.

As a further improvement of the present invention, the driving light source adopts a laser pointer with a wavelength of 650 nm.

A method for light-driven liquid metal microdroplets, using the device, comprising the following steps:

(1) Place the liquid metal microdroplets in a container, pour the solution into the container, and the liquid level of the solution can make the solution immerse the liquid metal microdroplets;

(2) Connect the positive and negative electrodes of the DC power supply to the conductive film and the solution respectively;

(3) Use the driving light source to illuminate the photosensitive film to generate a light spot, and the liquid metal droplet moves to the light spot.

As a further improvement of the present invention, the distance between the negative electrode of the DC power supply and the light spot is in the range of 4-10 cm.

The beneficial effects of the present invention are:

The invention can free the liquid metal micro-droplet from moving only between two fixed electrodes, greatly enhances the flexibility of the movement of the liquid metal micro-droplet, and increases its application range. The invention can precisely control the liquid metal micro-droplet. position of the droplet and apply it as a microrobot, which is recyclable and low-cost.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that are used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments described in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

1 is a schematic structural diagram of a substrate, a conductive film, and a photosensitive film according to a preferred embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a container according to a preferred embodiment of the present invention;

3 is a schematic structural diagram of a preferred embodiment of the present invention;

4 is a schematic structural diagram of a liquid metal microdroplet placed in a solution according to a preferred embodiment of the present invention;

FIG. 5 is a schematic structural diagram showing that the positive electrode and the negative electrode of the DC power supply are respectively connected to the conductive film and the solution according to the preferred embodiment of the present invention;

6 is an experimental diagram of a preferred embodiment of the present invention;

In the figure: 8. Liquid metal droplets, 10, substrate, 12, conductive film, 14, photosensitive film, 16, container, 18, DC power supply, 20, driving light source, 22, solution, 24, light spot.

Embodiments of the present invention

In order to make those skilled in the art better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described The embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The present invention can be used to optically actuate liquid metal microdroplets. Not limited to this, the present invention has application potential for more experiments based on the closed electric field driving principle.

As shown in FIG. 1-FIG. 5, a device for light-driven liquid metal microdroplets 8 includes a substrate 10, a conductive film 12, a photosensitive film 14, a container 16, a DC power supply 18 and a driving light source 20, the substrate 10, the conductive film 12. The photosensitive films 14 are arranged in sequence, the container 16 is arranged on the photosensitive film 14 and not in contact with the conductive film 12, the container 16 is provided with a solution 22, the liquid metal droplets 8 are placed in the solution 22, and the driving light source 20 can irradiate light on the photosensitive film 14 .

In the present invention, the substrate 10 is preferably a silicon boron-based substrate glass, but is not limited to a silicon-boron-based substrate glass, and can also be a silicon substrate or a mica sheet.

In the present invention, the conductive film 12 is preferably an indium tin oxide (ITO) conductive film, but is not limited to an indium tin oxide (ITO) conductive film, and can also be a gold film or a platinum film.

More preferably, the size of the conductive thin film 12 is 10 cm×10 cm.

In the present invention, the material of the photosensitive film 14 is preferably oxytitanium phthalocyanine (TiOPc), but it is not limited to oxytitanium phthalocyanine (TiOPc), and can also be hydrogenated amorphous silicon (a-Si:H) thin film or other photosensitive materials.

In the present invention, the container 16 is preferably a hollow cuboid channel. Further preferably, the inner wall size of the cuboid channel is 7cm×7cm×4cm.

Further preferably, the material of the container 16 is polydimethylsiloxane (PDMS), which is low in cost and easy to use, but is not limited to polydimethylsiloxane (PDMS), and can also be polymethyl methacrylate ( PMMA).

Further preferably, the container 16 is made by 3D printing technology.

The preferred solution 22 of the present invention is a sodium hydroxide solution, but it is not limited to a sodium hydroxide solution, and can also be a calcium hydroxide solution, or other alkaline solutions that do not react strongly with the liquid metal droplets 8.

In the present invention, the driving light source 20 preferably adopts a laser pointer with a wavelength of 650 nm to provide optical signals for driving the liquid metal microdroplets 8, but is not limited to a laser pointer with a wavelength of 650 nm, but can also be a light source with a wavelength of 650-800 nm.

The method of the present invention, a method for driving liquid metal microdroplets 8 by light, using the above-mentioned device, includes the following steps:

(1) Place the liquid metal droplets 8 in the container 16, pour the solution 22 into the container 16, and the liquid level of the solution 22 can make the solution 22 immerse the liquid metal droplets 8;

(2) Connect the positive and negative electrodes of the DC power supply 18 to the conductive film 12 and the solution 22 respectively;

(3) Using the driving light source 20 to illuminate the photosensitive film 14 to generate a light spot 24 , and the liquid metal droplet 8 moves to the light spot 24 .

As a preferred solution, the conductive film 12 and the substrate 10 form an indium tin oxide (ITO) conductive glass, which is a layer of indium tin oxide (ITO) plated on the basis of silicon boron-based substrate glass by sputtering, evaporation and other methods. Referred to as ITO) conductive film processing.

As a preferred solution, the photosensitive film 14 is prepared by the following steps:

Mix and stir with 3-5 ml of butanone and 3-5 ml of cyclohexanone, and mix and stir in equal volumes of butanone and cyclohexanone;

Add 0.9-1.5 g of oxytitanium phthalocyanine (TiOPc) powder and 0.45-0.75 g of polyvinyl butyral, mix and stir for 7-10 hours in the dark to obtain a mixed solution;

The mixed solution was spin-coated on the indium tin oxide (ITO) conductive film at 1000-1500 rpm for 20-30s, and dried and cured at 100-130 °C;

A 1 μm thick layer of oxytitanium phthalocyanine (TiOPc) was deposited on the indium tin oxide (ITO) conductive film.

As a preferred solution, the solution 22 is a sodium hydroxide solution, including 100 ml of deionized water and 2 g of sodium hydroxide.

As a preferred solution, the distance D between the negative electrode of the DC power supply 18 and the light spot 24 is in the range of 4-10 cm.

As shown in Figure 6, in order to further illustrate the method of the present invention, as a preferred solution, the following steps are included:

(1) Place the liquid metal droplet 8 in the container 16, and pour the solution 22 into the container 16. The liquid level of the solution 22 can make the solution 22 immerse the liquid metal droplet 8, as shown in Figure 6-(a) shown;

(2) Connect the positive and negative electrodes of the DC power supply 18 to the conductive film 12 and the solution 22 respectively, so that the liquid metal droplets 8 are in a conductive environment, as shown in Figure 6-(a);

(3) Using the driving light source 20 to illuminate the photosensitive film 14 to generate a light spot 24, as shown in Figure 6-(b), due to the photosensitive properties of oxytitanium phthalocyanine, the resistance at the light spot 24 drops sharply, thereby forming a closed loop , at this time, the spot 24 is equivalent to the positive electrode, and then, under the combined action of the light field and the electric field, the liquid metal droplet 8 is driven by the electrocapillary phenomenon and moves to the spot 7 . Electrocapillarity: Due to charge transfer after energization, a large number of cations accumulate near the cathode and vice versa. Therefore, a large number of cations and anions are present on the surface of the liquid metal droplets 8 near the cathode and anode, respectively. The surface of the liquid metal droplets 8 close to the cathode undergoes an oxidation reaction due to charge exchange, thereby forming a local oxide layer. On the contrary, since the anions accumulated on the surface of the liquid metal droplet 8 near the anode side and the charge of the liquid metal droplet 8 have the same polarity, which induces mutual repulsion and leads to a decrease in the interfacial tension, the liquid metal droplet 8 has the same polarity. 8 To maintain the minimum free energy of the system after energization, it increases the interfacial area with the solution. Macroscopically, this phenomenon looks like the liquid metal microdroplets 8 are stretched. If the liquid metal is small, it can move towards the anode.

Through a series of experiments, we found that when the distance D between the negative electrode of the DC power supply 18 and the light spot 24 is very close (less than 4 cm), and the voltage of the DC power supply 18 is above 5V, the liquid metal microfluid The Drop 8 is driven and responsive. As the distance between the negative electrode of the DC power supply 18 and the light spot 24 increases, driving can be achieved by increasing the voltage of the DC power supply 18, but the sensitivity will decrease. When the distance between the negative electrode of the DC power supply 18 and the light spot 24 is increased, After reaching 10 cm, the liquid metal droplet 8 will be difficult to drive.

It will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, but that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments are to be regarded in all respects as illustrative and not restrictive, and the scope of the invention is to be defined by the appended claims rather than the foregoing description, which are therefore intended to fall within the scope of the claims. All changes within the meaning and scope of the equivalents of , are included in the present invention. Any reference signs in the claims shall not be construed as limiting the involved claim.

In addition, it should be understood that although this specification is described in terms of embodiments, not each embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims

A device for driving liquid metal microdroplets by light, which is characterized in that it comprises a substrate, a conductive film, a photosensitive film, a container, a DC power supply and a driving light source, the substrate, the conductive film and the photosensitive film are arranged in sequence, and the container is arranged in the The photosensitive film is on and not in contact with the conductive film, the container is provided with a solution, the liquid metal microdroplets are placed in the solution, and the driving light source can irradiate light on the photosensitive film .
A device for light-driven liquid metal microdroplets according to claim 1, wherein the conductive film is an indium tin oxide conductive film.
The device for light-driven liquid metal microdroplets according to claim 1, wherein the material of the photosensitive film is oxytitanium phthalocyanine.
A device for light-driven liquid metal microdroplets according to claim 1, wherein the substrate is a boron-silicon-based substrate glass.
A device for light-driven liquid metal microdroplets according to claim 1, wherein the container is a hollow cuboid channel.
A device for light-driven liquid metal microdroplets according to claim 1 or 5, wherein the material of the container is polydimethylsiloxane.
A device for light-driven liquid metal microdroplets according to claim 1, wherein the solution is a sodium hydroxide solution.
The device for optically driving liquid metal microdroplets according to claim 1, wherein the driving light source adopts a laser pointer with a wavelength of 650 nm.
A method of light-driven liquid metal microdroplets, characterized in that, using the device according to any one of claims 1-8, comprising the following steps:

(1) Place the liquid metal microdroplets in a container, pour the solution into the container, and the liquid level of the solution can make the solution immerse the liquid metal microdroplets;

(2) Connect the positive and negative electrodes of the DC power supply to the conductive film and the solution respectively;

(3) Use the driving light source to illuminate the photosensitive film to generate a light spot, and the liquid metal droplet moves to the light spot.
The method for driving liquid metal microdroplets by light according to claim 9, wherein the distance between the negative electrode of the DC power supply and the light spot is in the range of 4-10 cm.