Method for optically driving micron liquid drops to rotate

Abstract

The invention discloses a method for optically driving micron liquid drops to rotate. The device used in the invention is a sandwich structure formed by two pieces of ITO glass, the ITO glass is externally connected with an alternating current power supply, a uniform electric field is generated in the middle of the sandwich layer, an a-Si: H (hydrogenated amorphous silicon) film is laid on the ITO glass at the lower layer, and the thickness of the a-Si: H (hydrogenated amorphous silicon) film is about 200 microns. According to the method, the ITO glass on which the a-Si: H thin film is laid is irradiated by utilizing focused laser irradiation to generate a non-uniform space electric field, under the action of the electric field, by adjusting the distance between the laser and the micron liquid drop, the rotating motion of the micron liquid drop can be realized, and meanwhile, the rotating speed of the liquid drop can be adjusted. In addition, the sodium chloride solute is added into the micron liquid drops, so that the power required by rotation of the liquid drops can be effectively reduced. In addition, a laser pattern with a special shape can be obtained through the spatial light modulator, so that the liquid drops rotate along the path of the laser pattern.

Description

Technical Field

[0001] The present invention relates to a technology for light-driven rotation of micron droplets. Specifically, it uses laser irradiation to irradiate ITO glass with an a-Si:H thin film, and the generated non-uniform spatial electric field interacts with the micron droplets, thereby enabling the micron droplets to rotate around the laser point, and even rotate along a complex laser pattern modulated by a spatial light modulator. Background Art

[0002] The miniaturization and automation of devices are the themes of current scientific and technological development. Therefore, the manipulation of tiny targets at the micro-nano scale has become a research hotspot and has attracted widespread attention in many fields. The motion control of small and medium-sized liquids in microsystems is of great significance and has broad application prospects in microfluidics, microrobotics, biomedicine, etc. This patent discloses a method for light-driven rotation of micron droplets. First, the rotation of micron droplets is achieved by adjusting the distance between the laser and the micron droplets. Secondly, the rotation speed of the micron droplets is controlled by adjusting the irradiation power of the laser. In addition, by changing the concentration of sodium chloride solute in the micron droplets, the power required for droplet rotation can be effectively reduced. Finally, by modulating the spatial light modulator to obtain patterned laser light, the rotational motion of micron droplets along a complex laser path can be achieved.

[0003] In 2017, Lin X et al. used a solid-state substrate composed of gold nanoparticles (AuNPs) on a glass slide to generate a temperature gradient field, enabling thermophoretic capture of biological cells. They also used a rotating linear laser to achieve photoinduced thermophoretic rotation of yeast cells using low-power light and an associated temperature gradient. However, this method requires active rotation of the linear laser and cannot achieve autonomous rotation of the manipulated target.

[0004] In 2020, X Peng et al. fabricated photothermo-electrophoretic bodies by semi-coating polystyrene (PS) beads with a thin layer of gold. Stable particle rotation was achieved through the combined effects of thermoelectric force, optical force, and Stokes drag. However, the requirements for the rotation target were stringent and required simultaneous illumination from two laser beams.

[0005] In 2024, Yan J et al. used a photovoltaic strategy to generate stable torque on microrods and nanorods on an LN / Fe substrate, achieving the rotation of the microrods. However, this method can only achieve the rotation of the microrods, and the manipulated target cannot rotate along complex patterns. Summary of the Invention

[0006] The currently reported methods for rotating micron-sized objects still face many limitations, such as: the light source power required for the rotating target is too large, and the equipment required for rotation and the method for preparing the rotating target are too complicated. In response to the above problems, the present invention provides a simple and efficient method for rotating micron droplets. This method uses the uneven spatial electric field generated by laser irradiation on ITO glass with a-Si:H film to control the rotation of micron droplets, and can even achieve the rotation of micron droplets along complex laser patterns. Moreover, by adding sodium chloride solute to the micron droplets, the power required for droplet rotation can be effectively reduced. In addition, the rotation speed of the micron droplets is controlled by laser during the entire experimental process, so this method has the characteristics of precise control and strong reliability.

[0007] A method for light-driven micron droplet rotation is described. The method comprises: using an inertial field (ITO) glass substrate coated with an a-Si:H film and transformer oil containing Span80 as an ambient medium; adding hydrated droplets to the Span80-containing transformer oil and stirring with a magnetic stirrer to obtain micron droplets uniformly distributed in the oil phase; and dropping the transformer oil containing the micron droplets onto the ITO glass substrate. The micron droplet rotation is achieved by the interaction between the spatial electric field generated by laser irradiation on the a-Si:H film-coated ITO glass substrate and the micron droplets.

[0008] The method of light-driven micron droplet rotation according to claim 1 is characterized in that the droplet rotation speed can be adjusted by varying the power of laser irradiation applied to the droplet. Furthermore, the power required for droplet rotation can be effectively reduced by adding sodium chloride solute to the micron droplet.

[0009] The method for light-driven micron droplet rotation according to claim 1 is characterized in that the motion trajectory of the droplet can be changed by changing the laser shape through a spatial light modulator, thereby achieving rotational motion along a complex pattern path.

[0010] Compared with existing technologies, the advantages of this invention are as follows: First, using an ITO glass substrate coated with an a-Si:H thin film, the rotational motion of the micronized droplets is achieved by utilizing the interaction between the non-uniform spatial electric field generated by laser irradiation and the micronized droplets. Furthermore, a spatial light modulator generates a specific laser pattern, enabling the micronized droplets to rotate along different laser patterns in a two-dimensional plane. Furthermore, by adding sodium chloride solute to the micronized droplets, the power required for droplet rotation is effectively reduced. Second, by adjusting the laser, the rotational speed of the micronized droplets can be stably controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the overall structure of the device for realizing the rotational motion of micron droplets by using ITO glass with a-Si:H thin film irradiated by focused laser as a substrate.

[0012] Figure 2 This is a process diagram of an embodiment (Example 1) of the present invention of using focused laser irradiation on ITO glass coated with a-Si:H film to achieve the rotational motion of micron droplets in a two-dimensional plane.

[0013] Figure 3 This is a process diagram of an embodiment (Example 2) of the present invention using focused laser irradiation on ITO glass coated with a-Si:H film to achieve different rotation speeds of micron droplets in a two-dimensional plane.

[0014] Figure 4 This is a process diagram of an embodiment (Example 3) of the present invention for reducing the droplet rotation power by adding sodium chloride solute to the micron droplets.

[0015] Figure 5 This is a process diagram of an embodiment (Example 4) of the present invention for achieving the movement of micron droplets along a complex pattern by irradiating ITO glass coated with an a-Si:H thin film using patterned laser light obtained through a spatial light modulator. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the embodiments and accompanying drawings. The present invention discloses a method for light-driven micron droplet rotation. The device includes: a laser 1, an electronic shutter 2, a laser beam expander 3, a spatial light modulator 4, a laser reflector 5, a focusing objective 6, an ITO sandwich structure 7, a background light source 8, a filter 9, and a CCD camera 10.

[0017] The present invention discloses a method for light-driven micron droplet rotation. The method comprises the following steps: using an indium tin oxide (ITO) glass substrate coated with an a-Si:H thin film, dropping transformer oil containing micron droplets onto the ITO glass; then using a stepper motor to adjust the objective lens position so that the incident laser is accurately focused on the ITO glass; and using a CCD camera to capture a clear image. The laser power is adjusted, and the electronic shutter is opened. The laser is reflected by a laser reflector into the focusing objective lens and focused on the ITO glass. The laser irradiation generates an uneven spatial electric field, causing the micron droplets to rotate under the influence of this spatial electric field. Using a spatial light modulator to change the laser pattern shape, the micron droplets can be rotated along a complex pattern. Furthermore, by adding sodium chloride as a solute to the micron droplets, the power required for droplet rotation can be effectively reduced. The rotation speed of the micron droplets is controlled by the laser throughout the experiment.

[0018] Taking the above into consideration, along with component costs and observation quality, the optimal ranges for various parameters are: laser 1 wavelength of 400-500nm, background light source 8 using a halogen lamp, and objective lens 6 magnification of 60x. To ensure proper light propagation and measurement accuracy, all optical components and electronic devices in the optical path are fixed to a rigid connecting frame.

[0019] The working principle of the present invention is that the inhomogeneous spatial electric field generated by laser irradiation of ITO glass coated with an a-Si:H thin film interacts with the micronized droplets. The forces acting on the micronized droplets vary depending on the laser irradiation location. Therefore, the micronized droplets can be rotated by adjusting the laser irradiation location. Furthermore, the laser pattern generated by a spatial light modulator enables the micronized droplets to rotate along complex patterns. Furthermore, the forces acting on the micronized droplets can be altered by adjusting the laser power and adding sodium chloride solute to the droplets. By varying these parameters, the droplet's rotational speed can be stably controlled.

[0020] The following is a specific embodiment of the present invention using focused laser to realize the rotation of micron droplets. The specific embodiment is only used to illustrate the present invention in detail and does not limit the scope of protection of the claims of this application.

[0021] Example 1 Using a 473nm laser with a power of 300μW, a halogen lamp as the background light source, and a focusing lens with a magnification of 60x, transformer oil containing micronized droplets with a diameter of approximately 10μm was deposited onto an ITO glass substrate coated with an a-Si:H film. A motor was used to adjust the laser irradiation position, radiating the laser around the micronized droplet, causing the droplet to rotate around the laser spot.

[0022] Example 2 Using a 473nm laser with powers of 300μW and 500μW, a halogen lamp as the background light source, and a focusing lens magnification of 60x, transformer oil containing micronized droplets with a diameter of approximately 10μm was deposited onto an ITO glass substrate coated with an a-Si:H film. The laser irradiation position was adjusted using a motor. First, a 300μW laser was used to irradiate the periphery of the micronized droplet, causing the droplet to rotate at a speed of 18.05rpm. Then, a 500μW laser was used to irradiate the periphery of the droplet, accelerating its rotation to 35.39rpm.

[0023] Example 3 Using a 473nm laser with a power of 150μW, a halogen lamp as the background light source, and a focusing lens with a magnification of 60x, a micronized droplet of transformer oil containing 20% sodium chloride was deposited onto an ITO glass substrate coated with an a-Si:H film. The droplet had a diameter of approximately 10μm. A motor was used to adjust the laser irradiation position, achieving low-power irradiation and rotation of the droplet at a speed of 17.97rpm.

[0024] Experimental Example 4 Using a 473nm laser with a power of 1000μW and a spatial light modulator to generate patterned laser light, a halogen lamp as the background light source, and a focusing lens with a magnification of 60x, transformer oil containing micronized droplets with a diameter of approximately 10μm was deposited onto an ITO glass substrate coated with an a-Si:H film. A motor was used to adjust the patterned laser irradiation position, achieving rotational motion of the micronized droplets along a complex pattern.

Claims

1. A method for light-driven micron droplet rotation, characterized by: Using an a-Si:H thin film-coated ITO glass substrate and transformer oil containing span80 as the ambient medium, hydrated droplets were added to the span80-containing transformer oil and stirred with a magnetic stirrer to obtain micronized droplets uniformly distributed in the oil phase. The transformer oil containing the micronized droplets was then dropped onto the ITO glass. The micronized droplets were rotated by the interaction between the spatial electric field generated by laser irradiation on the a-Si:H thin film-coated ITO glass and the micronized droplets.

2. The method for light-driven micron droplet rotation according to claim 1, characterized in that: By varying the power of the laser irradiating the droplets, the droplet's rotation speed can be adjusted. Furthermore, by adding sodium chloride solute to the micron droplets, the power required for droplet rotation can be effectively reduced.

3. The method for light-driven micron droplet rotation according to claim 1, characterized in that: By changing the shape of the laser through a spatial light modulator, the trajectory of the droplet can be changed, thereby achieving rotational motion along a complex pattern path.

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