A device for preparing spherical liquid particles

Abstract

The invention relates to the field of new material research and development, and is a preparation device for spherical liquid particles. The device comprises a base, a hydrophobic substrate, a voltage source, a bracket, a powder tray, a camera, a metal thin rod, an injection pump, a displacement platform, an ion air gun, a vibration motor and a cable. The hydrophobic substrate is located on the base, the hydrophobic substrate is connected to the voltage source through a cable, the bracket is fixed on the base, the powder tray is connected to the bracket through a vibration motor, so that the powder tray is located above the hydrophobic substrate, the metal thin rod is located above the powder tray, the metal thin rod space is perpendicular to the powder tray, the upper end of the metal thin rod is connected to the injection pump, the injection pump is fixed under the displacement platform, the injection pump comprises a liquid chamber and a piston, the piston moves downward to transmit polar liquid to the upper end of the metal thin rod and flow to the lower end of the metal thin rod, and finally forms a droplet, the camera is located at a position of 10 cm on the positive z direction of the side of the metal thin rod, and the ion air gun is located at a position of 15 cm on the negative z direction of the side of the powder tray.

Description

Technical Field

[0001] The invention relates to the field of new material research and development, in particular to a preparation device for spherical liquid particles capable of preparing liquid droplets with a hydrophobic protective layer on the outer surface. Background Art

[0002] Droplets with a hydrophobic protective layer on the outer surface are a new material structure that has been recently developed, referred to as hydrophobic droplets, and have been applied in the fields of biotechnology, pharmaceuticals, etc. The hydrophobic layer on the surface of the hydrophobic droplets can protect the droplets from being contaminated by the external environment, especially under relatively high external pressure, so that the droplets can maintain a spherical shape. In addition, hydrophobic droplets are easier to manipulate and play an important role in certain applications. Defects of the prior art: The output of hydrophobic droplets is limited, and the sizes of the prepared droplets vary greatly. There is also the problem of contamination of the droplets during the preparation process. Moreover, the steps for preparing hydrophobic droplets with a volume below the microliter level are cumbersome and time-consuming. The device for preparing spherical liquid particles can solve the problem. Summary of the invention

[0003] In order to solve the above problems, the present invention generates sub-microliter hydrophobic droplets based on the principle of electrofluidic pulling, and vibrates the droplets deposited on the hydrophobic powder substrate to generate hydrophobic droplets of a desired size, thereby avoiding contamination of the droplets during the preparation process.

[0004] The technical solution adopted by the present invention is:

[0005] The device for preparing spherical liquid particles includes a base, a hydrophobic substrate, a voltage source, a bracket, a powder tray, a camera, a metal rod, an injection pump, a translation stage, an ion air gun, a vibration motor and a cable, wherein xyz is a three-dimensional coordinate system, the hydrophobic substrate is made of a metal sheet, the hydrophobic substrate is located on the base, the hydrophobic substrate is connected to the voltage source through a cable, the voltage range of the voltage source output is 0 to 4 kilovolts, the voltage source can form a voltage difference between the hydrophobic substrate and the metal rod, the bracket is fixed on the base, the powder tray is made of plastic, the thickness of the powder tray is 6 mm, the powder tray is connected to the bracket through a vibration motor, so that the powder tray is located above the hydrophobic substrate, the vibration motor can drive the powder tray to vibrate, the position of the powder tray can be adjusted through the bracket, and the powder tray has polytetrafluoroethylene PTFE powder The average size of polytetrafluoroethylene (PTFE) powder particles is 300 microns. The metal rod is located above the powder disk. The diameter of the metal rod is 230 microns and the length is 1.3 mm. The space of the metal rod is perpendicular to the powder disk. The upper end of the metal rod is connected to the injection pump, and the injection pump is fixed under the translation table. The translation table can make the injection pump and the metal rod move in three dimensions. The injection pump includes a cylindrical liquid chamber and a piston. The diameter of the liquid chamber of the injection pump is 4 mm. There is a polar liquid in the liquid chamber. The downward movement of the piston can transfer the polar liquid to the upper end of the metal rod and flow along the metal rod to the lower end of the metal rod to finally form droplets. The camera is located at 10 cm on the positive z direction of the side of the metal rod, and the ion air gun is located at 15 cm on the negative z direction of the side of the powder disk.

[0006] The steps of preparing hydrophobic droplets using the spherical liquid particle preparation device are as follows:

[0007] Step 1: adjust the position of the syringe pump and the thin metal rod by using the translation stage so that the lower end of the thin metal rod is located 11 cm above the hydrophobic substrate;

[0008] Step 2: Adjust the position of the powder tray by the bracket so that the powder tray is located 2 cm below the lower end of the metal rod;

[0009] Step 3: The syringe pump piston moves downward at a speed of 10 μm / s, thereby generating a droplet at the lower end of the metal rod;

[0010] Step 4: applying a DC voltage between the metal rod and the hydrophobic substrate through a voltage source, the output voltage of the voltage source increases from 0 to 3 kilovolts within 3 minutes, so as to stretch the droplet at the lower end of the metal rod to a desired volume, and finally detach from the lower end of the metal rod, and monitor the dripping process of the droplet through a camera;

[0011] Step 5: The droplets dripping from the metal rod are collected by the powder plate, and the ion airflow emitted by the ion air gun blows toward the powder plate for 20 seconds to make the charge of the droplets neutral, which is conducive to the wrapping of the hydrophobic layer.

[0012] Step 6, turning on the vibration motor to make the powder disk oscillate along the z direction, the frequency of the powder disk oscillation is 100 Hz, the amplitude of the oscillation is 600 μm, and it lasts for 50 seconds;

[0013] Step 7, turning on the vibration motor to make the powder disk oscillate along the x direction, the frequency of the powder disk oscillation is 100 Hz, the amplitude is 600 μm, and it lasts for 50 seconds;

[0014] Step eight, turn on the vibration motor to make the powder disk oscillate along the y direction. The frequency of the powder disk oscillates at 80 Hz and the amplitude is 300 μm for 30 seconds, so that the polytetrafluoroethylene (PTFE) powder is evenly wrapped on the outer surface of the droplets to form hydrophobic droplets.

[0015] The beneficial effects of the present invention are:

[0016] The device of the present invention utilizes electric field assistance and multi-directional vibration to generate sub-microliter hydrophobic droplets. The preparation process does not require manual operation, the preparation speed is fast, the pollution to the droplets is small, and the volume distribution of the obtained hydrophobic droplets is relatively uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Further explanation below in conjunction with the graphics of the present invention:

[0018] Figure 1 It is a schematic diagram of the present invention.

[0019] In the figure, 1. base, 2. hydrophobic substrate, 3. voltage source, 4. bracket, 5. powder plate, 6. camera, 7. thin metal rod, 8. injection pump, 9. translation stage, 10. ion air gun, 11. vibration motor. DETAILED DESCRIPTION

[0020] like Figure 1Schematic diagram of the present invention, including a base (1), a hydrophobic substrate (2), a voltage source (3), a bracket (4), a powder plate (5), a camera (6), a metal thin rod (7), an injection pump (8), a displacement stage (9), an ion air gun (10), a vibration motor (11) and a cable, wherein xyz is a three-dimensional coordinate system, the hydrophobic substrate (2) is made of a metal sheet, the hydrophobic substrate (2) is located on the base (1), the hydrophobic substrate (2) is connected to the voltage source (3) via a cable, and the voltage output of the voltage source (3) has a voltage range of The voltage source (3) is 0 to 4 kilovolts, and a voltage difference can be formed between the hydrophobic substrate (2) and the metal thin rod (7); the bracket (4) is fixed on the base (1); the powder plate (5) is made of plastic, and the thickness of the powder plate (5) is 6 mm. The powder plate (5) is connected to the bracket (4) through a vibration motor (11), so that the powder plate (5) is located above the hydrophobic substrate (2); the vibration motor (11) can drive the powder plate (5) to vibrate, and the position of the powder plate (5) can be adjusted through the bracket (4). The disk (5) contains polytetrafluoroethylene (PTFE) powder, the average size of the polytetrafluoroethylene (PTFE) powder particles is 300 microns, a metal thin rod (7) is located above the powder disk (5), the diameter of the metal thin rod (7) is 230 microns, and the length is 1.3 mm, the metal thin rod (7) is vertical to the powder disk (5), the upper end of the metal thin rod (7) is connected to an injection pump (8), and the injection pump (8) is fixed under a displacement platform (9), and the displacement platform (9) can make the injection pump (8) and the metal thin rod (7) Three-dimensional movement, the injection pump (8) includes a cylindrical liquid chamber and a piston. The diameter of the liquid chamber of the injection pump (8) is 4 mm. There is a polar liquid in the liquid chamber. The downward movement of the piston can transfer the polar liquid to the upper end of the metal thin rod (7), and flow along the metal thin rod (7) to the lower end of the metal thin rod (7), and finally form droplets. The camera (6) is located at a position of 10 cm on the positive z direction of the side of the metal thin rod (7), and the ion wind gun (10) is located at a position of 15 cm on the negative z direction of the side of the powder plate (5).

[0021] The device for preparing spherical liquid particles comprises a base (1), a hydrophobic substrate (2), a voltage source (3), a bracket (4), a powder disk (5), a camera (6), a metal thin rod (7), an injection pump (8), a displacement stage (9), an ion air gun (10), a vibration motor (11) and a cable, wherein xyz is a three-dimensional coordinate system, and the hydrophobic substrate (2) is made of a metal sheet; the hydrophobic substrate (2) is located on the base (1), and the hydrophobic substrate (2) is connected to the voltage source (3) via a cable, and the voltage output by the voltage source (3) ranges from 0 to 4 kilovolts, the voltage source (3) can form a voltage difference between the hydrophobic substrate (2) and the metal thin rod (7), the bracket (4) is fixed on the base (1), the powder plate (5) is made of plastic, the thickness of the powder plate (5) is 6 mm, the powder plate (5) is made of plastic, the thickness of the powder plate (5) is 6 mm, the powder plate (5) is connected to the bracket (4) through a vibration motor (11), so that the powder plate (5) is located above the hydrophobic substrate (2), the vibration motor (11) can drive the powder plate (5) to vibrate, and the powder plate (5) is connected to the bracket (4) through a vibration motor (11). ) can adjust the position of the powder disk (5), the powder disk (5) contains polytetrafluoroethylene (PTFE) powder, the average size of the polytetrafluoroethylene (PTFE) powder particles is 300 microns, the metal thin rod (7) is located above the powder disk (5), the diameter of the metal thin rod (7) is 230 microns, and the length is 1.3 mm. The metal thin rod (7) is vertical to the powder disk (5), and the upper end of the metal thin rod (7) is connected to the injection pump (8), and the injection pump (8) is fixed under the displacement platform (9). The displacement platform (9) can make the injection pump (8) ) and the thin metal rod (7) move in three dimensions, the injection pump (8) includes a cylindrical liquid chamber and a piston, the diameter of the liquid chamber of the injection pump (8) is 4 mm, and there is a polar liquid in the liquid chamber. The downward movement of the piston can transfer the polar liquid to the upper end of the thin metal rod (7), and flow along the thin metal rod (7) to the lower end of the thin metal rod (7), and finally form droplets. The camera (6) is located at a position of 10 cm on the positive z direction of the side of the thin metal rod (7), and the ion air gun (10) is located at a position of 15 cm on the negative z direction of the side of the powder plate (5).

[0022] The working principle of using voltage to make the droplet detach from the lower end of the metal thin rod (7) is as follows: a constant voltage is applied between the metal thin rod (7) and the hydrophobic substrate (2) through the voltage source (3), so that an electrostatic field is generated between the metal thin rod (7) and the hydrophobic substrate (2), and the droplet of the polar liquid is acted upon by the downward electrostatic force, and a force balance is achieved under the action of the gravity of the droplet, that is, F 重力 +F 静电力 -F 表面张力 = 0, where the gravity F 重力 =(4πr 3 / 3)ρg, r is the radius of the droplet suspended at the lower end of the metal rod (7), ρ is the liquid density, g is the gravitational acceleration, and the electrostatic force F acting on the droplet is 静电力 =ε0SE 2 / 2, ε0 is the dielectric constant of the medium between the droplet surface and the hydrophobic substrate (2), S is the surface area of ​​the droplet at the lower end of the metal rod (7), E is the electric field strength between the droplet surface and the hydrophobic substrate (2), and the surface tension F of the droplet 表面张力 =2πRγ, γ is the surface tension constant of the liquid in the droplet, R is the outer radius of the lower end of the metal rod (7), which explains F 重力 is the third-order function of the droplet radius, F 静电力 is the second-order function of the droplet radius, F 表面张力 It is a first-order function of the droplet radius, indicating that the electrostatic force has a greater influence on the surface tension of droplets with smaller sizes.

[0023] When the downward force on the droplet is greater than its surface tension, the suspended droplet will separate from the lower end of the metal rod (7). The greater the electric field strength between the metal rod (7) and the hydrophobic substrate (2), the smaller the radius when the droplet separates from the lower end of the metal rod (7). The relationship between the electric field strength at the lower end of the metal rod (7) and the size of the droplet suspended from the lower end of the metal rod (7) is expressed as It is represented by: V is the voltage applied by the voltage source (3) between the lower end of the metal rod (7) and the hydrophobic substrate (2); D is the distance between the hydrophobic substrate (2) and the lower end of the metal rod (7); and K=1.3 is the correction factor.

[0024] The powder plate (5) is located between the hydrophobic substrate (2) and the lower end of the metal thin rod (7). After the droplet separates from the lower end of the metal thin rod (7), it drips into the powder plate (5). The powder plate (5) affects the electric field distribution between the lower end of the metal thin rod (7) and the hydrophobic substrate (2), thereby changing the electrostatic force, F 静电力 =ε0S(EE / ) 2 / 2, E′ is the electric field change caused by the powder disk (5). If the electric field strength at the lower end of the metal rod (7) and the electrostatic force applied to the droplet at the lower end of the metal rod (7) only depend on the applied voltage V, then the volume of the portion of the droplet that is pulled out of the lower end of the metal rod (7) is also a function of the voltage V. Therefore, the relationship between the volume of the droplet that finally leaves the lower end of the metal rod (7) and the applied voltage V can be obtained through experimental measurement.

[0025] In addition, the volume of the droplet at the lower end of the metal rod (7) is related to the flow rate and time of the liquid in the injection pump (8). r syringe is the diameter of the liquid chamber in the syringe pump (8), is the downward speed of the injection pump (8) piston, v(t) is the volume of the droplet at the lower end of the metal rod (7). If the downward speed of the injection pump (8) piston is constant, the relationship between the volume of the droplet at the lower end of the metal rod (7) and time can be obtained.

[0026] In summary, the volume of the dripping droplet can be controlled by the voltage between the metal thin rod (7) and the hydrophobic substrate (2).

[0027] The device of the present invention uses an electric field to assist droplets to fall and deposit on a hydrophobic powder substrate, and then vibrates it in multiple directions to generate hydrophobic droplets. It can generate sub-microliter hydrophobic droplets without manual operation and can avoid contamination of the droplets.

Claims

1. A device for preparing spherical liquid particles, characterized in that: The invention utilizes electric field assistance and multi-directional vibration to generate sub-microliter hydrophobic droplets, comprising a base (1), a hydrophobic substrate (2), a voltage source (3), a bracket (4), a powder disk (5), a camera (6), a metal thin rod (7), an injection pump (8), a displacement stage (9), an ion air gun (10), a vibration motor (11) and a cable, wherein xyz is a three-dimensional coordinate system, the hydrophobic substrate (2) is made of a metal sheet, the hydrophobic substrate (2) is located on the base (1), and the hydrophobic substrate (2) is connected to the voltage source (3) via a cable. The voltage source (3) outputs a voltage in the range of 0 to 4 kilovolts. The voltage source (3) can form a voltage difference between the hydrophobic substrate (2) and the metal thin rod (7). The bracket (4) is fixed on the base (1). The powder plate (5) is made of plastic. The thickness of the powder plate (5) is 6 mm. The powder plate (5) is connected to the bracket (4) through a vibration motor (11), so that the powder plate (5) is located above the hydrophobic substrate (2). The vibration motor (11) can drive the powder plate (5) to vibrate. The powder plate can be adjusted through the bracket (4). (5), the powder disk (5) contains polytetrafluoroethylene (PTFE) powder, the average size of the polytetrafluoroethylene (PTFE) powder particles is 300 microns, the metal thin rod (7) is located above the powder disk (5), the diameter of the metal thin rod (7) is 230 microns, and the length is 1.3 mm. The metal thin rod (7) is vertical to the powder disk (5), and the upper end of the metal thin rod (7) is connected to the injection pump (8), and the injection pump (8) is fixed under the displacement platform (9). The displacement platform (9) can make the injection pump (8) and the metal thin rod (7) The thin rod (7) moves in three dimensions. The injection pump (8) includes a cylindrical liquid chamber and a piston. The diameter of the liquid chamber of the injection pump (8) is 4 mm. The liquid chamber contains a polar liquid. The downward movement of the piston can transfer the polar liquid to the upper end of the metal thin rod (7) and flow along the metal thin rod (7) to the lower end of the metal thin rod (7), eventually forming droplets. The camera (6) is located at a position of 10 cm on the positive z direction of the side of the metal thin rod (7). The ion air gun (10) is located at a position of 15 cm on the negative z direction of the side of the powder plate (5).

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