阅读说明：本技术 一种基于可控润湿梯度表面的微流体控制阀 (Microfluid control valve based on controllable wetting gradient surface ) 是由 卢传民 刘悦 何津 于 2020-06-10 设计创作，主要内容包括：本发明提供了一种微流阀,包括阀体、固定于阀体内壁的柔性悬臂梁、设置于阀体上端面的挡光板和透光板、紫外灯和液滴。通过将液滴滴到柔性悬臂梁上并控制紫外灯的照射,可以使柔性悬臂梁的局部表面产生润湿梯度,并且在液滴的张力作用下,柔性悬臂梁发生一定程度的形变和位移,以此来控制阀体中微流体的流动。采用上述结构的微流阀可以使柔性悬臂梁产生可逆的形变和位移,从而可以重复地打开和闭合微流阀,降低微流阀的使用成本。(The invention provides a micro-flow valve which comprises a valve body, a flexible cantilever beam fixed on the inner wall of the valve body, a light barrier and a light transmitting plate which are arranged on the upper end surface of the valve body, an ultraviolet lamp and liquid drops. The liquid drops are dripped onto the flexible cantilever beam and the irradiation of the ultraviolet lamp is controlled, so that the local surface of the flexible cantilever beam can generate wetting gradient, and the flexible cantilever beam is deformed and displaced to a certain degree under the action of the tension of the liquid drops, so that the flow of microfluid in the valve body is controlled. The micro-flow valve adopting the structure can enable the flexible cantilever beam to generate reversible deformation and displacement, so that the micro-flow valve can be opened and closed repeatedly, and the use cost of the micro-flow valve is reduced.)

1. The utility model provides a miniflow valve, includes valve body 1, is located microfluid entry 6 and microfluid export 7 and the flexible cantilever beam 2 that one end was fixed in 1 inner wall of valve body on the terminal surface about valve body 1, its characterized in that: 1 up end of valve body is provided with barn door 3 and light-passing board 4, 4 central authorities of light-passing board open there is the drip hole 5, flexible cantilever beam 2 is by one section be on a parallel with the horizontal beam 21 of light-passing board 4, cover in the zinc oxide film 20 and one section vertical roof beam 22 of 21 up end of horizontal beam constitute, use ultraviolet lamp 8 to shine 1 up end of valve body passes through drip hole 5 to the surperficial dropwise add liquid drop 9 of zinc oxide film 20, the wettability of 20 local surfaces of zinc oxide film changes, flexible cantilever beam 2 produces deformation and displacement, thereby makes the mobile state of microfluid changes in the valve body 1.

2. The microfluidic valve of claim 1, wherein: the light barrier 3 and the light transmission plate 4 are the same in shape and size and respectively account for half of the upper end face of the valve body 1, and the light transmission plate 4 is made of transparent materials and is positioned on the left side of the upper end face of the valve body 1; the surface of the light barrier 3 is coated with light barrier material and is positioned on the right side of the upper end surface of the valve body 1.

3. The microfluidic valve of claim 1, wherein: the horizontal beam 21 and the vertical beam 22 are made of silicon nitride, the length of the horizontal beam 21 exceeds half of the length of the valve body 1, and the surface of the zinc oxide film 20 covered on the upper end surface of the horizontal beam 21 has hydrophobicity; one end of the vertical beam 22 is connected to one end of the horizontal beam 21 and extends downward to the bottom surface of the inner wall of the valve body 1.

4. The microfluidic valve of claim 1, wherein: through the irradiation of the ultraviolet lamp 8 on the upper end face of the valve body 1, the partial surface of the zinc oxide film 20 corresponding to the area under the light transmitting plate 4 is changed from hydrophobicity to hydrophilicity, and the partial surface of the zinc oxide film 20 corresponding to the area under the light barrier 3 still presents hydrophobicity.

5. The microfluidic valve of claim 1, wherein: and dripping the liquid drops 9 on the surface of the zinc oxide film 20 through the liquid dripping holes 5, wherein the liquid drops 9 automatically move and are gathered on the hydrophilic surface of the zinc oxide film 20. Under the action of the surface tension of the liquid drops 9, the horizontal beam 21 in the hydrophobic surface area of the zinc oxide film 20 is bent upwards by a certain angle to drive the vertical beam 22 to generate vertical displacement, so that the valve body 1 is in a conducting state.

6. The microfluidic valve of claim 1, wherein: and the ultraviolet lamp 8 is turned off, the horizontal beam 21 and the vertical beam 22 are restored to the initial positions, and the valve body 1 is restored to the closed state.

Technical Field

The invention relates to a microfluid control valve based on a controllable wetting gradient surface, and belongs to the field of microfluid control.

Background

In microfluidic systems, the role of a microfluidic valve is mainly to regulate the flow and direction of the microfluidic flow. Existing microfluidic valves are classified into active valves and passive valves according to the presence or absence of external excitation. Most of the methods adopted by the active valve are based on aerodynamic force, magnetic force and mechanical pressure, and the manufacturing of the micro-scale active valve relates to the manufacturing of the micro-scale, so that the technical requirement is higher; the passive valve to microfluidic regulation method is based on the change of the flow direction and pressure of the microfluid itself.

Wettability is an important property of solid surfaces. The wettability of a solid surface depends mainly on the surface free energy and the surface microstructure. Varying both the free energy and the roughness of the solid surface can alter its wettability. The contact angle of a liquid on a solid surface is often used to measure the wettability of the solid surface. Surfaces with contact angles greater than 90 ° are referred to as hydrophobic surfaces; less than 90 deg. is referred to as a hydrophilic surface. For the surface with controllable wettability, document [1] reports a zinc oxide film prepared by a sol-gel method and a low temperature liquid phase method. The surface of the film can show hydrophobicity after standing for a period of time, and the liquid contact angle can reach about 140 degrees. And after the vacuum ultraviolet irradiation, the surface can restore to the hydrophilicity. By utilizing the property of the zinc oxide film, the wetting gradient surface can be obtained by irradiating the partial surface of the zinc oxide film with vacuum ultraviolet light. And this wetting gradient can be varied back and forth.

Patent CN 102502475 a reports a micro-scale driving method and device based on surface tension. Different materials are sputtered on the surface of the base material to form a hydrophilic area and a hydrophobic area, so that liquid drops are gathered on the hydrophilic surface, and the solid-liquid contact line is limited at the boundary part of the hydrophilic area and the hydrophobic area. The surface tension of the droplet causes the micro-cantilever to be bent upward. In the patent, the wetting gradient of the surface of the matrix material is formed so as to be uncontrollable, and therefore, the reciprocating recycling is difficult to realize at a microscale.

Disclosure of Invention

The invention aims to provide a micro-fluidic valve which has a simple structure and can be recycled to reduce the manufacturing difficulty and the use cost.

In order to solve the technical problems, the invention provides a micro-fluidic valve which comprises a valve body, a micro-fluidic inlet and a micro-fluidic outlet which are positioned on the left end surface and the right end surface of the valve body, a light barrier and a light transmitting plate which are arranged on the upper end surface of the valve body, and a flexible cantilever beam fixed on the inner wall of the valve body. The center of the light-transmitting plate is provided with a dripping hole. The flexible cantilever beam is composed of a horizontal beam parallel to the light transmission plate and a vertical beam, the upper end face of the horizontal beam is further covered with a zinc oxide film, when an ultraviolet lamp is used for irradiating the upper end face of the valve body and liquid drops are dripped to the surface of the zinc oxide film through the liquid dropping holes, the wettability of the local surface of the zinc oxide film is changed, the flexible cantilever beam deforms and displaces, and therefore the flowing state of microfluid in the valve body is changed.

As an improvement of the invention, the light barrier and the light transmission plate which are arranged on the upper end surface of the valve body have the same shape and size and respectively account for half of the upper end surface of the valve body. The light transmission plate is made of transparent material and is positioned on the left side of the upper end surface of the valve body; the surface of the light barrier is coated with light blocking materials and is positioned on the right side of the upper end surface of the valve body.

As another improvement of the invention, the horizontal beam and the vertical beam are made of silicon nitride. The length of the horizontal beam exceeds half of the length of the valve body, and the surface of the zinc oxide film covered on the upper end surface of the horizontal beam has hydrophobicity; one end of the vertical beam is connected with one end of the horizontal beam and extends downwards to the bottom surface of the inner wall of the valve body.

As another improvement of the invention, the surface hydrophobicity of the zinc oxide film corresponding to the area right below the light-transmitting plate is changed into hydrophilicity by irradiating the upper end surface of the valve body by an ultraviolet lamp. And the surface of the zinc oxide film corresponding to the area under the light barrier still presents hydrophobicity.

As a further improvement of the invention, liquid drops are dripped on the surface of the zinc oxide film through the liquid dripping holes, the liquid drops automatically move and gather on the hydrophilic surface of the zinc oxide film, and under the action of the surface tension of the liquid drops, the horizontal beam in the hydrophobic surface area of the zinc oxide film is bent upwards for a certain angle to drive the vertical beam to generate vertical displacement, so that the valve body is in a conducting state.

As a further improvement of the invention, the ultraviolet lamp is turned off, the horizontal beam and the vertical beam are restored to the initial positions, and the valve body is restored to the closed state.

The invention has the following beneficial effects: by controlling the irradiation of the ultraviolet lamp, the wetting gradient of the surface of the zinc oxide film and the surface tension of liquid drops can be used repeatedly, so that the horizontal cantilever and the vertical cantilever are bent and displaced, and the micro-flow valve can be opened and closed continuously.

Drawings

FIG. 1 is a perspective view of a miniflow valve of the present invention;

FIG. 2 is a cross-sectional view of the micro flow valve of the invention in a closed state;

FIG. 3 is a diagram of a flexible cantilever member in the microfluidic valve of the present invention;

FIG. 4 is a sectional view of the miniflow valve of the present invention in a conducting state;

in the figure, the device comprises a valve body 1, a valve body 2, a flexible cantilever beam 20, a zinc oxide film 21, a horizontal beam 22, a vertical beam 3, a light barrier 4, a light transmission plate 5, a dropping liquid hole 6, a microfluid inlet 7, a microfluid outlet 8, an ultraviolet lamp 9 and liquid drops.

Detailed Description

The following describes in detail a specific embodiment of the miniflow valve of the present invention with reference to the drawings.

Fig. 1 to 4 show an embodiment of the present invention. As shown in fig. 1, a valve body 1 of the miniflow valve is a rectangular parallelepiped. The upper end face of the valve body 1 is provided with a light barrier 3 and a light transmission plate 4, and the light barrier 3 and the light transmission plate 4 are the same in shape and size and respectively account for half of the upper end face of the valve body 1. The light-transmitting plate 4 is made of transparent material, such as glass, and is located on the left side of the upper end face of the valve body 1, and a circular dropping hole 5 is formed in the center. The surface of the light barrier 3 is coated with light barrier material and is positioned on the right side of the upper end surface of the valve body 1. The ultraviolet lamp 8 is arranged right above the valve body 1, and the distance between the ultraviolet lamp 8 and the upper end face of the valve body 1 can be adjusted. As shown in fig. 2, the left and right end faces of the valve body 1 are provided with a rectangular microfluidic inlet 6 and a microfluidic outlet 7. A flexible cantilever beam 2 is fixed on the inner wall of the valve body 1, and as shown in fig. 3, the flexible cantilever beam 2 is composed of a horizontal beam 21 parallel to the light-transmitting plate, a zinc oxide film 20 covering the upper end surface of the horizontal beam 21, and a vertical beam 22. The horizontal beam 21 and the vertical beam 22 are made of silicon nitride. The length of the horizontal beam 21 exceeds half of the length of the valve body 1, and the surface of the zinc oxide film 20 covered on the upper end surface of the horizontal beam has hydrophobicity; one end of the vertical beam 22 is connected to one end of the horizontal beam 21 and extends downward to the bottom surface of the inner wall of the valve body 1.

The process of covering the zinc oxide film 20 on the upper end surface of the horizontal beam 21 can be divided into the following two steps:

(a) measuring a certain amount of ethylene glycol monomethyl ether, ethanolamine and zinc acetate, putting into a beaker, and dissolving in a water bath at 60 ℃ for 30min to form uniform and transparent sol. And then soaking the cleaned silicon nitride substrate in the sol for 1min, pulling the substrate out of the sol at a certain speed, pretreating in a 300 ℃ incubator for 10min, heating in a 600 ℃ incubator for 50min, and cooling in the air to room temperature.

(b) And using a zinc nitrate hexahydrate solution and a hexamethylenetetramine solution as reaction solutions. Uniformly stirring a certain amount of mixed solution of zinc nitrate and hexamethylenetetramine with equal molar concentration, then obliquely leaning the substrate treated in the step (a) on the inner wall of a polytetrafluoroethylene bottle filled with the solution, closing a cover to grow for 1h in a forced air drying box at the constant temperature of 150 ℃, taking out a sample, washing with deionized water, drying with nitrogen, and storing in a dark room for 24 h.

As shown in fig. 2, when the micro flow valve is required to be in a closed state, the ultraviolet lamp 8 is turned off, and at this time, the surface of the zinc oxide film 20 presents hydrophobicity, and the wetting gradient is not generated on the upper end surface of the horizontal beam 21, so that the horizontal beam 21 and the vertical beam 22 do not bend and displace. As shown in fig. 4, when the micro flow valve needs to be in a conducting state, the ultraviolet lamp 8 is turned on to irradiate the upper end surface of the valve body 1, since the light-transmitting plate 4 transmits a part of ultraviolet light, the partial surface of the zinc oxide film 20 corresponding to the region right below the light-transmitting plate 4 is changed from hydrophobic to hydrophilic, and the partial surface of the zinc oxide film 20 corresponding to the region right below the light-blocking plate 3 still presents hydrophobic, that is, a wetting gradient is generated on the surface of the zinc oxide film 20. At this time, the droplet 9, for example, water is dropped onto the surface of the zinc oxide thin film 20 through the dropping hole 5, and the droplet 9 automatically moves and is collected on the hydrophilic surface of the zinc oxide thin film 20. Under the tension of the liquid drops 9, the horizontal beam 21 in the hydrophobic surface area of the zinc oxide film 20 is bent upwards by a certain angle, and the vertical beam 22 is driven to generate vertical displacement, so that the valve body 1 is conducted. When the micro flow valve needs to be closed again, the ultraviolet lamp 8 is only needed to be closed, the surface of the zinc oxide film 20 corresponding to the area right below the light-transmitting plate 4 recovers hydrophobicity from hydrophilicity, so that the wetting gradient of the surface of the zinc oxide film 20 disappears, therefore, the horizontal beam 21 and the vertical beam 22 also recover to the initial positions, and the valve body 1 is closed.