Small droplet generation method based on single-hole piezoelectric diaphragm

Abstract

The invention discloses a droplet generation method based on a single-hole piezoelectric diaphragm. Under the driving circuit, the single-hole piezoelectric diaphragm generates periodic vibration, and the liquid forms a stable liquid jet flow through the micropores. The jet flow is spread in the air and impacts on the hydrophobic surface, and exists on the platform in the form of liquid drops under the action of surface tension, so that the small liquid drops are generated. By adjusting the driving voltage and the micropore diameter, the controllable and adjustable millimeter-level small liquid drops with high precision can be obtained. The method is simple in structure, small in size, capable of being miniaturized and integrated, and suitable for small droplet generation in an open type microfluid system.

Description

Technical Field

[0001] This invention patent relates to single-hole piezoelectric diaphragm technology, droplet controllable generation technology, and microfluidic control technology. Background Technology

[0002] Precise droplet generation is crucial for reliable biochemical analysis in open microfluidic systems. Currently, droplet generation in open microfluidic systems primarily employs microsyringe dripping, a method that struggles to produce millimeter-sized droplets and suffers from problems such as complex structures, demanding driving conditions, and excessively large device size. To address these issues, this invention proposes a droplet generation method based on a single-pore piezoelectric diaphragm, enabling precise and controllable generation of millimeter-sized droplets. By driving the piezoelectric diaphragm to form a stable and controllable jet, controllable generation of millimeter-sized droplets is achieved on a hydrophobic surface. Summary of the Invention

[0003] This invention patent provides a method for generating small droplets based on a single-hole piezoelectric diaphragm. A periodic electrical signal is applied to the single-hole circular piezoelectric diaphragm using a driving circuit, causing it to reciprocate. During this vibration, the volume of the microconical orifice at the center of the diaphragm changes periodically. When the metal diaphragm bends upwards, the volume of the microconical orifice increases. Due to the hysteresis of the fluid under high-frequency vibration, the pressure inside the microconical orifice decreases, and liquid flows in from the larger end of the orifice. Similarly, when the metal diaphragm bends downwards, the volume of the microconical orifice decreases, and the pressure inside the orifice increases, causing liquid to spray out from the smaller end of the orifice. This periodic process can generate a near-continuous liquid jet at the microconical orifice. By adjusting the appropriate microconical orifice size and driving voltage, the Weber number of the liquid is kept within the Rayleigh jet range, thus forming a stable jet. The liquid jet impacts a hydrophobic surface, where the liquid, under the influence of surface tension, exists as droplets, thereby achieving stable and controllable generation of millimeter-sized droplets.

[0004] The method described in this invention patent has low system complexity, small size, low cost, and is easy to miniaturize and integrate, making it suitable for the generation of millimeter-scale droplets in open microfluidic systems.

[0005] The piezoelectric diaphragm in the method described in this invention patent has a single-hole structure, with the hole located at the center of the piezoelectric diaphragm and shaped as a micro-cone.

[0006] The method described in this invention patent can adjust the droplet volume and volume growth rate as needed by adjusting the driving voltage and driving time, thereby achieving precise and efficient generation of droplet volume in the millimeter range.

[0007] The method described in this invention patent can be used to generate small droplets of various liquids, including but not limited to aqueous solutions of water and other substances.

[0008] The method described in this invention patent can improve the repeatability of droplet generation by adjusting the distance between the single-hole piezoelectric diaphragm and the hydrophobic surface.

[0009] The method described in this invention patent utilizes a driving circuit to provide square wave, sine wave, or other periodic pulse signals to drive a single-hole piezoelectric diaphragm. Attached Figure Description

[0010] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0011] Figure 1 This describes the droplet generation method mechanism implemented in this patent. Detailed Implementation

[0012] like Figure 1 The diagram illustrates the droplet generation mechanism. A periodic electrical signal is applied to a single-hole piezoelectric diaphragm 2 using a driving circuit 1, causing it to vibrate axially periodically. Liquid 3 is continuously supplied to the diaphragm 2 from its back surface. The liquid 3 passes through a micro-conical aperture 4 to form a liquid jet 5. This jet propagates in the air and impacts a hydrophobic surface 6, where surface tension generates discrete droplets 7.

Claims

1. A method for generating small droplets based on a single-pore piezoelectric diaphragm, characterized in that: A periodic electrical signal is applied to the single-hole piezoelectric diaphragm (2) by the driving circuit (1), causing the single-hole piezoelectric diaphragm (2) to vibrate and form a liquid jet (5) through the central micro-cone hole (4). Among them, the single-hole piezoelectric diaphragm (2) is composed of a circular metal diaphragm and an annular piezoelectric ceramic. The liquid jet (5) propagates in the air and impacts the hydrophobic surface (6), forming droplets (7) on the platform under the action of surface tension.

2. The method for generating small droplets based on a single-pore piezoelectric diaphragm as described in claim 1, characterized in that: The piezoelectric diaphragm has a single-pore structure, is micro-conical in shape, and is located at the center of the piezoelectric diaphragm.

3. The method for generating small droplets based on a single-pore piezoelectric diaphragm as described in claim 1, characterized in that: Under certain aperture conditions, by adjusting the driving voltage and time, the small droplets can be controllably generated within a millimeter range.

4. The method for generating small droplets based on a single-pore piezoelectric diaphragm as described in claim 1, characterized in that: It can be used to generate small droplets of a variety of liquids, including aqueous solutions of water and other substances.

5. The method for generating small droplets based on a single-pore piezoelectric diaphragm as described in claim 1, characterized in that: Adjust the distance between the single-hole piezoelectric diaphragm (2) and the hydrophobic surface (6) to improve the repeatability of droplet generation.

6. The method for generating small droplets based on a single-pore piezoelectric diaphragm as described in claim 2, characterized in that: The driving voltage is a square wave, sine wave, or other periodic pulse.

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