CN106861781B

CN106861781B - Micro-channel preparation method for reducing fluid resistance based on surface nano-bubbles

Info

Publication number: CN106861781B
Application number: CN201710229403.7A
Authority: CN
Inventors: 李大勇; 顾娟; 刘玉波; 董金波
Original assignee: Heilongjiang University of Science and Technology
Current assignee: Heilongjiang University of Science and Technology
Priority date: 2017-04-10
Filing date: 2017-04-10
Publication date: 2023-04-11
Anticipated expiration: 2037-04-10
Also published as: CN106861781A

Abstract

The invention discloses a microchannel preparation method for reducing fluid flow resistance based on surface nanobubbles. Firstly, a photoetching technology (photoetching) and an electrochemical etching technology (electrochemical etching) are adopted to obtain a microchannel with a hole-shaped microstructure on the bottom surface of a silicon surface; then, the surface of the micro-channel is silanized to ensure that the surface has better hydrophobicity; finally, glass is covered on the other side of the microchannel and sealed by using an anodic bonding technique. The micro-channel manufactured by the invention can generate nano bubbles with different protruding angles at the microporous structure by changing the pressure of the inlet and the outlet, thereby realizing the fluid drag reduction effect with different degrees and improving the transmission efficiency of microfluid.

Description

Micro-channel preparation method for reducing fluid resistance based on surface nano-bubbles

Technical Field

The invention relates to the technical field of microfluid chips, in particular to a preparation method of a microchannel for realizing microfluid slippage drag reduction based on surface nano bubbles.

Background

With the development of Micro-fluidic (Microfluidics) technology and Micro/nano-electromechanical systems (MEMS/NEMS), micro/nano-scale surface science technology becomes important. Under the micro/nano scale, the fluid channel has larger surface area to volume ratio, the influence of the surface properties of materials such as surface force, hydrophobicity and roughness on the flow of the microfluid is far larger than that of the macroscopic fluid, and the research on how to reduce the flow resistance of the fluid under the micro/nano scale also has very important theoretical significance and practical application value.

Nanobubbles (nanobubbles) are the main gas form existing on the solid-liquid interface, and typically have a spherical crown shape, a height of tens of nanometers and a contact line diameter of hundreds of nanometers, and become a hot spot problem in the interface field due to their special properties and wide potential applications. According to a model of the relationship between gas and slip length at the solid-liquid interface, the slip length is proportional to the thickness of the gas layer at the solid-liquid interface. It can be seen that the gas (nanobubbles, nanograde) at the solid-liquid interface will help to increase the slip length of the fluid and reduce the flow resistance.

At present, although a plurality of scholars research and confirm that the nano bubbles have the function of slip drag reduction, the nano bubbles are in the experimental and theoretical research stage, and no application for realizing the micro-fluid slip drag reduction based on the surface nano bubbles exists. Therefore, the preparation of the micro-fluid channel for reducing the fluid flow resistance based on the nano bubbles is a premise that the nano bubbles are applied to the aspect of sliding resistance reduction, and has very important practical significance for the development of micro/nano channel technology, micro-fluid systems and micro/nano electromechanical systems.

Disclosure of Invention

The invention aims to provide a preparation method of a micro-channel for realizing micro-fluid sliding drag reduction based on surface nano bubbles, so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme:

a method for preparing a micro-channel for realizing micro-fluid sliding drag reduction based on surface nano-bubbles is characterized by comprising the following steps.

1) And cleaning the silicon wafer (N-type 100 monocrystalline silicon) by adopting an RCA cleaning process, wherein the resistivity is 0.04-0.1V cm.

2) The main channels of the microchannels are machined on the silicon surface using photolithography (photolithography) and electrochemical etching (electrochemical etching), and then the hole-like microstructures are machined on the bottom surfaces of the channels.

3) Cleaning the surface of the micro-channel with the micro-pore structure on the bottom surface (RCA process), drying by using nitrogen, and performing silanization treatment to ensure that the surface has better hydrophobicity.

4) A glass sheet was placed over the microchannel and sealed using an anodic bonding technique.

As a further scheme of the invention: processing a main channel of the micro-channel on the surface of the silicon substrate in the step 2), and processing a hole-shaped microstructure on the bottom surface of the main channel. Main channel width W =200 μm, depth H =50 μm; the pores had a diameter of 1.6 μm and a depth of 3 μm.

As a still further scheme of the invention: and 3) performing silanization treatment on the surface of the microchannel with the microporous structure on the bottom surface by using the anhydrous toluene solution of OTS (octadeceltrichosilane), wherein the volume ratio of the anhydrous toluene solution of OTS is 1%. When the surface of the microchannel is silanized, the surface of the microchannel is immersed in an anhydrous toluene solution of Octadecyltrichlorosilane (OTS) (volume ratio: 1%) for 5 hours. After being taken out, the surface of the silanized micro-channel is ultrasonically cleaned for 3 times and 5 minutes each time by using a toluene solution, and then is ultrasonically cleaned for 5 times and 3 minutes each time by using deionized water.

The invention has the beneficial effects that: 1) The obtained bottom surface of the main channel is provided with the micropore structure, so that nano bubbles can be trapped on the micropore structure by changing the pressure of the inlet and the outlet of the microchannel, the sliding length can be increased, and the flow resistance of fluid can be reduced; 2) The surface of the whole micro-channel is silanized by OTS, so that the surface has good hydrophobicity, the sliding length of the fluid is further increased, and the flow resistance of the fluid is reduced.

Drawings

1. FIG. 1 is a schematic diagram of a microchannel preparation process based on surface nanobubble drag reduction. Wherein (a) is the main channel of the microchannel; (b) a microporous structure at the bottom of the microchannel; (c) Is a microchannel which is silanized and sealed by a glass plate.

2. FIG. 2 is a schematic diagram of a microchannel based on surface nanobubble drag reduction in a microchannel preparation process based on surface nanobubble drag reduction.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 and fig. 2, in the embodiment of the present invention, firstly, a silicon wafer is cleaned by using an RCA cleaning process, and then a main microchannel channel with a width W =200 μm and a depth H =50 μm is processed on a silicon surface by using a method of a Photolithography technique (Photolithography) and an Electrochemical etching technique (Electrochemical etching) (etching is performed on a processing surface of the silicon wafer by using an etching solution, and a bottom surface is irradiated by using long-wavelength infrared light); during processing, the adopted etching solution is Hydrofluoric acid solution (HF); then, a hole-shaped microstructure with the diameter of 1.6 mu m and the depth of 3 mu m of holes is obtained on the bottom surface of the channel by still using the same technology; subsequently, the surface of the microchannel having the microporous structure on the bottom surface was cleaned (RCA process), blown dry with nitrogen gas, and subjected to silanization treatment using an anhydrous toluene solution in a volume ratio of 1% OTS; finally, a glass sheet is placed over the microchannels and sealed using anodic bonding techniques. The method has a good etching effect, and the processed micro-channel can trap nano-bubbles on the microporous structure by changing the pressure of the inlet and the outlet of the micro-channel, so that the application of reducing the flow resistance of the fluid by using the nano-bubbles is realized.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present specification describes embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and it is to be understood that all embodiments may be combined as appropriate by one of ordinary skill in the art to form other embodiments as will be apparent to those of skill in the art from the description herein.

Claims

1. A method for preparing a micro-channel for realizing micro-fluid sliding drag reduction based on surface nano-bubbles is characterized by comprising the following steps:

1) Cleaning a silicon wafer by adopting an RCA cleaning process, wherein the silicon wafer is N-type 100 monocrystalline silicon and has the resistivity of 0.04-0.1' omega cm;

2) Processing a main channel of a micro-channel on the surface of the silicon by adopting a photoetching technology and an electrochemical etching technology, and then processing a hole-shaped microstructure on the bottom surface of the channel; etching the processing surface of the silicon wafer by using etching liquid, and irradiating the bottom surface by using long-wavelength infrared light; during processing, the adopted etching liquid is hydrofluoric acid solution; main channel width W =200 μm, depth H =50 μm; the diameter of the pores is 1.6 μm and the depth is 3 μm;

3) Cleaning the surface of the micro-channel with the micro-pore structure on the bottom surface by using an RCA process, drying by using nitrogen, and performing silanization treatment to ensure that the surface has better hydrophobicity;

carrying out silanization treatment on the surface of the microchannel with the bottom surface having the microporous structure by using an OTS anhydrous toluene solution, wherein the volume ratio of the OTS anhydrous toluene solution is 1%; when the surface of the micro-channel is subjected to silanization treatment, the surface of the micro-channel is immersed in an anhydrous toluene solution of octadecyl trichlorosilane for 5 hours; taking out the silicon-free microchannel, ultrasonically cleaning the surface of the silicon-free microchannel for 3 times and 5 minutes each time by using a toluene solution, and then ultrasonically cleaning the surface of the silicon-free microchannel for 5 times and 3 minutes each time by using deionized water;

4) A glass sheet was placed over the microchannels and sealed using an anodic bonding technique.

2. The method for preparing the microchannel for realizing the microfluidic slip drag reduction based on the surface nanobubbles according to claim 1, wherein the microchannel in the step 4) adopts an anodic bonding technology to seal a glass sheet on the other side of the microchannel.