Investigation Of Micro To Nanoscale Fluid Release And Microfluidic Diode

Micro-nano fluid control technology has been rapidly developed in recent decades.It provides a micro-nano laboratory system that integrates multiple functions.It has been widely used in biomedical analysis,drug delivery,environment and food testing.Application,and will gradually enter people's lives.However,as people have higher and higher requirements for micro-nano fluid control,the theory of fluid flow in the micro-nano channel needs to be further improved,and the micro-nano fluid logic control system has gradually appeared in people's vision.In this paper,based on the results obtained by the predecessors,the release process of the fluid in the micro-channel is studied in depth and the theory is improved.Based on these results,a passive microfluidic diode structure is proposed.The specific research is summarized as follows:(1)Processing and manufacturing of microfluidic device.First,a detailed review of the various manufacturing methods of microfluidic chips was made,and laser ablation technology was used to process microfluidic chips based on the standards of high efficiency,simplicity,low cost,and practicality in the experiment.After the processing plan is determined,the chip and jig are designed,manufactured and assembled in accordance with the corresponding steps on the basis of laser engraving machine processing and the principle of oxygen plasma surface bonding.Then,the size,surface characteristics,etc.of the micro-channels in the chip related to the experiment were actually measured to minimize the errors generated in the experiment.(2)Experimental test,theoretical analysis and simulation verification of microfluid release pressure.Using experimental and numerical simulation methods,the fluid release process from micrometer to nanometer rectangular channels was studied.The results of the experiment show that the release pressure of the non-wetting fluid increases with the decrease of the width of the rectangular cross-section channel and increases with the increase of the inclination angle of the channel wall.In this regard,an improved Yang-Laplace equation is established to predict the release pressure of rectangular micro/nano channels.This equation can also be applied to nanoscale channels.Both experimental and theoretical predictions have been verified by numerical simulation results.In addition,through the same experiment and simulation verification as above,we know that the wetting fluid can be released from the microchannel spontaneously when the channel wall tilt angle is less than a certain value.(3)Design and implementation of passive microfluidic diodes.Based on the understanding and application of pressure relief in the previous chapter,a passive microfluidic diode model is proposed.The fluid diode has no moving parts and utilizes an asymmetric microchannel structure,which allows water to preferentially flow in a wide pressure range in the forward direction,while the reverse flow is blocked,showing a similar effect to the electronic diode.This effect is caused by different activation pressures in all directions.In addition,the effective pressure range of the fluid diode can be flexibly adjusted by changing the channel size and wall surface characteristics.The corresponding fluid diode structure has been manufactured using the above method,and has been verified by experiments and COMSOL finite element simulation methods.This provides a novel strategy for integrated microfluidic and nanofluidic stinging flow control or logic calculation.