Research On Particle Acoustic Sorting In Perturbation Inertial Flow Field

In recent years,microfluidic sorting technology has become an effective tool for cell detection and disease diagnosis.Researchers at home and abroad have applied the technology of surface acoustic wave to the research field of microfluidic and manufactured microfluidic sorting devices based on surface acoustic wave.However,the performance of acoustic sorting devices in the aspects of device design,chip cost and chip flux still need to be improved.In this paper,a high purity,low cost and high flux sorting chip design can be achieved by improving the microchannel structure,the interdigital transducer structure and the combination process of microchannel and substrate by combining active and passive technologies.This research has far-reaching significance for the design of sorting chips that can meet the needs of different application scenarios.The specific work content of this paper is as follows:(1)Design of high purity acoustic sorting chip.The passive technique uses inertial microfluidic technology to achieve aggregation of 5 μm and 10 μm particles and focusing of20 μm particles by introducing a microcolumn array into a single spiral channel.The active technology uses acoustic surface technology to achieve the sorting of 20 μm particles in the frequency range of 24.95-41.58 MHz.The optimal sorting frequency of 33.7 MHz was obtained by measuring the transverse migration distance required for 20 μm particles to complete deflection at different frequencies.At this frequency,the chip sorting purity and efficiency were92% and 100%,respectively,when the working flow rate was set to 20 μL/min.(2)Design of detachable acoustic sorting chip.Firstly,the microcolumn array structure in the straight channel was optimized to improve the sorting purity of the chip.Secondly,the detachable microchannel design is realized by adding a thin film sealing layer at the bottom of the microchannel,which makes the interdigital transducer recyclable and greatly reduces the chip cost.The reusable times of the detachable microchannel was measured to be 80 times.Finally,the sorting effect of 20 μm particles at different inclination angles is studied.When the flow rate is 20 μL/min and the inclination angle is greater than 25°,20 μm particles can be sorted from the mixture,and the chip sorting purity and efficiency reach 97% and 100%,respectively.(3)Design of high flux particle acoustic sorting chip.The single spiral microchannel is used to focus 20 μm particles and keep them away from the acoustic control angle effect region to ensure the sorting efficiency of the chip.The Y-shaped microchannel inlet was used to realize the aggregation of 5 μm particles to ensure the sorting purity of the chip.A method is proposed to increase the acoustic control area by combining a single spiral channel with a new arc-shaped interdigital transducer,and the chip flux is improved on this basis.The sorting efficiency of the chip is compared with that of the previously designed interdigital transducer at different flow rates.The coupling of single spiral channel and arc-shaped interdigital transducer is verified to improve the flux design.