Recent advances and challenges of manipulation of micro- and nanoparticles by surface acoustic wave in microfluidics

As an efficient mechanical wave technology, surface acoustic wave (SAW) has shown significant potential in the field of particle manipulation in microfluidic systems in recent years. This paper systematically reviews the recent advances, key mechanisms, application fields and future challenges of SAW-driven microfluidic particle manipulation. SAW excites surface mechanical waves through a piezoelectric substrate to form a periodic pressure gradient in the microfluidic channel, and uses acoustic radiation force, viscous resistance and inertial effect to control particle motion. It has the advantages of high resolution, fast response and low power consumption. Compared with traditional manipulation technologies (such as microporous filtration and electrophoresis manipulation), SAW technology can accurately separate particles of different sizes, morphologies and densities. In recent years, the efficiency of SAW manipulation has been significantly improved by optimizing the frequency, amplitude and microfluidic channel design of acoustic waves. In terms of application, SAW technology has been successfully used in circulating tumor cell (CTCs) manipulation, rapid detection of pathogens, synthesis of nanoparticles and monitoring of water pollutants. By summarizing the mechanism and application of SAW particle manipulation, this paper provides theoretical and technical references for the high-precision, high-throughput and multifunctional development of microfluidic technology.