Sharp-edge acoustic microfluidics: Principles, structures, and applications

Polydimethylsiloxane microstructure-induced acoustic streaming for enhanced ultrasonic DNA fragmentation on a microfluidic chip

“…66 The synergistic effect of tensile stress and ultrasonic cavitation causes DNA This journal is © The Royal Society of Chemistry 2022 molecules to be stretched first and then cut by the jet formed by cavitation, leading to the observed enhancement of fragmentation performance in terms of speed and uniformity of small-size distribution. The acoustic streaming produced by sharp edges is already widely used in microfluidic applications; 58,59 Doinikov et al conducted simulations and experiments for apex angles in the range from 10°to 130°, finding that the streaming velocity is not only related to the scale of sharp edges but also decreases with the apex angle increase, 60 as was confirmed by related research. 61,62 A triangular microstructure is a standard sharp edge structure, which is expected to have the best performance in generating acoustic streaming.…”

Self-adaptive virtual microchannel for continuous enrichment and separation of nanoparticles

“…Figure S1 (C and D) shows the vortex morphologies of acoustic streaming-1 and streaming-2 under static and laminar flow, respectively. The morphology of streaming-1 is the typical state of acoustic streaming induced by sharp edges, bubbles, and high-frequency surface acoustic waves (SAWs), where the radial plane of streaming vortices ( y - z plane) is parallel with the lateral flow ( y axis) ( 39 , 41 , 47 ), while the morphology of streaming-2 is the state of acoustic streaming in our work, where the radial plane of streaming vortices ( x - z plane) is perpendicular to the lateral flow. The streaming vortex zones are represented by black dashed circles.…”

“…Combining the characteristics of acoustic waves, which do not have strict re quirements for buffer composition and good compatibility with other external fields, and the powerful handling ability of acoustic streams gives acoustofluidics unique advantages in nanoparticle manipu lation (23,24,(34)(35)(36)(37)(38). The most common strategies for generating acoustic streams include increasing the resonant frequency (39,40) and introducing a microstructure (sharp edges or bubbles) (41,42) that causes a pair of symmetrical acoustic vortices to form in the flow plane. However, this feature ensures that the effects of acoustic streaming and lateral flow are coupled on the same plane, which limits the compatibility and performance of this technology.…”

Acoustics-Actuated Microrobots

“…The rotation speed can be well adjusted by changing the acoustic field frequency or the number of rotor arms. When a sharp edge structure is acoustically excited, it oscillates and creates a pair of counter-rotating eddies around its tip ( Figure 9 B), providing an ideal tool for microfluidic operation [ 82 ]. In addition, surface acoustic wave (SAW) devices with different interdigital transducer patterns have been developed for the movement control of small particles [ 83 ], precise shunting of microfluidics [ 84 , 85 , 86 ], and positioning of droplets applications [ 87 ].…”