Flexural wave-based soft attractor walls for trapping microparticles and cells

Abstract

This paper presents a flexural-wave acoustofluidic system for trapping micron-sized particles and cells at the soft wall boundaries, by exploiting resonance frequencies of a standard microscope glass slide (1 mm thick) <200 kHz.

Acoustofluidic medium exchange for preparation of electrocompetent bacteria using channel wall trapping

“…In our novel design, particles are pushed against the thin vibrating channel wall. In contrast to related work showing particle attraction to channel walls, 43,[71][72][73][74] we are able to retain cells as small as bacteria against a flow due to the constructive combination of the action of acoustic radiation force and acoustic streaming, lowering the critical particle radius. Furthermore, we demonstrated in a recent publication 73 that our novel device design can also be used in PDMS microchannels and, since the position of the thin vibrating wall can be chosen arbitrarily, our design is much more flexible than state-of-the-art methods presented in the literature, opening the door for novel applications.…”

“…Therefore, even when the particles reach the point of minimal Gor'kov potential and thus are no longer subjected to the acoustic radiation force, they will still be trapped in the acoustic streaming vortices nearby the thin wall. Our recent publication 73 and similar ones from other groups 71,72 demonstrate that a single streaming vortex close to the wall can be utilised to attract particles but is not sufficient to retain particles against a fluid flow.…”

Hemodynamics Challenges for the Navigation of Medical Microbots for the Treatment of CVDs

“… Soft attractor wall microbot. Aghakhani et al [ 36 , 37 ] developed a 3D bullet-shaped microbot containing a spherical air bubble in its internal cavity where the bubble resonates using acoustic waves. They combined the acoustic powering with magnetic steering with the purpose of effective microbot actuation and navigation in confined and hard-to-reach body locations.…”

Application of Lab-on-Chip for Detection of Microbial Nucleic Acid in Food and Environment

“…Using ultrasound to manipulate particles in microfluidics channels is a promising research direction. Aghakhani et al (2021) reported an acoustophoresis system based on flexural wave, which can capture micron-sized particles or cells on the soft wall. The acoustophoresis system is expected to play an important role in enhancing immunoassays and particle sensors.…”