Acoustic trapping based on surface displacement of resonance modes

Abstract

Acoustic trapping is a promising technique for aligning particles in two-dimensional arrays, as well as for dynamic manipulation of particles individually or in groups. The actuating principles used in current systems rely on either cavity modes in enclosures or complex arrangements for phase control. Therefore, available systems either require high power inputs and costly peripheral equipment or sacrifice flexibility. This work presents a different concept for acoustic trapping of particles and cells that enables dynamically defined trapping patterns inside a simple and inexpensive setup. Here, dynamic operation and dexterous trapping are realized through the use of a modified piezoelectric transducer in direct contact with the liquid sample. Physical modeling shows how the transducer induces an acoustic force potential where the conventional trapping in the axial direction is supplemented by surface displacement dependent lateral trapping. The lateral field is a horizontal array of pronounced potential minima with frequency-dependent locations. The resulting system enables dynamic arraying of levitated trapping sites at low power and can be manufactured at ultra-low cost, operated using low-cost electronics, and assembled in less than 5 min. We demonstrate dynamic patterning of particles and biological cells and exemplify potential uses of the technique for cell-based sample preparation and cell culture.

Microfabricated acoustofluidic membrane acoustic waveguide actuator for highly localized in-droplet dynamic particle manipulation

“…technologies have brought significant contributions to the field of microfluidics for precision manipulation techniques, [1][2][3][4] notably due to their relatively low power requirement and superior biocompatibility. 5,6 Ultrasonic actuators have demonstrated the ability to accomplish various microfluidic functions such as separation, 3,[7][8][9][10][11] patterning, [12][13][14][15][16][17] trapping, [18][19][20][21] focusing, 22,23 concentrating, [24][25][26] and guiding [27][28][29] of particles and analytes, which are crucial functions for biomedical applications. To achieve such results, it is often required to enhance and confine the acoustic field near the analytes, which, at this scale, is a challenging endeavor.…”

The human neurosecretome: extracellular vesicles and particles (EVPs) of the brain for intercellular communication, therapy, and liquid-biopsy applications

“…Acoustic trapping has demonstrated high efficacy and strong enrichment performances for sample volume as low as 12.5 ul ( Bryl-Górecka et al, 2018 ; Liangsupree et al, 2021 ). Nevertheless, the set up and maintenance requires large amount of funding and the device itself are only functional when high power inputs are available ( Hammarström et al, 2021 ).…”

Introduction to the special issue on the theory and applications of acoustofluidics

“…Plazonic, et al, 14 seek to capture biological particles-Bacillus subtilis var niger as anthrax spore analogs-using acoustic waves to transport them into contact with an antibody-activated surface to aid in their detection as a biodefense sensor. Microparticles are trapped using standing wave modes in a base plate in Hammarström, et al, 15 in a glass microfluidic channel with a glycerol-coupled external piezoelectric element in Lickert, et al, 16 and on an asymmetric structure in Tahmasebipour, et al 17 Particle separation using acoustic waves is modeled in three dimensions (3D) using finite ele-ment analysis in de los Reyes, et al, 18 indicating the differences between the use of traditional bulk piezoelectric devices, 3D chip bulk piezoelectric devices, and surface acoustic wave devices. Finally, in a recent innovation, acoustic vortex beams are used in Xia, et al, 19 to manipulate particles along complex helical paths.…”