Independent trapping and manipulation of microparticles using dexterous acoustic tweezers

Acoustic Tweezing and Patterning of Concentration Fields in Microfluidics

“…It has been demonstrated that transducer arrays can be used to generate acoustic vortices in fluid-filled chambers [10,[31][32][33]. By controlling the amplitude and phase of each transducer in a circular array, one can generate approximate Bessel-function pressure fields of the form [31]p…”

“…Sparked by the ambition to dynamically manipulate microparticles in solution, there have been major advances in the development of experimental methods to control ultrasound acoustic fields at the microscale [1,2]: for example, using bulk acoustic waves [3][4][5], surface acoustic waves [6][7][8][9], transducer arrays [10][11][12], and 3D-printed transmission holograms [13]. The acoustic radiation force acting on particles in acoustic fields is used in these systems to manipulate particles and cells, thereby concentrating [14], trapping [15,16], separating [17], and sorting [18] bioparticles and cells based on their acoustomechanical properties.…”

“…It is inspired by, and closely resembles, the experimental systems in Refs. [9,10,[30][31][32]. The radius of these chambers is typically around 1 mm, and the chambers may have between 8 and 64 transducer elements operating at MHz frequency.…”

“…The radius of these chambers is typically around 1 mm, and the chambers may have between 8 and 64 transducer elements operating at MHz frequency. By controlling the amplitude and phase of each transducer, approximate Bessel-function acoustic vortices may be generated by a superposition of waves, then used to trap and move microparticles [10,31].…”

A One-Sided View of Acoustic Traps

“…Standing wave schemes have recently been proposed to accurately manipulate particles in two dimensions using surface [18,19] or bulk acoustic waves [20] with phase or frequency shifts in order to demonstrate capabilities similar to OTs. However, all the aforementioned techniques share the same limitations; e.g., standing waves form multiple equilibrium positions in one or two dimensions, each of which is likely to trap one or various particles at the same time, therefore precluding separability and selectivity at the single particle level with ease [21,22].…”