Acoustofluidic waveguides for localized control of acoustic wavefront in microfluidics

Abstract

The precise manipulation of acoustic fields in microfluidics is of critical importance for the realization of many biomedical applications. Despite the tremendous efforts devoted to the field of acoustofluidics during recent years, dexterous control, with an arbitrary and complex acoustic wavefront, in a prescribed, microscale region is still out of reach. Here, we introduce the concept of acoustofluidic waveguide, a three-dimensional compact configuration that is capable of locally guiding acoustic waves into a fluidic environment. Through comprehensive numerical simulations, we revealed the possibility of forming complex field patterns with defined pressure nodes within a highly localized, pre-determined region inside the microfluidic chamber. We also demonstrated the tunability of the acoustic field profile through controlling the size and shape of the waveguide geometry, as well as the operational frequency of the acoustic wave. The feasibility of the waveguide concept was experimentally verified via microparticle trapping and patterning. Our acoustofluidic waveguiding structures can be readily integrated with other microfluidic configurations and can be further designed into more complex types of passive acoustofluidic devices. The waveguide platform provides a promising alternative to current acoustic manipulation techniques and is useful in many applications such as single-cell analysis, point-of-care diagnostics, and studies of cell–cell interactions.

Programmable Acoustic Metasurfaces

“…Acoustic beams, such as focused, tweezer‐like, and nonparaxial beams, are of interest for a wide range of applications including medical acoustic imaging, nondestructive evaluation, acoustic tweezers, energy harvesting, and wireless energy transfer . Although acoustic beams can be generated using conventional passive metasurfaces, those metasurfaces with fixed configurations lack maneuverability in tuning and reshaping the acoustic beams, once they are designed and fabricated.…”

Dispersion tuning and route reconfiguration of acoustic waves in valley topological phononic crystals

“…Moreover, by reducing both the lattice constant and cavity depth, miniaturized PCs could be developed for controlling ultrasonic waves. Such devices could be fabricated by advanced manufacturing techniques, such as replication-based forming [54][55][56] , high-resolution additive manufacturing [57][58][59] , and/or micromilling 60,61 . It should also be possible to reduce the response time of the system through automatic operation.…”

Acoustic fields and microfluidic patterning around embedded micro-structures subject to surface acoustic waves

“…Micropillar waveguides can also be used to effectively constrain the transducer domain for localized acoustic effects with SAW as the actuation source, where a pillar/post is used to couple acoustic energy to selected microchannel regions 48,[50][51][52] . Rambach et al demonstrated the use of this approach to create particle patterning on top of a waveguide with just a travelling wave 51 , though predictive analytical equations that describe pattern spacings have yet to be developed.…”