We highlight recent acoustofluidic advances that demonstrate versatility for activities beyond periodic patterning in pressure nodes.

Precise acoustic micromanipulation is emerging as an important tool in biomedical research, where acoustic forces have the advantage of being contact‐free, label‐free, and biocompatible. Conventional acoustofluidic approaches, however, produce device‐scale effects that limit the ability to locally target acoustic energies at the microscale. In this study, we demonstrate an approach to generate designed and highly local acoustic fields using 3D resonant mass‐spring microstructures, achieving local acoustic field gradients on the order of microns, orders of magnitude smaller than the fluid wavelength. In doing so, rapid and spatially defined controllable micromanipulation, including particle capture, transport, and patterning using arbitrarily arranged micro‐resonator arrays is demonstrated. This sub‐wavelength, 3D acoustofluidic approach results in highly localized and defined micromanipulation, with potential applications across sample preparation, cell analysis, and diagnostics.

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The developed acoustofluidic device realizes microparticle and cell patterning with acoustophoretic force. It combines a planar acoustic resonator and a microstructured surface which provides complex particle formations with sub-wavelength precision.

Both the scarcity and environmental impact of disposable face masks, as in the COVID-19 pandemic, have instigated the recent development of reusable masks. Such face masks reduce transmission of infectious agents and particulates, but often impact a user's ability to be understood when materials, such as silicone or hard polymers, are used. In this work, we present a numerical optimisation approach to optimise waveguide topology, where a waveguide is used to transmit and direct sound from the interior of the mask volume to the outside air. This approach allows acoustic energy to be maximised according to specific frequency bands, including those most relevant to human speech. We employ this method to convert a resuscitator mask, made of silicone, into respiration personal protective equipment (PPE) that maximises the speech intelligibility index (SII). We validate this approach experimentally as well, showing improved SII when using the fabricated device. Together, this design represents a unique and effective approach to utilize and adapt available apparatus to filter air while improving the ability to communicate effectively, including in healthcare settings.