Dynamic Steerable Patterning of Microscale Particles and Living Cells Using an Ultrasound-Phased Array

Acoustic patterning is a noncontact method to manipulate the spatial distribution of small particles using the forces generated in an ultrasound standing wave field. The technique has found applications in fields such as cell sorting, microfabrication, and tissue engineering. For tissue engineering, acoustic patterning enables remote cell and tissue manipulation, even in clinical settings. Conventional axial patterning strategies rely on reflector-based or dual-probe approaches, limiting their application to controlled setups incompatible with in vivo conditions. In contrast, single-sided lateral patterning approaches, exploiting the transmit beamforming capabilities and tunability of a clinical ultrasound transducer array, can bridge the gap to in vivo applications. For the first time, a clinical-phased array is used to acoustically pattern microscale particles in both axial and lateral directions, with dynamic control over pattern shape and orientation by adjusting electronic transducer delays. The data are used to validate a numerical model designed to predict acoustic forces and particle displacement in current and future experiments. Finally, acoustic patterning is successfully applied to living cells, demonstrating the potential translation of the proof of concept toward living tissues. In conclusion, clinical transducer arrays can pattern particles and living cells, augmenting patterning flexibility and advancing acoustic patterning for tissue engineering.