Sonolithography: In‐Air Ultrasonic Particulate and Droplet Manipulation for Multiscale Surface Patterning

Acoustic fields are increasingly being used in material handling applications for gentle, noncontact manipulation of particles in fluids. Sonolithography is based on the application of acoustic radiation forces arising from the interference of ultrasonic standing waves to direct airborne particle/droplet accumulation in defined spatial regions. This approach enables reliable and repeatable patterning of materials onto a substrate to provide spatially localized topographical or biochemical cues, structural features, or other functionalities that are relevant to biofabrication and tissue engineering applications. The technique capitalizes on inexpensive, commercially available transducers and electronics. Sonolithography is capable of rapidly patterning micrometer to millimeter scale materials onto a wide variety of substrates over a macroscale (cm2) surface area and can be used for both indirect and direct cell patterning.