LMP Seminar: Acoustic surface slipping microswimmers and micro-spinners

Untethered microswimmers have significant applications in medical interventions such as targeted drug delivery and minimally invasive surgery. For the first half of the talk, I present acoustically powered microswimmers that use a fast and unidirectional locomotion strategy, termed as surface slipping, and are able to navigate on both flat and curved surfaces. These 3D-microprinted swimmers contain a trapped spherical air bubble and harness the acoustic waves for propulsion at incredibly high speeds, up to 90 body lengths per second with a body length of about 25 µm. Our proposed microswimmers have the thrust force of about two to three orders of magnitude higher than that of microorganisms, such as algae and bacteria, which is enough for navigation inside the vascular capillaries with blood flow. For the second half, I present our recently developed spinning acoustic micromachines. These micromachines consist of active-passive pairs that are capable of in-plane rotation at high speeds on solid substrates. The active parts contain a spherical bubble oscillating at high frequencies, and exploit the nonlinear inertial component in low-Reynolds fluid flow to spin around the passive blocks. Such nonconventional micromachinery designs could lay the groundwork for fast and efficient swimming in Stokes flows.