Selectively manipulable acoustic-powered microswimmers.

Selective actuation of a single microswimmer from within a diverse group would be a first step toward collaborative guided action by a group of swimmers. Here we describe a new class of microswimmer that accomplishes this goal. Our swimmer design overcomes the commonly-held design paradigm that microswimmers must use non-reciprocal motion to achieve propulsion; instead, the swimmer is propelled by oscillatory motion of an air bubble trapped within the swimmer's polymer body.

Continuous particle separation in a microfluidic channel via standing surface acoustic waves (SSAW).

This work introduces a method of continuous particle separation through standing surface acoustic wave (SSAW)-induced acoustophoresis in a microfluidic channel. Using this SSAW-based method, particles in a continuous laminar flow can be separated based on their volume, density and compressibility. In this work, a mixture of particles of equal density but dissimilar volumes was injected into a microchannel through two side inlets, sandwiching a deionized water sheath flow injected through a central inlet.