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Physical Intelligence Members Publications

Acoustically-powered mobile microrobots

Overview of acoustically powered microrobots. A) Scanning electron microscope image of the 3D-printed microrobot. B) Locomotion mechanism of the robot under acoustic actuation. C) Microstreaming fluidic flow around the microrobot that causes the propulsion thrust. D) Propulsion of acoustic microrobots on curved surfaces. E) Schematics of the flexural wave-driven soft attractor walls. Wall trapping of F) polystyrene microparticles and G) microalgae swimmers under ultrasound waves.

Members

Physical Intelligence
Post-doc at ETH Zurich, Switzerland
Physical Intelligence
Ph.D Student
Physical Intelligence

Publications

Physical Intelligence Article Acoustically powered surface-slipping mobile microrobots Aghakhani, A., Yasa, O., Wrede, P., Sitti, M. Proceedings of the National Academy of Sciences, 117(7):3469-3477, 2020
Untethered synthetic microrobots have significant potential to revolutionize minimally invasive medical interventions in the future. However, their relatively slow speed and low controllability near surfaces typically are some of the barriers standing in the way of their medical applications. Here, we introduce acoustically powered microrobots with a fast, unidirectional surface-slipping locomotion on both flat and curved surfaces. The proposed three-dimensionally printed, bullet-shaped microrobot contains a spherical air bubble trapped inside its internal body cavity, where the bubble is resonated using acoustic waves. The net fluidic flow due to the bubble oscillation orients the microrobot's axisymmetric axis perpendicular to the wall and then propels it laterally at very high speeds (up to 90 body lengths per second with a body length of 25 µm) while inducing an attractive force toward the wall. To achieve unidirectional locomotion, a small fin is added to the microrobot’s cylindrical body surface, which biases the propulsion direction. For motion direction control, the microrobots are coated anisotropically with a soft magnetic nanofilm layer, allowing steering under a uniform magnetic field. Finally, surface locomotion capability of the microrobots is demonstrated inside a three-dimensional circular cross-sectional microchannel under acoustic actuation. Overall, the combination of acoustic powering and magnetic steering can be effectively utilized to actuate and navigate these microrobots in confined and hard-to-reach body location areas in a minimally invasive fashion.
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