Patchy Microrobots for Precise Micromanipulation

Micrororobots show promise as useful tools in applications ranging from drug delivery to micromanipulation to environmental remediation. Having the advantage of being relatively powerful, fast, and readily fabricated, spherical bubble-propelled microrobots, which are driven by the catalytic decomposition of a fuel source in their environment, are particularly well suited for many of these applications. One hurdle in using these microrobots in applications requiring precise manipulation at the microscale is the quasi-oscillatory motion of the microrobot produced by the cyclical bubble growth and burst process, as well as the interference created by the presence of the bubbles themselves. Using a simple glancing-angle deposition technique, we have fabricated novel patchy microrobots that display smoother trajectories with smaller bubble size, making them suitable for precise micromanipulation. We demonstrate the use of these microrobots by manipulating and assembling passive objects at the air-liquid interface as well as on a substrate. We also study the particle and bubble dynamics which lends insight into the process of bubble creation and dissolution, which could be useful in designing other microrobots in the future.