On-chip mobile microrobotic transducer for high-temporal resolution sensing using dynamics analysis

Abstract Untethered mobile magnetic microrobots in liquids are under increased investigation with the intended goal to obtain in vivo transducing applications, mostly for micromanipulation or cargo transport. Using them as wireless sensors is less common though it offers a highly controllable and mobile sensing capability at micrometric scale with the capability to provide information about their dynamics and interaction with their environment. Here a system is proposed which is fully controllable by calibrated external magnetic fields and high temporal resolution (>5000 FPS ) visual feedback. With the targeted applications being in microscale fluids, a mobile magnetic microrobot is integrated into an optically transparent microfluidic chip which demonstrates sensing capabilities. In these experiments, physical sensing is quantified through microrobot dynamics analysis of its elementary planar motions (rotary and translational) and these results are related to local viscosity of fluid and friction from the interfaces. These results also allow for the characterization of swimming performances, magnetization and thus help to improve the design of the microrobotic system. An analysis of transition dynamics also provides complementary measurement on the microrobot hydrodynamics and the interaction with its substrate. The proposed on-chip mobile microrobotic system provides an advantageous testing platform to further investigate the visual servo automation control towards their in-vitro or in-vivo applications.