Acting on nanoparticles embedded in magnetotactic bacteria to implement propulsion and steering for microrobots

A MEMS structure based on standard CMOS process is presented. It consists in the fabrication of micro-reservoirs in which will be embedded magnetotactic bacteria (MTB) to form a propulsion system for a 550 μm × 650 μm fully autonomous micro-robot to be operated in an aqueous medium. Due to magnetotaxis inherent in each bacterium, the motility of the MTB can be exploited. Furthermore, a directional magnetic field is used to orient their swimming direction. This magnetic field is produced by micro-coils embedded in each micro-reservoir. The operational power of the microrobot is collected through four photovoltaic cells which are able to provide a current of 65 μA and a low voltage of 400 mV to drive the micro-coils. Due to the size of the microrobot, the integration of the MTB into the micro-reservoirs is a complicated task. Here, a method to facilitate the integration of the MTB into such micro-reservoirs is proposed, which consists in the use of an external magnet placed iteratively at different locations with respect to the microrobot in order to gather the MTB near the micro-reservoir aperture consequently near the magnetic field lines generated inside of the micro-coils.