This paper reports an automated image-guided microrobotic tool to perform nonprehensile magnetic manipulation of large (of the order of few hundreds of microns) microscopic biological objects in the presence of an ambient fluid flow. The developed tool comprises of ferromagnetic microrobots actuated by electromagnetic coils arranged in a quadrupole configuration, a DC power source, and a pulse width modulation (PWM) based controller to vary the coil currents. In order to accomplish the stated objective of automated micromanipulation task, a two-tier approach is adopted, namely, (1) generation of a feedback planning algorithm that invokes one of the two motion maneuvers, namely, ‘arrest’ and ‘move’ and (2) development of a proportional controller that determines the currents to be passed through the coils based on the maneuver invoked so that the resultant magnetic field actuates the ferromagnetic microrobot in the desired direction. A physical experiment was conducted and reported to authenticate the validity of the developed approach. We believe that the developed tool can be used to perform automated feedback controlled micromanipulation of large biological cells and cell aggregates in the presence of an ambient fluid flow especially in in-vivo environments. The inherent biocompatibility of the microbot material provides a possibility to functionalize it with living cells and/or appropriate chemicals rendering it feasible to implement drug delivery and also perform on-chip biological experiments.

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