A Microforce-Sensing Mobile Microrobot for Automated Micromanipulation Tasks

This paper presents a microforce-sensing mobile microrobot (μFSMM) for use in automated micromanipulation tasks. The design consists of a planar vision-based microforce sensor end-effector, while the microrobot body is made of chemically etched nickel that is driven by an exterior magnetic field. With a known stiffness, the manipulation forces can be determined from observing the deformation of the end-effector through a camera attached to an optical microscope. After analyzing and calibrating the stiffness of a micromachined prototype, the mobility and in situ force-sensing capabilities are verified through real-time, closed loop, force controlled manipulation tests with automated path planning and navigation. The calibrated stiffness of the microforce sensor end-effectors fabricated is on the order of 10 -3 N/m. The online (real time) force-sensing resolution is approximately 1.5 μN. The sensing range is 0-20 μN along the two planar directions. In automated micromanipulation experiments with a microcomponent, the μFSMM utilizes realtime force control to apply a prescribed force of 6 μN to a desired location on a fixed microobject. Similarly, in another automated micromanipulation experiment, the μFSMM demonstrates the use of real-time force control to limit the manipulation forces experienced by the microobject to remain below a threshold of 12 μN.