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 10-3N/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.

This paper presents the preliminary design of a micro force sensing mobile microrobot. The design consists of a planar, vision-based micro force sensor end-effector, while the microrobot body is made from a nickel magnetic layer 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 CCD camera attached to an optical microscope. After analyzing and calibrating the stiffness of a micromachined prototype, manipulation tests are conducted to verify this microrobot prototype is indeed capable of in situ force sensing while performing a manipulation task. This concept can be scaled down further for next generation designs targeting real biomedical applications on microscale.

This paper presents a magnetic tumbling microrobot design at the micro-scale with flexible operating modes. The microrobot has a dumb-bell shape whose largest dimension is 400 μm. When subjected to an exterior predefined magnetic field, the magnetic microagent performs a tumbling motion driven by the interacting magnetic forces and momentums. By switching the magnetic field during the motion cycle the agent is also able to perform a sliding locomotion that is useful for micromanipulation. The magnetic field providing the drive force is generated by a portable coil system consisting of five electromagnetic coils. Under the available driven field, the prototype has shown adaptable mobility through tumbling mechanism on various types of surface in both dry and fluid environments, and also shown pushing manipulation in viscous fluid. This manipulation force has been experimentally evaluated through testing with AFM tip and a micro force sensor and shown to be on the order of several μNs.

Magnetic principles have proved successful for untethered submillimeter microrobotics, although challenges still exist in areas of propulsion and control. This paper presents the design, analysis, and performance results for a bimorph thin film magnetic microrobot utilizing the magnetostrictive principle as a secondary oscillating operation mode. The microrobot is no larger than 580 μm in its planar dimension and its total thickness is less than 5 μm. As a robot with magnetic material, it can be operated in a pushing/pulling mode in orthogonal directions for movement in a plane, while it's powered with an external magnetic field as low as 1 mT. For the secondary oscillating operation mode utilizing the magnetostrictive principle, in-plane strain is induced, resulting in bending and blocking forces on the robot. These forces are theoretically calculated to prove enough drive force can be generated in this mode. The design is further abstracted and translated into a piezoelectric cantilever FEM model to confirm the theorectical results. Microrobot fabrication and test-bed development based on this analysis is shown, which enabled us to participate in the final competition in the 2010 NIST Mobile Microrobot Challenge, with good performance in the dash and freestyle events. Finally, we discuss the testing results in various dry and fluid environments along with recommendations for future investigation and improvements. Keywords: microrobot, magnetostrictive, bimorph.