Abstract
Grasping and manipulating small or micro-objects is critical for a wide range of essential biological applications, such as the assembly of small parts in microsurgery, nerve repair, and selective manipulation or separation of cells, microbes, localized cell probing, measurement etc. Different microgripping and releasing mechanisms have been reviewed and discussed in this chapter. Smart microgrippers or microcages based on the combination of highly compressively stressed diamond-like carbon (DLC) and electroplated Ni bimorph structures or SU8 polymer layer and shape memory thin films have been designed, simulated, fabricated, and characterized. Theoretical, simulation, and experimental results revealed that the radius of curvature of the bimorph layer can be adjusted by varying the DLC film stress and thickness ratio of the DLC to metal or polymer layers. The angular deflection of the bimorph structures can be adjusted by varying the finger length. The radius of curvature of the microcage is in the range of 20-100 mu m, suitable for capturing and confining micro-objects with similar sizes. The operation of this type of device is based on either (1) a large difference in thermal expansion coefficients of the DLC and the metal or polymer layers or (2) the shape memory effect. Electrical tests have shown that these microcages can be opened efficiently utilizing a power smaller than 20 mW and a frequency of 100 Hz.