Microcage and microhand for object manipulation in microscale

Micromanipulation has been a longstanding topic of interest in the development of the science and technology. One of its important applications is in microsurgery so that doctors can utilize proper tools and perform surgery in a small space on delicate tissues of patients. Despite numerous miniature tools for simple functions in millimeter scale, the need of dexterous tools for sub-millimeter scale has not been met due to the lack of the technology. A good example to mimic is human hands.; This dissertation addresses the issue and aims to develop towards hand-like devices in microscale. We first summarize the evolution of microsurgery in medicine, leading on to the demand of more sophisticated microsurgery tools, such as micromanipulators. We then review the different technologies for such applications and describe a microcage---a passive micromanipulator based on a "trapping" mechanism that works well in a bio-liquid environment. We demonstrate this microcage formed by a radial array of bimetallic (Cr/Al) fingers curled by the residual stress mismatch between two metal layers. The strength of this microcage is also analyzed.; To provide a tool with stronger structures so that it can exert forces on sample, we design and fabricate the second generation of microcage consisting of solid segment (as opposed to flexible and curled fingers) assembled by surface tension of polymers. The assembly technique has been developed but the fact that the application of the device for real operation is limited by relatively low fabrication yield.; A microfinger device with an active capturing mechanism can apply controlled force on the objects. Inspired by muscle, the actuator from nature, we adopted the balloon actuator concept of Ritsumeikan University and miniaturized it to microscale using MEMS fabrication. The fabrication employs Parylene coating for its non-permeable film and conform coating characteristic. A microfinger device is designed, fabricated and tested successfully. It is qualitatively analyzed to obtain mechanical properties in terms of the displacement, force and effective stiffness of the microfinger through experiments.; Further analysis reveals design guidelines, leading us to achieve a fully closing microhand. The completed microhand device demonstrates the active-grasping function---holding, grabbing, and detaching small object(s) of ∼1 mm.; A dexterous micromanipulator with active-grasping capability has been long pursued in the development of micro robot and microsurgical tools. Our active microhand device, with its large force, flexible joints and robust structure, is expected to provide such capability eventually. We vision that the microhand can be integrated with microsurgical instruments to manipulate delicate cells, layers, and tissues.