MEMS and Robotics-based Manipulation and Characterization of Micro and Nanomaterials

by Yong Zhang

Institution: University of Toronto
Year: 2012
Keywords: MEMS; Nanomanipulation
Record ID: 1938496
Full text PDF: http://hdl.handle.net/1807/32088


Advances in the synthesis of micrometer and nanometer-sized materials have resulted in a range of novel materials having unique properties. Characterizing those materials is important for understanding their properties and exploring their applications. Physically manipulating those materials is important for constructing devices. This thesis develops tools and techniques for the manipulation and characterization of micro and nanomaterials. A microelectromechanical systems (MEMS) microgripper is developed to pick and place micro-objects, achieving high repeatability, accuracy, and speed. The adhesion forces at the microscale are overcome by actively releasing the adhered micro-object from the microgripper. A microrobotic system is built based on this microgripper and realizes automated pick-and-place of microspheres to form patterns. To characterize the electrical properties of one-dimensional nanomaterials, a nanorobotic system is developed to control four nanomanipulators for automated four-point probe measurement of individual nanowires inside a scanning electron microscope (SEM). SEM is used as a vision sensor to realize visual servo control and contact detection. To characterize the electromechanical properties of individual nanowires, a MEMS device is designed and fabricated that is capable of simultaneous tensile testing and current-voltage measurement of a nanowire specimen. A nanomanipulation procedure is developed to transfer a single nanowire from its growth substrate to the MEMS device in SEM. The piezoresistive properties of silicon nanowires are characterized. A nanomanipulation system is developed that is capable of being mounted onto and demounted from the SEM specimen stage without opening the high-vacuum chamber. The system architecture allows the nanomanipulators to be transferred through the SEM load-lock. This advance facilitates the replacement of end-effectors and circumvents chamber contamination due to venting.