A Novel MEMS-based Nanoscale Material Testing System

We have developed and tested the world’s smallest material testing system for the in situ mechanical testing of nanostructures in scanning and transmission electron microscopy (SEM and TEM). The testing system consists of an actuator and a load sensor fabricated by means of surface micromachining. The specimen can be either cofabricated or mounted to the testing platform by other external means. Two types of actuators are implemented: thermal actuator for displacement control and comb drive actuator for force control. The load sensor is based on differential capacitance measurement, from which load history of the specimen is recorded. We demonstrated the system capabilities by testing free-standing polysilicon films and metallic nanowires. This is the first nanoscale material testing system, which makes possible continuous observation of the specimen deformation and failure with sub-nanometer resolution, while simultaneously measuring the applied load electronically with nano-Newton resolution. It provides a powerful tool for nanomechanical characterization of materials. In addition, it represents a milestone within the path anticipated by Richard Feynman in his talk “There is Plenty of Room at the Bottom ” [1]. In fact the entire system can be placed on the head of a pin with dimensions of one sixteenth of an inch across. 1