Realization of nanoscale resolution with a micromachined thermally actuated testing stage

The design, fabrication, and characterization of a microelectromechanical systems (MEMS) stress–strain device for testing the mechanical properties of nanomaterials is presented. Thermal actuation, with integrated motion amplification structures, was used to both minimize the operating temperature of the device as well as realize fine motion control over large displacements. The device has a working range from tens of nanometers up to 10 micrometers. Displacements as small as 30 nm per 10 mA input dc current increments were obtained for the first time with thermal actuators micromachined by deep reactive ion etching (DRIE). The height difference (offset) between the moving and fixed platforms was less than 40 nm over the entire working range of the device for the input power range studied. A 0.27 μN force is predicted for an actuator displacement of 30 nm based on mechanical models of the device; the calculated force increases linearly up to 88 μN for the maximum 9.7 μm displacement. The operating characteristics obtained for this initial design suggest that this methodology will be useful in producing a variety of MEMS stress–strain stages custom designed to yield the force and displacement resolution necessary to test many nanomaterials and nanostructures.