ResearchFields

Nanotechnology is the science of understanding and controlling matter at dimensions of 100 nanometers or less. Encompassing nanoscale science, engineering and technology, nanotechnology involves imaging, measuring, modeling and manipulating matter at this level of precision. A key goal of nanotechnology research is to create and utilize functional materials, devices and systems with novel properties and specific functionalities through the control of matter, atom by atom, molecule by molecule, or in certain applications, at the macromolecular levels. This research program involves both fundamental and applied research aimed at developing innovative nanopositioning stages and high performance controllers for ultra-fast nanoscale positioning systems with ultra-high resolutions for applications that involve imaging and manipulation at a nanoscale. The ability to control matter with sub-nanometer precision is crucial to future progress of nanotechnology. The fundamental focus in this research program is to develop new and innovative controller design methodologies to address open problems in this area. In particular, we seek to address challenging problems including: loss of positioning precision due to hysteresis, creep and scan-induced vibration in piezoelectric scanning stages, thermal drift between a probe and a surface, minimizing the effect of sensor noise in high-speed nanopositioning, and the adverse effect of cross coupling between the three axes of a nanopositioning stage.

Micro-electromechanical systems (MEMS) are commonly driven in open loop. There has been significant interest in operating MEMS transducers in closed loop to achieve higher levels of performance and robustness with respect to variations in dynamics of these systems due to, e.g. micromachining tolerances that could be as high as 20%. Unlike larger mechanical systems, where control implementation is relatively straightforward, application of feedback to a MEMS transducer could be quite complicated. Limited availability of sensor data, fast dynamics of MEMS devices and presence of sensor noise, which could be comparable to the required accuracy, makes control of MEMS a highly challenging task. The purpose of this research program is to design high-performance controllers for MEMS transducers and to implement them on prototype devices. We also design and build novel MEMS transducers for applications such as power harvesting, ultrasonic power transmission to medical implants and RF MEMS, and micron-sized nanopositioning devices.