MEMS Resonators for Precision Sensing

Wednesday, May 27, 2009 - 6:00 p.m. to Thursday, May 28, 2009 - 6:55 p.m.

Featuring Ashwin A. Seshia, Ph.D.
Lecturer, Department of Engineering and the Nanoscience Centre
Fellow, Queens' College
University of Cambridge

Location:  McDonnell Douglas Engineering Auditorium
Free and open to the public

Abstract:
This talk will describe ongoing research in Seshia's group in the areas of MEMS-based resonators and resonant sensors. Oscillators incorporating single crystal silicon MEMS resonators have been demonstrated with short term frequency stability of below 0.5 ppb for centre frequencies between 0.1-10 MHz and associated quality factors exceeding one million in moderate vacuum. A variety of integrated oscillator architectures have been developed for MEMS resonators. These oscillators may be viewed as timing references as well as building blocks for a variety of sensor applications. Some of these sensor applications will be discussed in detail. These applications include vibrating wire strain gauges with a resolution of close to 10 pe in a 1 Hz bandwidth and thin film monitors demonstrating sensitivities of 136 Hz/nm and a mass flux resolved noise floor of under 17 pg/cm2.  Electrometers incorporating MEMS resonators demonstrate a charge equivalent noise floor of under 6 electrons/rt-Hz.  Frequency and dimensional scaling in the presence of process and package parasitic require innovative design solutions at the transducer, device and circuit levels. Solutions to address effective electrical interfacing to small-scale mechanical structures fabricated in hybrid MEMS processes will be discussed.

About The Speaker:
Ashwin A. Seshia received a B.Tech. degree in engineering physics in 1996 from the Indian Institute of Technology Bombay, M.S. and Ph.D degrees in electrical engineering and computer sciences from the University of California, Berkeley in 1999 and 2002, respectively, and an M.A. degree from the University of Cambridge in 2008. During his time at the University of California, Berkeley, he was affiliated with the Berkeley Sensor and Actuator Center. He joined the faculty of the Engineering Department at the University of Cambridge in October 2002, where he is presently a lecturer in Micro-Electro-Mechanical Systems (MEMS), a Fellow of Queens' College, and affiliated with the Nanoscience Centre. His research interests include the design and fabrication of micro- and nano-scale sensory systems with applications to the monitoring and study of the natural and built environment. He is a member of the Institute of Electrical and Electronics Engineers (IEEE) and the American Society of Mechanical Engineers (ASME), and in 2008 was appointed Fellow of the ERA Foundation.