Comparison of capacitive and feedback-interferometric measurements on MEMS

Abstract

In this paper, we consider a typical microelectromechanical structure consisting of a small mass suspended by four laminar springs, which can be forced to vibrate by electrical actuation, and represents the basic block of many accelerometers, gyros and resonators. Measurements of parameters, such as the actuation efficiency, the resonance frequency and the quality factor, have been performed for such device by feedback interferometry, and the results are compared with data obtained by the standard capacitive method. [622] Index Terms-Mechanical variables measurement, microsensors, microelectromechanical systems (MEMS), micromachining, optical interferometry. Valerio Annovazzi-Lodi (M'89-SM'99) was born in Novara, Italy, on November 7, 1955. He received the degree in electronic engineering from the University of Pavia, Pavia, Italy, in 1979. Since then he has been working at the Department of Electronics of the University of Pavia in the fields of electronics and electrooptics. His main research interests include injection phenomena and chaos in oscillators and lasers, electrical fiber sensors, the fiber gyroscope, passive fiber components for telecommunications and sensing, optical amplifiers, trasmission via diffused infrared radiation, micromechanical systems. In 1983, he became a Staff Researcher of the Department of Electronics of the University of Pavia, in 1992 an Associate Professor, and in 2001, a Full Professor of the same institution. He is the author of more than 80 papers and holds four patents. Dr. Annovazzi-Lodi is a member of AEI. Sabina Merlo (M'01) was born in Pavia, Italy, in 1962 and received the degree in electronic engineering from the University of Pavia in 1987. She was recipient of a Rotary Foundation Graduate Scholarship for studying at the University of Washington, Seattle. In 1989, she received the M.S.E. degree in bioengineering from the University of Washington. In 1991, she received the Ph.D. degree in electronic engineering from the University of Pavia. Since 2001, she has been Associate Professor with the Department of Electronics at the University of Pavia. Her main research interests include fiber-optic passive components and sensors, optical amplifiers, laser interferometry and microelectromechanical systems. She holds three patents and is the author of approximately 50 papers. Dr. Merlo is a member of AEI. Michele Norgia (S'98-M'00) was born in Omegna, Italy, in 1972. He received the degree in electronics engineering from the University of Pavia, Italy, in 1996 with a thesis on noise in optical amplifiers and the the Ph.D. degree in electronics engineering and computer science from the University of Pavia, working in the Optoelectronics Group. In 1997, he spent five months as a visiting student at CSELT, Torino, Italy, where he worked on fiber Bragg gratings. His main research interests are noise in optical amplifiers, interferometry and microelectromechanical sensors, and he is the author of 15 papers.

Microvalve for Fuel Cells and Miniature Gas Chromatographic System

“…The dynamic parameters of concern for the microvalve presented here are its mechanical spring constant, natural frequency, damping coefficient, closing time, settling time and actuation energy. The laser vibrometer uses an optical technique, so no physical contact is made with the valve membrane [94]. Hence there is no load applied to the valve that would alter its dynamic response; the laser vibrometer is a high-resolution measurement tool [95].…”

Analysis of vibration modes in a micromechanical square-plate resonator

“…Recently, MEMS have been characterized with scanning interferometers [2][3][4][5] as well as with feedback interferometry [6,7]. In addition, the vibration mode shapes of cantilever microbeams, micromachined membranes and microrings have been measured using an interferometric microscope with stroboscopic illumination [8,9].…”

Direct evidence of “spring softening” nonlinearity in micromachined mechanical resonator using optical beam deflection technique

“…3,4 Among micromachined mechanical systems, an important class of devices is the movable micrometer sized structures released from the substrate. 8,9 Alternatively, optical methods with the capability of accurately measuring very tiny move-ment of the movable element, such as optical beam deflection, optical interferometry, can provide much better performance by their subnanometer sensitivity and much less interference from the parasitic signals. The successful design and fabrication of these devices requires computer-aided design ͑CAD͒ simulation tools capable of accurately simulating the electromechanical performance of MEMS devices.…”