June 22, 2008
June 22, 2008
June 25, 2008
13.25.1 - 13.25.7
A Computer Controlled Test System for Micro-Electro- Mechanical-Resonator (MEMS Resonator) Gas Sensors
This paper describes a computer-controlled test system designed and developed to measure and characterize the response of MEMS Resonator Gas Sensors to various gas mixtures and concentrations and temperature. The change in the resonance frequency of the MEMS resonator due to the absorbed mass of gas molecules on a thin film coating of a polymer layer is being used as a microbalance to measure hazardous gases and volatile compounds. The automated test system developed employs LabView as the software platform for interfacing, communication, data acquisition and control between a personal computer and the test setup via the GPIB bus and the USB and serial ports. The LabView program written controls the injection time of the gas to be sensed, monitors the flow rate, measures and controls the temperature of the chip and monitors and records the frequency of the electro-mechanical oscillations generated in the MEMS resonator. The development of the test system was done by a team of students as a part of their undergraduate senior design projects in electrical engineering at USM.
The project reported here comprises the design and development of a computer-controlled test system to measure and characterize the responses of MEMS-based resonant sensors to various gas mixtures, concentrations and operating temperatures in an automated way.
“MEMS” is an acronym for “Micro-Electro-Mechanical System”. These devices marry traditional mechanical systems with microelectronics using the silicon semiconductor technology and integrated circuit fabrication. MEMS technology is a natural extension of the integrated circuit technology into the electro-mechanical domain. Engineers use the technique of systematically adding thin films of material on a substrate and then selectively carving portions of those films and the substrate to form both the mechanical structures and electronic components of these devices. This type of process lends itself to the fabrication of electromechanical devices in the micrometer scale with fine features down to the sub-micrometer range. As with semiconductor chip manufacturing, this scale and technology is also conducive to the production of a large number of devices in a batch very economically. 
Gas sensors are being developed at the Microelectronics Research Labs of Electrical Engineering Department at the University of Southern Maine by employing the principles of operation of MEMS resonators. MEMS Resonators, referred to as “MEMR”s in this document, are microminiaturized electromechanical devices designed to display extremely enhanced mechanical resonance characteristics at a desired frequency. Since these devices can be miniaturized and fabricated on the same chip as an integrated circuit, they are providing an
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