Chemical Sensor Based on Micromechanical Systems

"We propose to develop a novel type of miniature chemical sensor utilizing very recent developments in microcantilevers. Sensors based on this technology will be up to 100 times smaller, considerably more sensitive, and less expensive than currentlyavailable chemical sensors. Microcantilevers that are 50-200 ¿m long, 10-40 ¿m wide, and 0.3-4 ¿m thick and possessing resonance frequencies in the range 10-300 kHz, have recently been used in scanning force microscopy to detect extremely small changes inforce in the range of 10-12-10-9 N. The resonance frequency and bending of the microcantilever varies reproducibly and sensitively due to adsorption of molecules on the cantilever surfaces making it an ideal chemical sensor with picogram sensitivity andparts per billion detection. Preliminary detection studies, have demonstrated detection of ppb of chemicals, Simultaneous bending measurements resulted in a sensitivity of 0.6 pg/mV. The recyclability of the chemical sensor will be demonstrated byremoving the adsorbed chemical by heating of the sensor element. We also plan to demonstrate that the sensor can be vibrated in liquid environments with a good Q-factors, allowing it to be used to detect the presence of chemicals in liquid environments.Parasitic interferences can be accounted for by using reference microcantilevers, arrays of differentially coated sensors, thermal desorption rates and/or filters. Additionally, due to the extre