AVS 47th International Symposium
    MEMS Wednesday Sessions
       Session MM-WeM

Paper MM-WeM3
Chemical Detection Based on Adsorption-Induced and Photo-Induced Stresses in MEMS Devices

Wednesday, October 4, 2000, 9:00 am, Room 309

Session: Microfabricated Sensors
Presenter: I. Datskou, Environmental Engineering Group, Inc.
Authors: P.G. Datskos, Oak Ridge National Laboratory
S. Rajic, Oak Ridge National Laboratory
L.R. Senesac, Oak Ridge National Laboratory
I. Datskou, Environmental Engineering Group, Inc.
M.S. Sepaniak, University of Tennessee
C.A. Tipple, University of Tennessee
B.C. Fagan, University of Tennessee
Correspondent: Click to Email
Recently there has been an increasing demand to perform real-time in-situ chemical detection of hazardous materials, contraband chemicals, and explosive chemicals. Currently, real-time chemical detection requires rather large analytical instrumentation that are expensive and complicated to use. The advent of inexpensive mass produced MEMS (micro-electro-mechanical systems) devices opened-up new possibilities for chemical detection. For example, microstructures were found to respond to chemical stimuli by undergoing changes in their bending and resonance frequency even when a small number of molecules adsorb on their surface. In our present studies, we extended this concept by studying changes in both the adsorption-induced stress and photo-induced stress as target chemicals adsorb on the surface of microstructures. For example, microstructures that have adsorbed molecules will undergo photo-induced bending that depends on the number of absorbed molecules on the surface. However, microstructures that have undergone photo-induced bending will adsorb molecules on their surfaces in a distinctly different way. Depending on the photon wavelength and microstructure material, the microstructure can be made to bend by expanding or contracting the irradiated surface. This is important in cases where the photo-induced stresses can be used to counter any adsorption-induced stresses and increase the dynamic range. Coating the surface of the microstructure with a different material can provide chemical specificity for the target chemicals. However, by selecting appropriate photon wavelengths we can change the chemical selectivity due to the introduction of new surface states in the MEMS device. We will present and discuss our results on the use of adsorption-induced and photo-induced bending of microstructures for chemical detection.