AVS 46th International Symposium
    The Science of Micro-Electro-Mechanical Systems Topical Conference Wednesday Sessions
       Session MM-WeA

Paper MM-WeA8
Selective Organophosphonate Chemical Sensors Using Self-Assembled Composite Monolayers and Adsorption-Induced Stresses in MEMS Devices

Wednesday, October 27, 1999, 4:20 pm, Room 620

Session: Micro-Science and Tribology
Presenter: H.M. Meyer, Oak Ridge National Laboratory
Authors: P.G. Datskos, Oak Ridge National Laboratory
H.M. Meyer, Oak Ridge National Laboratory
D. Karst, Virginia Tech
M.J. Sepaniak, 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 opens-up new possibilities for chemical detection. For example, microcantilevers 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. We describe a novel organophosphonate chemical sensor that is based on adsorption-induced stresses in MEMS (micro-electro-mechanical systems) and self-assembled monolayers. The MEMS microcantilever chemical sensor was found to exhibit high sensitivity, reversibility and chemical selectivity. Target molecules adsorbed on the surface of a microcantilever induce a differential surface stress causing changes in both the resonance frequency of the microcantilever and its bending. Measurable changes in the microcantilever bending always occur before any measurable resonance frequency shifts. Monitoring the bending of the microcantilever as molecules adsorb on its surface provides an extremely sensitive means of chemical sensing. In addition, monitoring of resonance frequency changes provides another sensing mechanism similar to the manner SAW and QCM devices operate. The chemical selectivity and reversibility of the present chemical sensor is based on the action of composite self-assembled monolayers. We will report on the response of microcantilevers with composite self-assembled monolayers to DIMP and DMMP. Our results show that such microcantilever chemical sensors exhibit rapid response times and high selectivity to organophosphonate compounds.