Gas and liquid phase sensing of volatile organics with disk microresonator

The sensing of volatile organic compounds (VOCs) using a MEMS resonator with an in-plane vibrational mode is reported. VOCs are detected in both the gas and liquid phases by a polymer-coated disk microresonator, which is operated as the frequency determining element in an amplifying feedback loop. The functionalized disk microresonators exhibit a short term frequency stability of 1.1 times 10
^-7
in air and 3.4 times 10
^-6
in water. Using polymer membranes as chemically sensitive layers, different concentrations of o-xylene, benzene, octane, trichloroethane, and toluene have been detected in the gas phase, with the limit of detection for o-xylene being 2.2 ppm. M-xylene has been detected in the liquid phase with a limit of detection of 1.9 ppm.