Abstract: A method of fabricating a thickness shear mode (TSM) gas and organic vapor sensor having a visco-elastic polymer coating and a fundamental frequency greater than 20 MHz. The method begins by providing a piezoelectric crystal and milling a central region of the crystal. Milling the crystal creates a central oscillating region of reduced thickness surrounded by a thicker outer region. Two electrodes are then deposited in the oscillating region of the crystal—one on each side of the crystal. The oscillating region on both sides of the crystal and the electrodes are then coated with a polymer coating.

Abstract: A thickness shear mode (TSM) sensor having a visco-elastic polymer coating and a fundamental frequency greater than 20 MHz useful for organic vapor or gas detection. The TSM quartz resonators at a fundamental frequency of 96 MHz were evaluated for their performance in organic vapor sensing applications and results were compared with the performance of 10 and 20 MHz resonators. These devices were produced by chemical milling of AT-cut quartz. Seven test organic vapors were utilized at concentrations ranging from 0.2 volume percent to 13.7 volume percent in the vapor phase. In all cases, the rubbery polymer polyisobutylene was used as a sensing layer. Detailed results for various sensor parameters such as sensitivity, baseline noise and drift, limit of detection, response and recovery times, dynamic range, and repeatability for the 96 MHz device were compared with those for 10 and 20 MHz devices. The test case of benzene/polyisobutylene was chosen to make these detailed comparisons.

Abstract: A thickness shear mode (TSM) sensor having a visco-elastic polymer coating and a fundamental frequency greater than 20 MHz useful for organic vapor or gas detection. The TSM quartz resonators at a fundamental frequency of 96 MHz were evaluated for their performance in organic vapor sensing applications and results were compared with the performance of 10 and 20 MHz resonators. These devices were produced by chemical milling of AT-cut quartz. Seven test organic vapors were utilized at concentrations ranging from 0.2 volume percent to 13.7 volume percent in the vapor phase. In all cases, the rubbery polymer polyisobutylene was used as a sensing layer. Detailed results for various sensor parameters such as sensitivity, baseline noise and drift, limit of detection, response and recovery times, dynamic range, and repeatability for the 96 MHz device were compared with those for 10 and 20 MHz devices. The test case of benzene/polyisobutylene was chosen to make these detailed comparisons.