Effect of polymer thickness on the chemical sensing behavior of polymer-coated mass-sensitive disk resonators

The chemical sensing behavior of disk microresonators, as it is affected by the thickness of polymer coatings applied to them, is reported. The disk microresonators were fabricated using a CMOS-compatible silicon bulk micro machining process. The disks were subsequently coated with layers of (poly) isobutylene (PIB) as a sensing film and exposed to gaseous benzene, toluene, and m-xylene. The experimental results agree well with analytical models derived for both the chemical sensitivity and limit of detection (LOD). Minimal LODs measured for benzene, toluene, and m-xylene were 5.3 ppm, 1.2 ppm, and 0.6 ppm, respectively.