| This paper presents optimum design of circular membrane for high quality factor. A quality factor of CMUT, we designed for resonant chemical sensor, is dominated by Qair and Qsupport. We investigated these two factors independently. We calculate Qair of circular silicon membrane analytically, and numerically. Calculated Qair is compared to measured value. In order to find Qsupport empirically, we measured quality factor of CMUT in vacuum chamber. Qair is proportional to (radius/thickness)-2 and Qsupport is proportional to (radius/thickness)3. Thus the optimum aspect ratio of membrane exists for maximum quality factor. |