Phenomenological theory and experimental characterizations of passive wireless EM pressure micro-sensor prototype

In this paper, the new and latest results relative to theoretical and experimental studies of an original passive electromagnetic micro-sensor for wireless pressure monitoring application are presented. This micro-sensor uses the electromagnetic transduction principle. The sensing element is a flexible high resistivity silicon membrane located above a coplanar quarter-wavelength resonator operating in Ka-band. When an external pressure acts on the membrane, it changes the electrical properties of the resonator and in turn changes the resonant frequency. The sensor design covers diverse disciplines such as microwaves, materials, microfabrication, and mechanics. A comprehensive coverage of the physical bases is beyond the scope of this paper. For the first time, theoretical results, based on the transverse analysis method, describe the physical phenomenon which intervenes in the transduction. This sensor is fabricated and on wafer RF, pressure and temperature measurements are presented. This pressure cell is not only an EM based pressure sensor but it is considered also as passive wireless pressure measurement device: proof of concept is given in this paper.