Wireless interrogation techniques for a passive pressure micro-sensor using an EM transducer

In this communication, the new and latest results relative to 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. From the measurement of the resonant frequency the pressure applied on the membrane can be derived. This completely passive and wireless pressure telemetry micro-sensor has been designed, fabricated and characterized, thereby eliminating the need for contact, signal processing circuits, or power supplies to be contained within the sensor. Measurement results under real working conditions, obtained from a specific RF/pressure bench are reported and reveal a very good sensitivity of 370 MHz/bar in Ka-band. Moreover, for the first time, we propose to use a frequency-Modulated Continuous-Wave (FMCW) radar system for the remote determination of the pressure data via the electromagnetic micro-sensor. This attractive concept of radar interrogated micro-sensor based on electromagnetic transducer is discussed and illustrated.