Working principle description of the wireless passive EM transduction pressure sensor

¹ CNRS-LAAS, 7 avenue du Colonel Roche, 31077 Toulouse, France
² University of Toulouse, UPS, INSA, INP, ISAE, LAAS, 31077 Toulouse, France

^a e-mail: mjatlaou@laas.fr

Received: 30 May 2010
Revised: 4 July 2011
Accepted: 1 August 2011
Published online: 28 September 2011

Abstract

The development of a new passive wireless pressure sensor, based on an electromagnetic transduction approach, is reported. The sensing element is a flexible high resistivity silicon membrane located above a coplanar quarter-wavelength resonator. The comprehensive coverage of the physical bases is beyond the scope of this paper. For the remote extraction of the applied pressure value, the passive pressure sensor is connected to a broadband horn antenna via a coaxial delay line. When interrogated by a frequency modulated continuous wave radar, the level of the backscattered signal changes versus the pressure applied to the proof body. Through this interrogation principle, the sensor provides load impedance that is reflected back to the radar reader: the measured dynamic is about 0.8 dBm/bar. This completely passive and wireless pressure telemetry micro-sensor has been designed, fabricated and characterized, thereby eliminating the need for contact, signal processing circuits, and power supplies needed by conventional active sensors.