No abstract

Abstract-We present a new miniaturized (below 1 mm ) temperature sensor based on microfluidic technology and radar passive interrogation principles, which can be easily applied for temperature telemetry for medical applications. The chipless microsystem is made up of a planar-gap capacitor with a microchannel located in between its plates. The temperature-dependent expansion/shrinkage of the water inside the microchannel modifies in a monotonic way the liquid level across the capacitor. The resulting change in the effective permittivity modifies the capacitance value in a temperature-dependent way. The first prototypes of the temperature microsensor were micromachined and integrated with an antenna, while the ambient temperature was remotely measured using frequency-modulated continuous-wave (FMCW) radar interrogation principles at 29.75 GHz. Preliminary measurement results demonstrated a 0.4 dBm sensitivity over a 9 temperature range (24 -33 ).Index Terms-Electromagnetic transduction, frequency-modulated continuous-wave (FMCW) radar, medical telemetry, microfluidic, passive and chipless sensor, remote sensing, temperature microsensor, wireless sensor.

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.