Optimal Temperature Sensor Based on a Sensitive Material

*Asma Bakkali, José Pelegri-Sebastia, Youssef Laghmich and Abdelouahid Lyhyaoui*

### **Abstract**

The context of this chapter is the development of passive sensors for temperature sensing applications. The purpose is to successfully reduce the energy consumption in wireless sensor networks. The sensor is based on the electromagnetic transduction principle, and its originality is based on the integration of a high temperature-sensitive material into passive structure. Variation in temperature makes the dielectric constant of this material changing, and such modification induces variation in the resonant frequencies of high-Q whispering-gallery modes in the millimeter-wave frequency range. In this way, the proposed device shows a linear response to the increasing temperature, and these variations can be remotely detected from a radar interrogation of an antenna loaded by the whispering-gallery mode resonator. Proposed device is a powerful tool for many interesting applications since it offers very low power consumption and provides environmentally friendly temperature measurement. The sensor is simulated in order to outline its performance and to show the benefit of the batteryless sensing device.

**Keywords:** energy consumption, wireless sensor networks, lifetime, energy conservation, whispering gallery mode, PLZT material, temperature, dielectric resonator
