A novel passive wireless ultrasensitive RF temperature transducer for remote sensing

A wireless passive ultrasensitive temperature transducer is presented in this paper. The transducer consists of micro bimorph cantilevers (Aluminum-Silicon) and split ring resonators, operating at millimeter wave frequencies around 30 GHz. As the temperature changes, the bilayer cantilevers deflect and thus alter the resonant frequencies of the resonators. The design achieves a sensitivity of 1.05 GHz/um with respect to cantilever deflection, corresponding to a sensitivity of 150 MHz/°C, three orders of magnitude higher than existing passive wireless temperature sensors. The sensor design has high Q factor, is ultra-compact, easily fabricated and integrated with other passive sensors in sensing networks. Depending on material choices, the proposed design can also be utilized in harsh environments. To demonstrate the proof-of-concept, scaled designs around 4 GHz are presented, utilizing Aluminum-PET (Polyethylene terephthalate) bilayer cantilevers, achieves a sensitivity of 2.14 MHz/°C.