A passive temperature sensor based on a printed magnetoinductive-wave (MIW) delay line

Novel fully passive and electromagnetic sensors are proposed. These sensors are implemented with magnetoinductive-wave (MIW) delay lines. Such lines are composed of a periodic array of coupled square split ring resonators (SSRRs) and propagate slow waves. A reflector with a transducer element (temperature, moisture, etc.) is coupled to the end of the MIW line. When the sensor is interrogated with a pulse in time domain, the reflector produces a replica of the original pulse modulated in amplitude, which depends on the magnitude under sensing. Thanks to the slow group velocity of the MIW delay line, the replica and the original pulse are not overlapped in time domain and can be demodulated, thus obtaining a measurement of the magnitude. A design of a temperature sensor based on the proposed technology is presented. The reported results validate the proposed approach and the feasibility of the proposed application.