Temperature sensing is critical in many automotive, medical, and industrial systems for applications such as engine operations, space shuttle and aircraft in-flight conditions, and road and bridge health. A passive wireless temperature sensor would enable remote sensing and long term monitoring for those applications. Most existing temperature sensors require a power source, and ones with high sensitivity suffer from performance degradation above 130 C . A capacitively-loaded MEMS slot element for wireless temperature sensing was proposed in  but has very low sensitivity of about 500 kHz/ C. In this work, the authors introduce a new wireless passive ultrasensitive temperature transducer based on split ring resonators (SRR) that can be integrated into wireless multiphysical sensing platforms. The new temperature transducer achieves an ultrahigh sensitivity of about 780 MHz/ C. Furthermore, improving the technique reported recently in , the authors also propose a new micro-sensor identification technique based on loaded multi-band scatterers whose radar cross section (RCS) read by a frequency modulated continuous wave (FMCW) radar. In this paper, a prototype of the novel SRR temperature sensor integrated into the passive multi-sensor identification sensing system is demonstrated as well as RCS measurements.