A Self-Powered UHF Passive Tag for Biomedical Temperature Monitoring

Self-powered RF passive sensors have potential application in temperature measurements of patients with health problems. Herein, this work presents the design and implementation of a self-powered UHF passive tag prototype for biomedical temperature monitoring. The proposed battery-free sensor is composed of three basic building blocks: a high-frequency section, a micro-power management stage, and a temperature sensor. This passive temperature sensor uses an 860 MHz to 960 MHz RF carrier and a 1 W Effective Isotropic Radiated Power (EIRP) to harvest energy for its operation, showing a read range of 9.5 m with a 13.75 mu W power consumption, and an overall power consumption efficiency of 10.92% was achieved. The proposed device can measure temperature variations between 0 degrees C and 60 degrees C with a sensitivity of 823.29 Hz/degrees C and a standard error of 13.67 Hz/degrees C over linear regression. Circuit functionality was validated by means of post-layout simulations, characterization, and measurements of the manufactured prototype. The chip prototype was fabricated using a 0.18 mu m CMOS standard technology with a silicon area consumption of 1065 mu m x 560 mu m. The overall size of the self-powered passive tag is 8 cm x 2 cm, including both chip and antenna. The self-powered tag prototype could be employed for human body temperature monitoring.