Epidermal RFID-Based Thermal Monitoring Sheet (R-TMS) for Microwave Hyperthermia

Hyperthermia is an anti-cancer treatment that exploits the interaction between high-power electromagnetic fields and restricted regions of human tissues releasing a great amount of power to locally increase tissues temperature. Due to the high power, dangerous hot-spots may occur on the skin so that continuous monitoring of superficial temperature distribution is required. Thermal Monitoring Sheets (TMSs), which are grids of several wired temperature sensors, are currently used in clinical practice; however, they have some limitations in terms of poor spatial resolution, thermal conduction errors, and complex application procedures. Epidermal electronics associated with passive Ultra High Frequency (UHF) Radio Frequency IDentification (RFID) sensing technology could represent an attractive alternative thanks to its wireless nature and limited invasiveness. In this framework, this article proposes an innovative TMS based on battery-less RFID sensors (R-TMS). It comprises a planar grid of circular loop antennas with temperature-sensing-oriented ICs that can sample skin temperature without interfering with hyperthermia treatment. The system proved capable of monitoring skin temperature via wireless data transmission with a higher spatial resolution that state-of-the-art devices. The physical rationale, the design, and the experimentation of the R-TMS are here presented to validate the proposed approach and evaluate its feasibility from the electromagnetic perspective.