RFID-based dual-chip epidermal sensing platform for human skin monitoring

Wireless epidermal devices based on Radio frequency Identification (RFID) enable a contactless and non-invasive monitoring of the human body by sampling health parameters directly on the skin. To achieve multi-parametric sensing, while preserving the intrinsic simplicity and the low cost of RFID tags, a dual-chip epidermal device is here proposed. At this purpose a polarization-diversity loop antenna is exploited so that two almost independent current modes are excited. The resulting radiation patterns are both broadside, thus enabling the simultaneous gathering of two independent dataset from the same maximum distance. A 3.5 by 3.5 cm battery-less, flexible and soft prototype provides -13 dBi embedded realized gain with read distances ranging from 0.6m to 1.5m depending on the microchip sensitivity. The electromagnetic performance of the two ports remain similar even when the tag is applied onto rather in-homogeneous body regions. With reference to body temperature monitoring, the device has been experimented in both controlled and real-life environments, demonstrating the possibility of doubling the sensing capabilities of RFID epidermal devices without affecting their size and radiation performances.