Ultra Low Power Wireless Epidermal Sensor for Battery-less pH monitoring in the sub-6 GHz 5G band

RFID epidermal electronics recently gave us the possibility to connect our body to the external world and gather information about our health and state directly from the skin. To increase the acceptance of the monitoring platforms and overcome the limitations of current technology, i.e. the need of a dedicated reader and a limited bandwidth, new architectures of battery-less backscattering-based communications have been considered. Among them, 5G appears particularly promising thanks to the large bandwidth, the interoperability among devices and the pervasive coverage. In this perspective, this paper proposes the first epidermal chemical sensor for the sampling of the human sweat and the monitoring of the pH. The device communicates with the external reader through a frequency modulation of the backscattered wave, whose parameters depend on the measured analyte. Early simulations and tests corroborate the feasibility of the approach.