Feasibility Study on the Reading of Energy-Harvested Implanted NFC Tags Using Mobile Phones and Commercial NFC IC

Abstract

This paper studies the feasibility of reading implanted sensors based on battery-less Near-Field Communication (NFC) integrated circuits using an NFC-equipped smartphone as a reader. Different commercial NFC integrated circuits (IC) with energy harvesting capability are compared. A conventional system based on the resonant coupling between 2 coils is compared with a system proposed here consisting in the resonant coupling between 3 coils. In the latter, a relay antenna is implemented on a patch and attached on the skin. A measurement setup to characterize the read range of the NFC implanted sensors is built up. Experimental results show that the 3 coils system presents a much better performance. The prototype of the implanted tag consisted of an $\boldsymbol{15 \ \times 15\ \mathbf{mm}}$ antenna and a commercial NFC IC with energy harvesting that is able to read up to 16 mm inside the body using commercial smartphones.