Miniaturized and tunable wearable RFID tag for body-centric applications

A planar “square-smile” like layout is proposed to achieve miniaturized wearable UHF RFID tags. The geometry hosts different slots which contribute to produce size reduction and a two-steps friendly impedance tuning. The resulting antenna surface is half the size of a credit card and permits to be read up to 5m when attached onto the body. Thanks to the flexible and lightweight EPDM foam used as substrate, the tag is suited to be integrated in badges, wallets, pockets, plasters, wristbands and various garments. The particular slotted geometry moreover simplifies the interconnection of chemical or mechanical sensors. An example is given concerning a passive motion detector for the live tracking of human movements and pathological/vital signs in a conventional room.