Ultra-High Frequency Band Radio Frequency Identification Tag Enabling Color-Change for Inventory Management Systems: a Color-Change Tag

This paper proposes a radio frequency identification (RFID) tag that can change its color using a piece of a paper towel that has absorbed a solution made from salt and an anthocyanin solution extracted from purple cabbage leaves boiled in water. The proposed RFID tag employs a specific RFID tag integrated circuit (IC) that has energy harvesting and switched ground functions, which enable it to generate direct current (DC) voltages to operate electronic devices and to change a ground terminal connection from a short circuited to an open circuited state, and vice versa. The obtained DC voltages are applied to the paper towel, changing its color from purple to green. The validity of the proposed method was demonstrated experimentally, confirming that the changed colors were preserved after drying. We have succeeded in changing the color of the specified RFID tag at a 75 cm distance using an RFID reader radiating 250 mW radio waves. Furthermore, a laminated paper towel using transparent sheets with electrodes made of two sheets of aluminum foil is presented, changing the color of the paper towel.