All-inkjet-printed microfluidics-based encodable flexible chipless RFID sensors

This paper proposes the first-of-its-kind microfluidics-based encodable and flexible chipless RFID sensors. The prototype, including the microfluidic channels and passive RFID resonators, is manufactured cost-efficiently with sole reliance on multilayer inkjet-printing for the first time. Three microfluidics-based reconfigurable spiral resonators are used to obtain tunable “code” frequencies and encode the RFID with less than 0.5 µL of water per bit. The embedded microfluidics also facilitate sensing of various fluids (e.g. identifying different water-glycerol mixtures). The proposed chipless RFID module maintains a stable performance during bending and can be bent for radii down to at least 12 mm. The proposed encodable chipless RFID module can be used in various application spaces including healthcare monitoring, food quality sensing and liquid leakage detection.