Combinatorial screening of polymeric sensing materials using RFID sensors: combined effects of plasticizers and temperature.

Recently, we have developed battery-free, passive RFID chemical and biological sensors that are attractive in diverse applications where sensor performance is needed at a low cost and when battery-free operation is critical. In this study, we apply this attractive low-cost sensing platform for the combinatorial screening of formulated sensing materials. As a model system, a 6 x 8 array of polymer-coated RFID sensors was constructed to study the combined effects of polymeric plasticizers and annealing temperature. A solid polymer electrolyte Nafion was formulated with five different phthalate plasticizers: dimethyl phthalate, butyl benzyl phthalate, di-(2-ethylhexyl) phthalate, dicapryl phthalate, and diisotridecyl phthalate. These sensing film formulations and control sensing films without a phthalate plasticizer were deposited onto 9-mm diameter RFID sensors, exposed to eight temperatures ranging from 40 to 140 degrees C using a gradient temperature heater, and evaluated for their response stability and gas-selectivity response patterns. This study demonstrated that our RFID-based sensing approach permits rapid cost-effective combinatorial screening of dielectric properties of sensing materials.