Passive multivariable RFID pH sensors

Sensing of pH with single-use gamma sterilizable sensors is needed in single-use bioprocess components. In this study, we explored pH sensing films based on polyaniline (PANI) that were deposited onto our recently developed passive radio-frequency identification (RFID) sensors. Two main strategies for developing pH sensitive PANI films involved doping PANI with camphorsulfonic acid (CSA) and poly (styrene sulfonate) (PSS). The PANI-PSS films demonstrated the most stable response. The possibility to perform pH measurements over a range of conductivities was explored using multiple parameters of the measured resonance impedance of the RFID sensor.