Thinner is Better: An Ultrathin Conducting Oligoaniline Film for Gas Microsensors with Ultralow Detection Limits

An ultralow-limit gas microsensor based on an ultrathin conducting oligoaniline film integrated with microscale gold electrodes is developed. A nanoscale oligoaniline film is fabricated on a poly(dimethylsiloxane) (PDMS) substrate using graft polymerization using FeCl₃, a mild oxidant, rather than conventional (NH₄)₂S₂O₈. The as-fabricated film is around 14 nm in thickness and above 85% transmittance on a PDMS substrate with a smooth surface morphology and high conductivity. Taking NH₃ as a protocol, the nanoscale oligoaniline film microsensor shows an ultralow detection limit to the ppb level with more rapid response and high sensitivity to NH₃ compared to the thicker PANI film using conventional methods.