Highly transparent and flexible polyaniline mesh sensor for chemiresistive sensing of ammonia gas.

A new structure of a flexible, transparent polyaniline (PANI) ammonia gas sensor is reported. The sensor features a hierarchical nanostructured PANI polymer arranged in a micromesh, exhibiting excellent chemiresistive sensitivity to ammonia gas and near-neutral color transparency. The PANI mesh is embedded in a flexible substrate and therefore exhibits superior mechanical stability against peeling and bending. These merits make it a promising candidate for application in wearable electronics. Moreover, the PANI mesh sensor is fabricated through a cost-effective, solution-based strategy that enables vacuum-free fabrication of a sacrificial catalytic copper mesh followed by in situ polymerization, and this strategy is scalable for high-volume production. We demonstrate the high-performance resistive sensing of ammonia gas with concentrations from 2.5 ppb to 100 ppm using this flexible PANI mesh sensor with an excellent transparency of 88.4% at 600 nm wavelength. Furthermore, no significant degradation in the sensing performance occurs after 1000 bending cycles.