Electrostatic adhesion of polyaniline on carboxylated polyacrylonitrile fabric for high-performance wearable ammonia sensor

Wearable ammonia sensors based on the flexible substrates find a wide applications in portable electronics and healthcare. However, the interfacial adhesion of sensing materials on the flexible substrates is always weak. Here, polyacrylonitrile (PAN) fabric is hydrolyzed in alkaline conditions to produce carboxyl groups on the surface, which improves the loading of aniline followed by in-situ chemical polymerization. The prepared conditions of polyaniline (PANI) coated PAN fabric (PANI@PAN) are optimized and the ammonia sensing properties of PANI@PAN at room temperature are evaluated. PANI@PAN shows a high sensitivity (S = 10.3 at 100 ppm ammonia), a broad linear range with excellent linearity (1.5-1500 ppm, R2 = 0.997) and a good selectivity, which is attributed to the high loading of PANI with nanofiber morphology. Moreover, because of the strong electrostatic interaction between PANI and PAN, PANI@PAN sensor also exhibits satisfactory stability against bending and washing. These properties reveal the promising application of PANI@PAN fabric in wearable ammonia sensor.