The PEDOT: PSS/PNIPAM hydrogel was simply prepared by ultrasound-enhanced free radical polymerization in an ice bath, in open air rather than spending hours under an N2 purged environment. The resulting conductive hydrogel had a uniform texture and good flexibility for rapid resistance responses and color changes when it was exposed to temperature stimulations. The dual actions of hydrogen bonding and hydrophobic aggregation weaken the Coulomb interaction between PEDOT+ and PSS− for better conductivity that is suitable for breathing monitoring and other wearable sensing applications.
