A novel highly reversible humidity sensor based on poly(2-propyn-2-furoate)

Thin film humidity sensors were prepared with salt-doped poly(2-propyn-2-furoate) (PPF). The humidity sensitive properties of the sensors have been investigated by measuring the complex impedance spectroscopy at different relative humidities (RHs). Both impedance and capacitance of the sensors change 3–4 orders of magnitude from 33 to 97% RH, and no hysteresis is observed. In addition, the capacitance responses exhibit good linearity for PPF doped with LiCl (R2=0.9995) and FeCl3 (R2=0.9996) over a wide humidity range. It is proposed that the highly reversible impedance and capacitance responses are related to the furan ring in PPF.