Deformable Humidity Sensor and its Performance Based on Double-Network and Ionic Conductive Hydrogel Membrane

This paper reported a double-network (DN) ion-conducting hydrogel membrane sensor for humidity sensing. Lithium bromide was introduced into the hydrogel by the simple immersion method to improve the antifreezing, anti-drying ability and moisture sensitivity of the hydrogel. Also, this sensor exhibited deformability (withstand 100% tensile strain), high transmittance in the visible light range (above 89%), and a wide relative humidity (RH) detection range (22-98%). The sensitivity of the membrane humidity sensor prepared in this paper was greatly improved compared to the bulk hydrogel sensor. For example, the sensor's response at 98% relative humidity was increasing 16,280 times. It was found that the response has an exponential relationship with relative humidity. Also, this humidity sensor based on a hydrogel membrane can detect changes in the relative humidity of the environment caused by human breathing and finger contact.