High Sensitivity Humidity Sensor and Its Application in Nondestructive Testing for Wet Paper

In this paper, a capacitive-type humidity sensor based on TiO2/Ag nanoparticle composites film was fabricated on interdigital electrodes. Experimental results showed that a small amount of Ag nanoparticles mixed with TiO2 nanoparticles could greatly improve the sensor sensitivity. Compared with pure TiO2 sample, the improved capacitance variation of sensor raised more than two orders of magnitude. The reduction in water contact angle measurements proved that the hydrophilicity of the film had increased, and the appearance of Warburg impedance at 11% RH in the complex impedance spectra plot indicated that adding Ag improved the absorption ability of composite film. This high-sensitive humidity sensor proposed in this work could enable the non-destructive detection of wet paper and had potential applications in the preservation of ancient manuscripts, historical calligraphies and paintings.