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

• In this paper, proper amount of Ag nanoparticles was added into TiO 2 nanoparticles as sensing film, which could increase hydrophilicity and absorption ability of the sensing film. • The enhancement effect of Ag on humidity performance of the sensors was better than lots of most reports. • This high-sensitivity humidity sensor proposed in this work could enable the nondestructive detection of wet paper and has potential applications in the preservation of ancient manuscripts, historical calligraphies and paintings. In this paper, a capacitive-type humidity sensor based on TiO 2 /Ag nanoparticle composites film was fabricated on interdigital electrodes. Experimental results showed that a small amount of Ag nanoparticles mixed with TiO 2 nanoparticles could greatly improve the sensor sensitivity. Compared with pure TiO 2 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 nondestructive detection of wet paper and had potential applications in the preservation of ancient manuscripts, historical calligraphies and paintings. [ABSTRACT FROM AUTHOR]