Carbon black nanoparticles modified gelatin composite-based thin film for rapid-response humidity sensing

Abstract

Humidity monitoring is essential for food processing, pharmaceutical, and precision electronics industries. Conventional humidity sensors based on metal oxides and ceramics show an ideal response to variation humidity. However, long response time and complex manufacturing processes pose a challenge for their more comprehensive application and further development. Resistive polymers show promise in antistatic materials and sensor applications. In this study, gelatin composite, a popular water-soluble polymer, is mixed with carbon black nanoparticles for better humidity sensitivity. Using the state-of-the-art thin film deposition method, the designed interdigitated electrode is covered by a nano-scale thin film of the prepared composite film. The relative humidity range between 20.3% and 83.2% can be well detected according to the evaluation of a customized chemical vapors measurement system. Furthermore, an extreme linear relation and high sensitivity of 0.35mV/%RH are achieved for the range from the relative humidity of 20% to 65.2%. Highly repeatable performance can be demonstrated by repeated experiments with several humidities. Rapid response and recovery features are found during the characterization, while the response and recovery time are lower than 10 s.

A thin film resistive humidity sensor based on polymer and carbon black nanoparticle composites

“…The sensing mechanism is stated as follows: upon exposure to water vapor, the composite film undergoes a reversible absorption of water molecules, resulting in controlled swelling. The film's conductivity predominantly hinges on the moisture content, coupled with alterations in the separation among CB nanoparticles as the composite film undergoes deformation [37]. At lower CB content, as the concentration increases, there is a slight decrease in resistivity, and during this section of the curve, the composite system still exhibits insulating properties.…”