Au loaded mesoporous SiO2/gelatin hydrogel: Detecting low humidity and NH3

In this paper, a composite hydrogel film (Au/Me-SiO 2 /G) based on Au nanoparticles, mesoporous silica and gelatin was prepared, which can be used for low relative humidity (RH) detection. Au-1%/Me-SiO 2 /G exhibits a response of 423% in the range of 0.4–30% RH, a short response time of 28 s, a linearity of R 2  = 0.997, and good long-term stability. With the outstanding ability to adsorb water molecules, the sensor can detect NH 3 at room temperature and low humidity environment. The response of the sensor to NH 3 significantly increases with the humidity. At 30% RH, the initial impedance value of the sensor is as low as ∼6.6 MΩ, and the response to 50 ppm NH 3 is 78%. In addition, an egg storage scenario was simulated, and the water loss in eggs was monitored simultaneously by the prepared humidity sensor and a commercial sensor. The results demonstrate the practical application detection ability of the prepared humidity sensor.