Onsite fish quality monitoring using ultra-sensitive patch electrode capacitive sensor at room temperature

Fish freshness plays a vital role in the fish industry and also affects human health from a nutrition point of view. Here, an Au metal patch electrode capacitive sensor is introduced for rapid and accurate detection of volatile gases generated from raw fish to determine its freshness status. The MIS structured sensor was fabricated on a silicon substrate using Ag-SnO₂ as sensing material over SiO₂ layer and Au as a metal electrode. The calibration of the sensor was carried out with known composition of volatile gases (NH₃, TMA, DMA and H₂S) in the ppb-ppm regime. Our sensor using the proposed technique delivers sensor response to raw fish within 4 min, reflecting its freshness status in comparison to the TVB-N and TVC method which takes many hours to complete involving many sophisticated steps. The sensor response to volatile gases from Rohu (Labeo Rohita), Tilapia (Oreochromis Niloticus) and Illish (Tenualosa Ilisha) obtained by using our developed sensor system at 20 °C, 25 °C, and 30 °C, shows high correlation with TVB-N and TVC results. The acceptance limit for safe consumption of Tilapia, Rohu, and Illish at 30 °C was found to be 11 h, 12.5 h, and 10 h of storage time respectively. The result in this work assures a portable low-cost sensor for onsite monitoring of fish freshness at room temperature.