Cactus-Like\nNiO Nanostructure-Based ppb Level Trimethylamine\nGas Sensor for Monitoring Saltwater Fish Freshness

This paper presents a cactus-like NiO nanostructure-based\nchemiresistive\ngas sensor for monitoring saltwater fish freshness. The sensing material\nwas synthesized via a low-temperature, facile hydrothermal method.\nThe cubic crystal system and cactus-like morphology of the synthesized\nmaterial were revealed using X-ray diffraction and a field emission\nscanning electron microscope. The sensing material was integrated\nwith gold interdigitated electrodes for gas sensing measurements.\nThe operating temperature of the sensor was optimized to be 250 °C.\nThe fabricated sensor was more sensitive toward trimethylamine (TMA).\nA response of 56% was obtained in the presence of 10 ppm trimethylamine\nwith the response and recovery times being 30 and 205 s, respectively.\nThe experimental limit of detection of the sensor was 100 ppb. The\nsensor was exposed to vapors emitted from saltwater or marine fish.\nFish samples were categorized according to the storage conditions\nof room temperature and deep fridge. The sensing measurements were\nperformed with fish samples at a time interval of 24 h. Initially,\nthe response of the sensor to a fresh sample was around 10%. After\nthat, the response of the sensor increased with time. This study suggests\na simple method for detecting marine fish freshness using chemiresistive\nsensing technology in a sensitive and efficacious manner.