Flow automatic system using an ion-selective field-effect transistor for the real-time/online detection of ammonium ions in aquaculture water

•A novel real-time flow automatic system with NH4+-ISFET sensor was reported.•It offered excellent performance, a wide linear range, high sensitivity, and long lifetime.•It successfully determined NH4+ in aquaculture water samples.•It can be monitored online anywhere and anytime using internet-connected devices. Aquaculture systems necessitate vigilant monitoring of water quality parameters to ensure optimal conditions for aquatic life. Ammonium ion (NH4+) concentration stands as one of the critical factors, influencing the health and productivity of aquatic organisms. This study focuses on the development and implementation of a real-time flow automatic system, utilizing ion-sensitive field-effect transistor (ISFET) technology for the precise detection of ammonium ions in aquaculture settings. The proposed system integrates ISFET sensors within a flow automatic system to enable continuous and automated monitoring of NH4+ concentrations in aquaculture ponds or systems. The ion-selective membrane (ISM) on a printed circuit board was prepared by drop casting a mixture of nonactin as an ammonium ionophore and poly(vinyl chloride-co-vinyl acetate-co-vinyl alcohol) and dioctyl sebacate to create an NH4+-ISFET sensor. The limit of detection was found to be 0.06 mg L−1 with a linear range of 0.1 – 1000.0 mg L−1 and an R2 of 0.9986 at a sensitivity of 61.29 mV dec−1. The NH4+-ISFET sensor had a useful lifetime of more than 8 months. Leveraging the high sensitivity and rapid response capabilities of the ISFET sensors, the system facilitates instantaneous detection and real-time quantification of ammonium levels and allows monitoring of ammonium concentrations anywhere and anytime using internet-connected devices. This proposed system emphasizes the significance of the real-time ISFET monitoring system to enhance water quality in aquaculture while mitigating the risks associated with fluctuating ammonium levels in aquatic environments. [Display omitted]