Colorimetric sensing platform based on Lab-on-a-chip for ammonia detection in water

Abstract

Ammonia, a compound of nitrogen and hydrogen, is highly corrosive, toxic, and harmful to living organisms when exposed to high concentrations. It is also a known cause of water pollution when released in large quantities. This common source of ammonia in agriculture and factories requires continuous monitoring and rapid field measurements to prevent water pollution. Various methods exist for monitoring ammonia, with electrochemical and optical methods being the primary ones. Conventional methods face challenges such as sensor longevity, size, and low detection limits. In this study, lab on a chip module was fabricated for ammonia measurement. The developed device comprises three distinct parts: a mixing part, a reaction part, and a measuring part. It is designed to be compatible with microfluidic chips, allowing for the continuous utilization of the platform. The replacement of the microfluidic chip is the only maintenance required, making the device cost-effective for ammonia measurement in water. The ammonia concentration was measured using a colorimetric detection method on the lab-on-a-chip detection unit, using a 20% v/v dilution of Nessler's reagent and the reaction product of the ammonia sample with the AS 7262 spectral sensor. To facilitate straightforward measurements on the developed platform, 3D computer-aided design software was used to create a digital model, which was then produced using a 3D printer employing the 3D modelling technique.