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Implementation of Microfluidics Water Pollution Sensor on Autonomous Surface Vehicle (ASV) for Water Quality Monitoring
Group Members
Ang Yeow Sheng, Lai Teng Kang, Lim Si Zhe, New Hui Hong, Annecia Tan Sze Wuan, Yeoh Chew Chen Yew
Dr Niu Xi Ze, Dr Adrian Nightingale
SouthWestSensor Ltd.
The environmental agency has reported that 86% of the river water bodies have failed to achieve good ecological status. Due to agriculture activities, a high concentration of nitrates was released into the environment, which resulted in the accelerated growth of algae, leading to the death of aquatic life. Close monitoring of the nitrate and nitrite levels are essential to controlling and preventing the occurrence of algae bloom before it is too late.

However, traditional water sampling technologies are expensive and labour-intensive procedures, hence low sampling frequencies, which is a poor representation of the dynamic river system. The team proposed a novel technology of implementing an in-situ microfluidic nitrate and nitrite sensor onto a commercial RC boat, modified to navigate autonomously and capable of long-distance communication.

The microfluidic sensor utilised a novel ‘Lab-on-Chip’ microfluidic droplets generation technology, which enabled higher sampling frequency and the usage of microlitre reagent volume to analyse each sample. The concentration of nitrate and nitrite was determined through the colourimetry method, where samples reacted with a reagent to produce a coloured dye, whose intensity is proportional to the nitrate and nitrite concentration. As the boat travelled along the river, nitrite and nitrate concentrations were analysed and timestamped to the location where the samples were collected.

The boat was deployed at River Itchen and collected 65 samples over 125m, creating a spatial map of nitrate and nitrite concentrations. The concentrations measured were 25μM (nitrite) and 260μM (nitrate) upstream and 5μM (nitrite) and 170μM (nitrate) downstream.
Exploded diagram of autonomous boat.