Optical enhancement strategies on centrifugal microfluidic water sensors for detection of phosphate

Phosphorous is one of the principle elements contributing to eutrophication[1] in coastal, marine and fresh water. This study aims to develop new technologies that can enabled near real-time, rapid, reliable and robust analysis of water nutrient levels, such as phosphate, in water systems. Herein, describes an enhancement study of a previously demonstrated lab-on-a-disc (LOAD) centrifugal microfluidic device for the detection of phosphate in freshwater. The LOAD device utilizes a microfluidic sample processing to enable high precision metering and reagent mixing, followed by colorimetric analysis (at 880 nm) of the resultant complex. A customisable and complementary, in-house analysis system was also developed to enhance user interaction and enable rapid analysis. This analysis system delivers both disc centrifugation and automated colourimetric detection of the LOAD device, with recording of data transmitted via PC interface. The aim of this study is to maintain the same level of sensitivity of the current[2] system with a reduced pathlength. The limit of detection (LOD) and limit of quantification (LOQ) for this new revised system are as follows: The blackened chip obtained the best sensitivity with an LOD and LOQ of 6 and 19 μg L-1 respectively