A Disposable Multiplexed Chip for the Simultaneous Quantification of Key Parameters in Water Quality Monitoring

On-site simultaneous quantification of multiple contaminants in a water body is challenging, especially for parameters requiring complicated chemical reactions to measure such as Chemical Oxygen Demand (COD), ammonia nitrogen, and phosphate. A novel disposable multiplexed microfluidic device has been developed herein that allows the quantitative detection of up to five parameters at once. Solid reagent rather than commonly used liquid reagent was used to ensure long shelf life, and a "flow to dissolve" mechanism was provided accordingly for the thorough dissolution and mixing of a solid reagent on chip. Samples from river water and industrial wastewater were tested using the microfluidic chip, showing less than 15% deviation from results acquired with the traditional standard method. The test time though was only 1/6 of that required by the traditional method. In addition, the feasibility of using a smartphone to collect the colorimetric signal was discussed, and a data analysis method was provided for quantification purposes. The combination of the multiplexed chip and smartphone imaging provides a convenient and practical way to obtain accurate information on the water quality within a short period of time without the use of any sophisticated instruments.