Paper-Based Microfluidics Platform for Enhanced On-Site Electrochemical Detection of Manganese in Water

Manganese pollution in water has severe toxic effects on biological organisms, including humans. Early detection is crucial to apply timely corrective measures and prevent irreversible consequences. Standard monitoring methods are expensive, time-consuming, and difficult to implement in resource-limited settings, leading to inefficient pollution remediation. The low cost and small size of screen-printed electrodes make them well-suited for on-site analysis but require flow conditions for sensitive results, making them difficult to implement in real-world scenarios. To address this challenge, we present the use of paper microfluidics in combination with screen-printed carbon electrodes for the electrochemical detection of manganese in water. Capillary-driven flow using paper microfluidics provided a practical fluid delivery method for on-site electroanalysis, which was compared to conventional flow methods, i.e., batch setups and flow cells, to demonstrate fitness for purpose. The sensing platform showed a linear response to Mn-(II) up to 200 μg L^-1, with a detection limit of 0.69 μg L^-1, well below the WHO guideline value. The response of the sensor was also analyzed in the presence of potentially interfering metals, and validated in real samples, showing excellent agreement with a standard inductively coupled plasma optical emission spectroscopy method. This approach, inducing flow with paper, is more sustainable, simple, portable, and cost-effective compared to the conventional methods, resulting in a setup with high applicability toward the detection of other pollutants such as metals, PFAS, and pharmaceuticals.