Optical Voltammetry Closed-Cell Bipolar Electrochemistry Based Sensor for Portable Low-Cost Heavy Metal Water Testing

Abstract

Events such as the ongoing Flint, MI and Newark, NJ water crises highlight the need for reliable large-scale water quality assurance. Currently available options for water testing such as laboratory analysis and commercial test strips fail to adequately provide a description of potential water issues for they are expensive, time consuming and rely on technical expertise, being practically futile for the layman and for identifying and preventing large water crisis. Our group developed a new analytical apparatus and mechanism for the detection of metals in water, which is portable, quick, accurate, cost-efficient and can be readily adapted for different deployment needs. The apparatus employs a two-step protocol of optical anodic stripping voltammetry in a readily parallelizable closed-cell bipolar electrode format and is produced under a quick and cost-effective fabrication protocol. Additionally, the fabrication utilizes readily adoptable techniques such as laser cutting as opposed to costly clean-room fabrication techniques. The tool can also be further adapted to employ other commonplace technologies such as printers and smartphones. Previous work from this lab had effectively utilized electrochemiluminescence as reporting mechanism but has now moved onto more consistent light-emitting diodes with improved linearity over several orders of magnitude, increased re-usability and limits of detection now in the sub-ppb range. This new sensing scheme utilizes a simple power supply to couple an anodic stripping event at one pole of the bipolar electrode with an LED emission which is externally recorded and processed thereby avoiding additional costly, non-portable conventional potentiostatic circuitry. In this format, near 100% faradaic efficiency can be achieved as well as facile parallelization for simultaneous sensing of multiple electroactive species. The apparatus and mechanism show great promise as a new deployable analytical tool which can be further engineered to non-electroactive species such as PFAs and to even-lower cost techniques and user-friendly protocols for unprecedented large-scale water quality assurance. Figure 1