On-Chip Optical Anodic Stripping Voltammetry with Closed-Cell Bipolar Electrode Arrays for Heavy Metals Detection in Water

Abstract

A dynamic understanding of metals in water requires an equally dynamic, sensitive, and ideally, deployable analytical process. Standard instrumental techniques are typically expensive, require technical expertise for operation, are time-consuming, and are inherently non-portable. While electrochemistry fits the bill for most criteria, it has long been limited by analysis speed and portability. We developed a new low-cost closed-cell bipolar electrochemical technique that couples conventional anodic stripping voltammetry with on-chip optical readout in an inherently parallelized fashion. This presentation will introduce our new sensing scheme which couples a new cathodic electrochemiluminescence (ECL) reaction at one pole of the bipolar electrode with an anodic stripping event of a heavy metal (i.e. Pb) at the opposite pole. When the chip is operated in a close-cell bipolar format, near 100% Faradaic efficiencies can be achieved. The influence of both the physical chip design as well as the electrolyte composition on the sensor functionality will be described. A rapid and economical fabrication protocol will be described which supplants typical cleanroom microfabrication tactics with simple programmable laser ablation on conductive glass substrates. Recent efforts towards replacing ECL readout with an all solid-state transduction mechanism will also be highlighted, with an emphasis on significantly increasing the analysis precision and chip reusability while achieving detection limits in the single part per billion range. Finally, sensor parallelizability will be discussed.