Microelectrode arrays for in situ measurement of redox potentials

This paper describes a microelectrode array (MEA) sensor system for measurements of oxidation-reduction potentials (ORP) in situ in the environment. The four-probe MEAs were fabricated from glass using a two-step, HF-based meniscus etching process. A CMOS ASIC chip was developed for signal acquisition and processing and packaged with the microelectrode sensors to reduce noise. The electrochemical performance of these ORP MEAs was fully characterized by measuring redox potentials of standard and reference solutions. The MEAs exhibited a substantially faster response time, proved to be extraordinarily stable, and were independent of the microelectrode position within the array.