Reducing Charging Currents at Nanowire Sensors: Simulation, Fabrication and Evaluation

In recent years, on-chip nano-electrodes have enabled electrochemical analytical sensors that exhibit enhanced performance. These on-chip sensors have tremendous potential for application in Manufacturing 4.0 paradigms. A key challenge with these sensors is that electric fields, associated with biased interconnection tracks, can induce charge build-up in the electrolyte solution leading to undesirable charging currents superimposed on the Faradaic signals. During in-line measurements, it is very difficult to apply background subtraction techniques accurately; due to variations with time in buffering capacity, flow rate, electrolyte concentration etc. To address this challenge, we explore integration of an on-chip Faraday shield to block and reduce, as much as possible, the formation of these charging currents. Using this approach, we demonstrate a significant reduction in charging current at applied scan rates up to 50 V.s^-1