The effect of channel height and electrode aspect ratio on redox cycling at carbon interdigitated array nanoelectrodes confined in a microchannel

Abstract

Redox cycling is a commonly used electrochemical sensing scheme for enhancing faradaic current signals. This effect can be improved by either optimizing electrode geometries or restricting electrochemical reactions within a limited volume. Here, we demonstrate a simple batch fabrication of 1 : 1 aspect ratio carbon interdigitated array nanoelectrodes integrated in a polydimethylsiloxane microchannel that enables current amplification by up to 1116 times. We also examine the factors that influence the effect of redox cycling, including the electrode aspect ratio and channel height, by using experiments and simulations.

SU-8-based Flexible Amperometric Device with IDA Electrodes to Regenerate Redox Species in Small Spaces

“…Compared to other IDA electrodes, 14 the signal amplification and the collection efficiency of the present device are low. For improving the signal amplification and the collection efficiency, it is necessary to modify the geometric features of the electrodes, including their spacing, width, and aspect ratio because the signal amplification and the collection efficiency of IDA electrodes depends on the geometric features.…”

“…For improving the signal amplification and the collection efficiency, it is necessary to modify the geometric features of the electrodes, including their spacing, width, and aspect ratio because the signal amplification and the collection efficiency of IDA electrodes depends on the geometric features. 14 To analyze the behavior of redox cycling in small spaces precisely, current simulations were performed. Simulations were carried out to determine the effects of confinement on the redox current by varying the channel height in the model, as illustrated schematically in Fig.…”

“…Such electrodes have two interdigitated comb-type arrays consisting of planar parallel fingers. [8][9][10][11][12][13][14][15][16] When a suitable potential is applied to each electrode, species that become oxidized at one electrode finger are regenerated at neighboring fingers, resulting in redox cycling for amplification of the electrochemical signal. Such IDA electrodes have been applied for electrochemical detection of enzyme activity, [8][9][10][11][12][13] and have also been fabricated on a gas-permeable membrane to produce a gas-sensing system.…”

Glucose sensor based on redox-cycling between selectively modified and unmodified combs of carbon interdigitated array nanoelectrodes

“…Interdigitated microelectrodes with a high aspect ratio fabricated using selective deposition of a conductive layer onto a pre-patterned silicon structure also showed high signal amplification, comparable to that of nano-gap IDA devices [4]. Recently, our group demonstrated the simple fabrication of carbon IDA nanoelectrodes with 1:1 aspect ratios using carbon-microelectromechanical system (C-MEMS) technology; this nanoelectrode architecture successfully achieved current amplification as high as 1,116 times in a microchannel [5].…”

“…The C-MEMS fabrication procedure of the 1:1 aspect ratio carbon IDA nanoelectrodes is described in detail elsewhere [5]. First, a 3-µm-thick photoresist was patterned to form IDA microstructures using photolithography on a 6-inch silicon wafer passivated by a 1-µm-thick thermally grown silicon dioxide layer.…”