Nanoscale Electrochemical Sensing and Processing in Microreactors

Abstract

In this review, we summarize recent advances in nanoscale electrochemistry, including the use of nanoparticles, carbon nanomaterials, and nanowires. Exciting developments are reported for nanoscale redox cycling devices, which can chemically amplify signal readout. We also discuss promising high-frequency techniques such as nanocapacitive CMOS sensor arrays or heterodyning. In addition, we review electrochemical microreactors for use in (drug) synthesis, biocatalysis, water treatment, or to electrochemically degrade urea for use in a portable artificial kidney. Electrochemical microreactors are also used in combination with mass spectrometry, e.g., to study the mimicry of drug metabolism or to allow electrochemical protein digestion. The review concludes with an outlook on future perspectives in both nanoscale electrochemical sensing and electrochemical microreactors. For sensors, we see a future in wearables and the Internet of Things. In microreactors, a future goal is to monitor the electrochemical conversions more precisely or ultimately in situ by combining other spectroscopic techniques.

Spectroelectrochemistry, the future of visualizing electrode processes by hyphenating electrochemistry with spectroscopic techniques

“…The hyphenation of electrochemistry and microfluidics and lab-ona-chip systems is already well established. For a review regarding this subject the authors recommend to read the paper by Odijk et al 108 Although less established than electrochemistry, the combination of IR with microfluidics is also a developing field, for example: an ATR-IR device for the study of electric field-driven processes, 109 reaction monitoring 110 and the analysis of chemical reaction intermediates. 111 A recent review written on spectroscopic microreactors for heterogeneous catalysis by Rizkin et al also includes a section about IR.…”

Design of Electrochemical Microfluidic Detectors: A Review

“…[11] Many of the specific applications have been summarized in recent reviews, for example, microfluidic flow cells, [12][13][14] CO 2 electroreduction flow cells, [15] microfluidic biosensors, [4,16,17] and nanofluidic sensors and processors. [18][19][20] While attractive, the combination of several simultaneous processes puts a large demand on the experimenter, where an understanding of the flow pattern, current and potential distribution, and the reaction environment is necessary. As a consequence, microfluidic devices require optimization for specific applications.…”

“…The working electrode can be either 2D or 3D, it can be smaller or larger, and it can have several shapes, for example, round or straight like a channel electrode. The simplest electrode to use and manufacture is a planar electrode, [18] see example in Figure 1a. [27] While this is useful for many purposes, 3D electrodes are commonly used, for example, for detection of DNA markers, [28][29][30] see Figure 1b, or the use of electrode columns to increase the detection surface, [31] see Figure 1c.…”

In Situ Mapping of H2, O2, and H2O2 in Microreactors: A Parallel, Selective Multianalyte Detection Method

“…An area where electrochemical sensors are rarely used to date is applications concerning micro-process and reactor technology. While sensor integration and electrochemical sensing on the micro- and nanoscale have been reported, , we aim at integration in stainless steel reactors at elevated pressure. In principle, the advantages offered by these sensors should be well suited for such applications as they offer the ability to continuously determine the reactant concentration in a fast, precise, and marker-free way.…”