Microchemistry- and MEMS-based Integrated Electrochemical Devices for Bioassay Applications

Abstract

Here, we present an overview of our recent research progress in development of electrochemical devices/systems for bioassays. These devices/systems are based on microchemistry and micro-electromechanical systems (MEMS) for sophisticated analytical and electrochemical measurements. In particular, we exploit the unique chemical reactions occurring in micrometer-size spaces and/or involving micrometer-size structures for bioassays, including cell analyses. This paper addresses five topics: probe-, chip-, large-scale-integration chip-, and dielectrophoresisbased devices, and electrodeposition of hydrogels for bioassays.

Electrochemical Biosensing System for Single Cells, Cellular Aggregates and Microenvironments

“…Especially, electrochemical characterizations of the cellular status embryos, ESCs, and other cellular aggregates were vigorously carried out by our group. [17][18][19][20][120][121][122][123][124] The developmental and differentiation potentials of the cellular aggregates were predicted by electrochemical measurements based on the respiratory and/or alkaline phosphatase activities in several specific situations. The respiratory characterization of cellular aggregate has been carried out for rat primary hepatocytes, 125 mesenchymal stem cells 95 and skeletal muscle cells incorporated in hydrogel containing metallic glass wire materials.…”

“…5,16 For non-scanning electrochemical bio-devices, electrode arrays can be integrated on a cellular chip for high-throughput real time monitoring of biological functions. [17][18][19][20][21][22] Previously, we have reviewed progress of whole-cell biosensors, especially incorporation of microfabrication technologies and genemodified engineering. 23 Originally, a cell-based sensor meant an electrode immobilized with whole-cells instead of purified enzymes.…”

Unconventional Electrochemistry in Micro-/Nanofluidic Systems

“…One of the main challenges in creating micro- and nanodevices for chemical analysis is downscaling the measurement system that is ultimately used for readout. Several features of electrochemistry render it a desirable mechanism for transducing chemical information into electrical signals [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]: The fabrication of electrodes suitable for electrochemistry is largely compatible with the methods employed for creating micro- and nanofluidic channels, it requires minimal additional (relatively low-cost) equipment, its sensitivity often increases with the downscaling of the electrode dimensions, it directly yields electrical signals without an intermediary transduction step (e.g., light), and it operates at relatively low power. Nonetheless, electrochemical methods can prove challenging to implement in micro- and nanosystems: While the concepts and instrumentation required for such measurements are well developed on the macroscopic scale, subtle, unobvious adjustments and compromises are often necessary upon downscaling.…”