Integration of microchip electrophoresis with electrochemical detection using an epoxy‐based molding method to embed multiple electrode materials

Abstract

This paper describes the use of epoxy-encapsulated electrodes to integrate microchip-based electrophoresis with electrochemical detection. Devices with various electrode combinations can easily be developed. This includes a palladium decoupler with a downstream working electrode material of either gold, mercury/gold, platinum, glassy carbon, or a carbon fiber bundle. Additional device components such as the platinum wires for the electrophoresis separation and the counter electrode for detection can also be integrated into the epoxy base. The effect of the decoupler configuration was studied in terms of the separation performance, detector noise, and the ability to analyze samples of a high ionic strength. The ability of both glassy carbon and carbon fiber bundle electrodes to analyze a complex mixture was demonstrated. It was also shown that a PDMS-based valving microchip can be used along with the epoxy embedded electrodes to integrate microdialysis sampling with microchip electrophoresis and electrochemical detection, with the microdialysis tubing also being embedded in the epoxy substrate. This approach enables one to vary the detection electrode material as desired in a manner where the electrodes can be polished and modified in a similar fashion to electrochemical flow cells used in liquid chromatography.

Fast and versatile fabrication of PMMA microchip electrophoretic devices by laser engraving

“…Most importantly, this approach was implemented to avoid the formation of bubbles on the electrode surface and reduce the noise level of the analysis caused by the interference of the electrophoretic current on the detection circuit. In accordance to previous reports [55][56][57], the decoupler was placed 200 µm away from the detection electrode, as a balance between noise reduction and diffusion. This distance was also considered optimal as it minimized the deformation of the substrate between the decoupler and the waste reservoir (also cut through) and results in consistent data after re-alignment of the PMMA layer during the fabrication process (that also requires engraving the channels).…”

Real-Time Monitoring of Cellular Bioenergetics with a Multianalyte Screen-Printed Electrode

“…5 The addition of a sensor for cathecol further improved these measurements by allowing simultaneous detection of multiple analytes, which can provide a more detailed investigation of the biological system under study. 15 …”

Fast and versatile fabrication of PMMA microchip electrophoretic devices by laser engraving

“…Most importantly, this approach was implemented to avoid the formation of bubbles on the electrode surface and reduce the noise level of the analysis caused by the interference of the electrophoretic current on the detection circuit. In accordance to previous reports [55–57], the decoupler was placed 200 µm away from the detection electrode, as a balance between noise reduction and diffusion. This distance was also considered optimal as it minimized the deformation of the substrate between the decoupler and the waste reservoir (also cut through) and results in consistent data after re-alignment of the PMMA layer during the fabrication process (that also requires engraving the channels).…”