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Article

Fully Integrated On-Chip Electrochemical Detection for Capillary Electrophoresis in a Microfabricated Device

Richard P. Baldwin,*^§ Thomas J. Roussel, Jr.,^† Mark M. Crain,^‡ Vijay Bathlagunda,^‡ Douglas J. Jackson,^‡ Jayadeep Gullapalli,^§ John A. Conklin,^‡ Rekha Pai,^‡ John F. Naber,^‡ Kevin M. Walsh,^‡ and Robert S. Keynton^†

Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, Department of Mechanical Engineering, University of Louisville, Louisville, Kentucky 40292 and Department of Electrical and Computer Engineering, University of Louisville, Louisville, Kentucky 40292

Anal. Chem., 2002, 74 (15), pp 3690–3697

DOI: 10.1021/ac011188n

Publication Date (Web): June 27, 2002

Fax: (502) 852-8149. E-mail address: rick.baldwin@louisville.edu.

Department of Chemistry.

†

Department of Mechanical Engineering.

‡

Department of Electrical and Computer Engineering.

Abstract

Microfabricated lab-on-a-chip devices employing a fully integrated electrochemical (EC) detection system have been developed and evaluated. Both capillary electrophoresis (CE) channels and all CE/EC electrodes were incorporated directly onto glass substrates via traditional microfabrication techniques, including photolithographic patterning, wet chemical etching, DC sputtering, and thermal wafer bonding. Unlike analogous CE/EC devices previously reported, no external electrodes were required, and critical electrode characteristics, including size, shape, and placement on the microchip, were established absolutely by the photolithography process. For the model analytes dopamine and catechol, detection limits in the 4−5 μM range (200 amol injected) were obtained with the Pt EC electrodes employed here, and devices gave stable analytical performance over months of usage.