Integration of "on-chip" electrochemical detection in a microfabricated capillary electrophoresis device

• Published in: Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology Vol. 2; pp. 1640 - 1641 vol.2
• Main Authors: Roussel, T.J., Crain, M.M., Bathlagundu, V., Jackson, D.J., Conklin, J.A., Pai, R., Naber, J.F., Walsh, K.M., Gullapalli, J., Baldwin, R.P., Keynton, R.S.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2002
• Subjects: Bonding; Chemicals; Electrodes; Electrokinetics; Etching; Glass; Microchannel; Performance analysis; Platinum; Prototypes
• DOI: 10.1109/IEMBS.2002.1106578
• ISBN: 0780376129; 9780780376120
• ISSN: 1094-687X

Our efforts have been focused on developing a self-contained and transportable capillary electrophoresis (CE) system with integrated electrochemical detection (ECD). The current prototype includes all necessary electrodes "on-chip" and utilizes miniaturized CE and ECD supporting electronics custom designed for this purpose. A novel microfabrication procedure was used to create recessed platinum electrodes and the CE/EC device from two patterned ultra-flat glass substrates. The electrodes in the bottom substrate were formed by a self-aligned etch and deposition technique followed by a photolithographic lift-off process. The microchannels (20 /spl mu/m deep/spl times/50 /spl mu/m wide [avg]) were chemically etched into the top substrate followed by thermal bonding to complete the microchip device. CE/EC experiments were performed using 0.02M phosphate buffer (pH 6), an analyte/buffer solution (2.2 mM dopamine, 2.3 mM catechol) and varying separation voltages (0-250 V) with a custom electronics unit interfaced to a laptop computer for data acquisition. Detection limits (S/N=3) were found to be 4.3 /spl mu/M for dopamine and 4.4 /spl mu/M for catechol. A linear detection response was observed up to 2200 /spl mu/M and 2300 /spl mu/M for dopamine and catechol, respectively.