title: On-chip contactless four-electrode conductivity detection for capillary electrophoresis devices.
abstract: In this contribution, a capillary electrophoresis microdevice with an integrated on-chip contactless four-electrode conductivity detector is presented. A 6-cm-long, 70-microm-wide, and 20-microm-deep channel was etched in a glass substrate that was bonded to a second glass substrate in order to form a sealed channel. Four contactless electrodes (metal electrodes covered by 30-nm silicon carbide) were deposited and patterned on the second glass substrate for on-chip conductivity detection. Contactless conductivity detection was performed in either a two- or a four-electrode configuration. Experimental results confirmed the improved characteristics of the four-electrode configuration over the classical two-electrode detection setup. The four-electrode configuration allows for sensitive detection for varying carrier-electrolyte background conductivity without the need for adjustment of the measurement frequency. Reproducible electrophoretic separations of three inorganic cations (K+, Na+, Li+) and six organic acids are presented. Detection as low as 5 microM for potassium was demonstrated.
authors.affiliation: Electronic Instrumentation Laboratory-DIMES, Department of Microelectronics, Delft University of Technology, Delft, The Netherlands. F.Laugere@its.tudelft.nl
authors.forename: Frederic
authors.initials: F
authors.lastname: Laugere
authors.forename: Rosanne M
authors.initials: RM
authors.lastname: Guijt
authors.forename: Jeroen
authors.initials: J
authors.lastname: Bastemeijer
authors.forename: Gert
authors.initials: G
authors.lastname: van der Steen
authors.forename: Axel
authors.initials: A
authors.lastname: Berthold
authors.forename: Erik
authors.initials: E
authors.lastname: Baltussen
authors.forename: Pascalina
authors.initials: P
authors.lastname: Sarro
authors.forename: Gijs W K
authors.initials: GW
authors.lastname: van Dedem
authors.forename: Michiel
authors.initials: M
authors.lastname: Vellekoop
authors.forename: Andre
authors.initials: A
authors.lastname: Bosschet