On-chip contactless four-electrode conductivity detection for capillary electrophoresis devices.
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.
Laugere
Frederic
F
Electronic Instrumentation Laboratory-DIMES, Department of Microelectronics, Delft University of Technology, Delft, The Netherlands. F.Laugere@its.tudelft.nl
Guijt
Rosanne M
RM
Bastemeijer
Jeroen
J
van der Steen
Gert
G
Berthold
Axel
A
Baltussen
Erik
E
Sarro
Pascalina
P
van Dedem
Gijs W K
GW
Vellekoop
Michiel
M
Bosschet
Andre
A