Demonstrated in this article is that a palladium metal film can be applied
to decouple the electric circuitry of electrochemical detection from that o
f the electrophoretic separation in an electrophoresis chip. The Pd solid-s
tate field decoupler, as well as the working electrodes, is thermally evapo
rated onto the plastic chip and oriented vertically across the separation c
hannel. After the sample zones flow over the Pd decoupler, their electroche
mical response is measured at working electrodes in the downstream pathway.
Because the electrodes are on the separation channel, the electrode channe
l alignment is no longer a problem. For a separation channel of roughly 200
mum in width and 75 mum in depth in 10 mM phosphate (pH 5.1), the noise le
vel at the working electrode is < 15 pA at an electric field of 570 V/cm.