Palladium film decoupler for amperometric detection in electrophoresis chips

Demonstrated in this article is that a palladium metal film can be applied to decouple the electric circuitry of electrochemical detection from that of the electrophoretic separation in an electrophoresis chip. The Pd solid-state field decoupler, as well as the working electrodes, is thermally evaporated onto the plastic chip and oriented vertically across the separation channel. After the sample zones flow over the Pd decoupler, their electrochemical response is measured at working electrodes in the downstream pathway. Because the electrodes are on the separation channel, the electrode channel 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 level at the working electrode is < 15 pA at an electric field of 570 V/cm.