3D microelectrodes for coulometric screening in microfabricated lab-on-a-chip devices

This paper presents results indicating the complete oxidation of an analyte using a three-dimensional, large surface area microelectrode in a Lab-on-a-Chip (LOC) device. Traditional photolithographic fabrication techniques were used to construct the microchip prototype, with the exception of the 3D electrodes. Experiments were performed using a flow-injection scheme, where a 1 mM sample of catechol was directed towards the detection reservoir. Oxidation voltage at a planar upstream electrode was increased from 0 to 1.2 V in 0.1 volt increments and was shown to reduce the detection level of the sample at a downstream planar electrode (1.2 V). Oxidation voltage at the upstream 3D electrode was changed in a similar manner and was shown to completely eliminate detection at a downstream planar electrode. These results indicate the complete removal of sample from the flow stream, suggesting that 3D microfabricated electrodes could be used in an LOC device for coulometric screening.