Amperometric PDMS/glass capillary electrophoresis-based biosensor microchip for catechol and dopamine detection

A new microfabricated lab-on-chip device with a fully integrated electrochemical (EC) detection system has been developed. In this biochip set-up, all the detector electrodes as well as the high-voltage separation electrodes are incorporated directly onto a glass substrate via traditional microfabrication techniques (photolithography, wet-chemical etching, electron-beam evaporation, lift-off). The lab-on-chip device includes a top PDMS plate containing the separation and injection channels for capillary electrophoresis (CE). This CE/EC device has no more external electrodes. The electrodes’ geometry, their position and the thickness of the deposited metal layers were established by photolithographical patterning. This biosensor chip has been used to detect dopamine and catechol, two important catecholamines with total running times of less than 90 s. For both catecholamines, the dependence of the current signal on the concentration was showing a good linearity in the range from 20 to 100 μM, with a sensitivity of 16.1 pA/μM for dopamine and to 2.7 pA/μM for catechol, and detection limits of 2 μM dopamine and 8 μM catechol.