Microreactor and electrochemical detectors fabricated using Si and EPON SU-8

Abstract

An electrochemiluminescence (ECL) detector and a microenzymatic reactor (MER) combining Si and SU-8 technologies are described. Both devices were fabricated using standard processing techniques to produce on-wafer sensor elements, which were composed of a platinum or, alternatively, carbon interdigitated electrode array. The platinum array was resting on top of an Si pn photodiode. After these elements were completed, the entire wafer was modified with SU-8, which was structured to form a series of shaped spacers surrounding each device. For the ECL detector, a simple flow-channel was defined whereas for the microreactor a more complex layout defining two chambers separated by a series of SU-8 columns was employed. The upstream chamber of the microreactor was packed with porous glass beads modified with immobilised enzyme glucose oxidase whereas the downstream chamber contained the electrochemical detector. The performance of the ECL detector was assessed by the detection of codeine using ruthenium (II) tris(2,2′-bipyridyl). A detection limit of 100 μM was obtained and pharmaceutical preparations were successfully assayed. The MER was first evaluated by electrochemical determination of glucose and as a next step, a miniature ECL detector was placed on line downstream the MER to perform glucose measurements by ECL. Glucose was determined with detection limits of 2 and 50 μM by electrochemistry and ECL, respectively. This system was found to have a lifetime of at least 1 month when stored at 4°C.