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

An electrochemiluminescence (ECL) detector and a microenzymatic reactor (ME R) combining Si and SU-8 technologies are described. Both devices were fabr icated using standard processing techniques to produce on-wafer sensor elem ents, which were composed of a platinum or, alternatively, carbon interdigi tated electrode array. The platinum array was resting on top of an Si pn ph otodiode. After these elements were completed, the entire wafer was modifie d with SU-8, which was structured to form a series of shaped spacers surrou nding each device. For the ECL detector, a simple flow-channel was defined whereas for the microreactor a more complex layout defining two chambers se parated by a series of SU-8 columns was employed. The upstream chamber of t he microreactor was packed with porous glass beads modified with immobilise d enzyme glucose oxidase whereas the downstream chamber contained the elect rochemical detector. The performance of the ECL detector was assessed by the detection of codein e using ruthenium (II) tris(2,2'-bipyridyl). A detection limit of 100 mu M 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 de tection limits of 2 and 50 mu M by electrochemistry and ECL, respectively. This system was found to have a lifetime of at least 1 month when stored at 4 degrees C. (C) 2000 Elsevier Science S.A. All rights reserved.