ON-CHIP GENERATION AND DETECTION OF ELECTROCHEMILUMINESCENCE

A miniaturized and fully integrated probe for analytical assays based on electrochemiluminescence (ECL) is proposed. It combines both, the e lectrode transducer and the photodetector in a single 5x6 mm(2) silico n chip. The device accommodates two identical cells, each consisting o f a gold interdigitated microelectrode array (IDA) resting on top of a pn photodiode, and of which one is used as an active cell and the oth er as a dummy. Light-intensity measurements are taken in a differentia l mode to increase the overall system performances. The device was cha racterized using ruthenium (II) tris(2,2'-bipyridyl) and tripropylamin e as model system. The influence of both, the pH and the electrode to electrode distance on the response was investigated. The highest signa l intensities were detected in a phosphate buffer solution of pH 7.5 a nd an IDA gap of 0.8 mu m. Excellent correlation was achieved between the peak light intensity and the concentration of the ruthenium comple x over a 0.5-50 mu M concentration range. (C) 1998 Elsevier Science B. V.