This paper presents a new method for obtaining highly efficient electrochemiluminescence (ECL) of tris(2,2'- bipyridine) ruthenium (TBR) in aqueous solutions and a biosensor which utilizes this method. An interdigitated, microelectrode array is employed with electrode widths and spacings of 5 micrometer. The microelectrode is supported on a silicon nitride coated silicon substrate and occupies 1 mm2. Each microelectrode is 1 mm long and 5 microns wide. The diffusion enhancement produced by the microelectrode geometry, the small electrode spacing and the electrode material are all critical parameters for high ECL efficiency. ECL has been detected from TBR concentrations as low as 1 (mu) M, using a silicon PIN photodiode detector at room temperature. For biosensing applications, TBR is attached to the molecule of interest and ECL is then generated at the electrode surfaces. Cell configuration and the results of preliminary studies of the detection of TBR labeled DNA, attached to paramagnetic beads are presented.
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