N. Kent

We report the development of enhanced optical platforms for fluorescence-based biosensors. A previous analysis by us has shown that the emission of fluorescence in such a system is highly anisotropic and is preferentially emitted into the substrate over a well-defined angular range, with the result that the light is guided along the substrate via total internal reflection. However, conventional optical biosensors based on fluorescence detection typically employ a detector that is positioned either directly above or directly below the biochip. As a consequence, only a small fraction of the total emitted fluorescence is detected, which impacts adversely on sensor performance. The enhanced biosensor presented here is based on a novel, generic platform specifically designed to overcome the inherent limitations of planar substrates. The platform incorporates custom-designed optical elements, the purpose of which is to redirect the emitted fluorescence onto a detector positioned beneath the biochip. Platforms were fabricated using the polymer processing technique of microinjection moulding. In this paper we demonstrate the ability of this optical system to achieve a 80-fold luminescence capture enhancement. We also demonstrate its effectiveness as an enhanced biosensor platform by carrying out a proof of principle BSA/antiBSA competitive assay. This work has significant implications for the development of mass-producible, highly efficient optical biosensors.