Sensor-integrated fluorescent microarray for ultrahigh sensitivity direct-imaging bioassays: Role of a high rejection of excitation light

Fluorescent microarrays exploit fluorescent labeled targets bound to immobilized biomolecular probes. Their signal-to-noise ratio is limited by the collection aperture in common confocal geometries. Taking advantage of a very high rejection filter deposited onto a silicon arrayed detector (coupled-charge device or complementary metal-oxide semiconductor), it is demonstrated that a highly compact lens-free assay with photon collection of order unity operates with a 30-fold improvement over a conventional (substrate + free-space optics) scheme. Through analysis of improvements over the present demonstrator, a single molecule per pixel sensitivity is predicted.