Detection of fluorescently labeled biomolecules immobilized on a detachable substrate using an integrated amorphous silicon photodetector

An integrated platform for biomolecular detection is described comprising two parts: (1) an $a\text{-Si}:\text{H}$ $p\text{-}i\text{-}n$ photodiode with an integrated filter for fluorescence detection, and (2) a detachable layer (a glass slide) where the biological molecular recognition reaction takes place. The distance between the photodetector and the layer with the fluorescently labeled biomolecules must be accurately controlled to ensure adequate sensitivity. A spacer $400\mu \text{m}$ thick was used to separate the photodetector from the molecular layer. The minimum surface density of quantum dot Evitag 604 nm detected was $8\text{fmol}/{\text{cm}}^2$. The detection of an antibody-antigen molecular recognition reaction is presented.