Optoelectronic detection of DNA molecules using an amorphous silicon photodetector

摘要

This work demonstrates the use of an amorphous silicon (a-Si:H) photodetector to measure the density of covalently-bound DNA molecules tagged with a fluorescent molecule. This device is based on the photoconductivity of a-Si:H in a coplanar electrode configuration. Excitation of a fluorescently-tagged biomolecule with near UV/blue light results in the emission of visible light. The emitted light is then converted into an electrical signal in the photodetector, thus allowing the detection of the presence of the tagged DNA molecules. The design, fabrication and characterization of this integrated a-Si:H-based bio-detector is described. The detection limit of the present device is of the order of 20 pmol/cm~2. A surface density of ≤ 30 pmol/cm~2 for DNA covalently-bound to an active silica layer was measured with the a-Si:H-based bio-detector.