Towards a fully integrated laser-induced fluorescence detection device for point-of-care bioanalysis

We have reduced laser light scattering in an integrated hydrogenated amorphous Si (a-Si:H) fluorescence detector, significantly improving a limit-of-detection (LOD). The detection platform comprises a microlens and the annular fluorescence detector where a thick SiO₂/Ta₂O₅ multilayer optical interference filter is monolithically integrated on an a-Si:H pin photodiode. With a microfluidic capillary electrophoresis (CE) device mounted on the platform, the integrated system is demonstrated to separate DNA restriction fragment digests with high speed, high sensitivity and high separation efficiency, implying single molecular DNA detection when combined with polymerase chain reaction (PCR). Furthermore, we have constructed a palmtop laser-induced fluorescence detection (LIF) module that is comprised of an InGaN laser diode, micro-lenses and the integrated fluorescence detector.