Cross-polarization scheme for fluorescence detection for biochip and biomedical applications

摘要

The trend in medical equipment is toward compact and integrated low cost medical test devices. Fluorescence-based assays are used to identify specific pathogens through the presence of dyes, but typically require specialized microscopes and narrow-band optical filters to extract information. We present a novel method of using polarizers in cross orientation with each other to filter out excitation light and allow detection of low signal levels of fluorescence with a simple intensity-based detector in the presence of high levels of excitation light. This concept is demonstrated using an inverted microscope fitted with a halogen lamp as the excitation source and an organic photovoltaic (PV) cell as the intensity detector. The excitation light is linearly polarized and used to illuminate a microfluidic device containing a 50 μl volume of Rhodamine 6G dye dissolved in water. The detector (with a second polarizer orientated perpendicularly to the first) is placed over the microfluidic device. The resulting emission signal was detected by the organic PV cell down to a concentration of 100 nM This suggests that an integrated microfluidic device, with a PV detector and an organic light emitting excitation source and integrated polarizers, could be fabricated to realize a economical 'lab on a chip' device for fluorescence assays.