UV photodiode based portable fiber optic biosensor

The strong optical absorbance characteristics around 280 nm of several protein chromophores present in biomolecules like Immunoglobulin (IgG) and cell walls of bacteria can be exploited for direct detection of such biological analytes. In this report, we describe the development of a portable fiber optic biosensor, using a UV LED with peak emission at 280 nm and a UV photodiode to measure evanescent wave absorbance changes. A transimpedance amplifier is used as a (photo) current to voltage converter and for amplification of optical signals from the photodiode. The sensor is able to detect 50 μg/ml of Goat anti-Human Immunoglobulin (GaHIgG), used as a model protein and thus, could provide a suitable, inexpensive platform for label-free detection of water borne pathogen like E. coli cells.