Integrated multi-wavelength fluorescence sensors

Significant efforts have been made to implement capabilities of a laboratory system into a compact portable fluorometer composed of solid-state components, such as light emitting diodes (LEDs) and photodiode (PDs). These devices, still use statistical sampling, lenses and glass filters, and do not meet the requirements addressed for multi-functional fluorescence sensors capable of performing in super-ambient environments. We have shown that UV/blue GaN/InGaN-based LEDs and optically filtered Si PDs can be employed in compact optoelectronic sensors capable of multi-functional operation in the absorption, scattering, and fluorescence mode. To take advantage of the high temperature and chemical stability of the III nitrides it would be beneficial to use these materials for the fabrication of all sensor components including the wavelength-selective features. In this work we fabricated a multi-wavelength fluorescence sensor prototype using III nitride-based component's. This device was tested for measurements of fluorescein, chlorophyll, aromatic hydrocarbons, and E.coli bacteria expressing various fluorescence proteins. The new sensor prototype exhibited a lower detection limit and a larger dynamic range, than those achieved with previous prototypes. It has a compact size and a low fabrication cost.