No abstract

An array of up to 5 LEDs is presented to optimize the excitation signal that is transferred into a fluorescence analysis system. The array is varied by both type and drive current in order to broadly and narrowly tune the aggregate spectrum generated by the LED array to more closely match the desired excitation spectrum. Optimization results are shown for (a) a theoretical desired spectrum that clearly shows the increased flexibility of the LED array; (b) an experiment with AM1 bacteria demonstrating comparable emission output between a conventional Xenon lamp and an over driven LED array; and (c) an experiment with Rhodamine G that shows over a two-fold improvement in signal to noise ratio (or emission) obtainable using an optimized array over a non-optimized array. The flexibility of the LED array offers up to 3.2 million possibilities for aggregate spectra; without overdrive conditions, the 5-element array can only be configured into a maximum of 1020 different aggregate spectra.

Initial results of a comprehensive design software that optimizes parameters for fluorescence analysis of a user-defined fluorophore are presented. SLAP (spectral LED aggregation program) automatically selects configurations of LEDs that, in a fluorescence analysis system, maximize the emission signal (useful output) as a function of the excitation signal (interference), optics, photodetection modality, and sample characteristics. Initial results draw on an extensive database of blue, blue-green, green and purple LEDs characterized across a range of nominal and overdrive operating conditions. Overdrive conditions enable spectral shifts of the LED excitation bands to enhance the overall flexibility of SLAP optimization. Representative results show a 70.1% improvement in collected signal for GFPuv fluorophores when compared to conventional LED-based fluorescence operated under nominal operating conditions.