Filterless fluorometry with enhanced sensitivity.

We describe a novel approach for fluorometry with light-emitting-diodes (LEDs) as excitation source that capitalizes on the principle of light shielding and total internal reflection to operate without optical filters. This scheme is practicable, demonstrated to significantly reduce the amount of excitation light overlapping the fluorescence signals at the photodetector, operated best with excitation light applied orthogonal to detection, and permitted higher measurement sensitivity of fluorophore emission.