We demonstrate a compact system incorporating a 32-element linear array of ultraviolet (UV) light-emitting
diodes (LEDs) to the in-flight fluorescence detection of aerosolized particles. Custom electronics manage a standalone
system and enable real-time processing of spectral data, which is used to cue a miniaturized aerodynamic deflector for
physical particle separation. This front-end system improves the prospects for many second-stage analysis methods by
reducing the background particle burden and providing a suspicious-particle enriched sample. The performance of UV
LED arrays as an excitation source is established by the ability to detect emission from NADH and tryptophan in aerosol
samples. On-the-fly fluorescence collection, operation of a real-time spectral algorithm, and aerosol concentration is
demonstrated by separating particles that exhibit a specific spectral feature from a background of otherwise fluorescing
We demonstrate a compact system, incorporating a 32-element linear array of ultraviolet (290 nm and 340 nm) light-emitting diodes (LEDs) and a multi-anode photomultiplier tube, to the in-flight fluorescence detection of aerosolized particles, here containing the biological molecules tryptophan and NADH. This system illustrates substantial advances in the growth and fabrication of new semiconductor UV light emitting devices and an evolution in packaging details for LEDs tailored to the bio-aerosol warning problem.
We report on high output power from the quaternary AlGaInN multiple quantum well (MQW) ultraviolet light emitting diodes (UV LEDs) in the 340 nm and 280 nm wavelength range. The output power up to 1.5 mW from a 100 μm diameter device with bare-chip configuration was measured under room temperature cw operation. The internal quantum efficiency was estimated to be between 7 and 10%. In addition, the output power and external quantum efficiency for fully packaged 1x1mm<sup>2</sup> large area device were as high as 54.6 mW and 1.45%, respectively, at the injection current of 200 A/cm<sup>2</sup> under pulsed operation. The devices were incorporated into prototype system for fluorescence based bio-sensing. We also report the performance of 285 nm UV LEDs.