Plastic particle detector for detection of biological aerosol and other fluorescent materials
Inventors
Goad, Aime P. • Sickenberger, David W. • Narayanan, Fiona E. • Kreis, Richard J. • Strauch, III, Lester D. • Kilper, Gary K. • Cabalo, Jerry B. • Wylie, Harold S. • Wong, Anna
Assignees
United States Department of the Army • Government of the United States of America
Publication Number
US-9500591-B1
Publication Date
2016-11-22
Expiration Date
2035-04-03
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Abstract
A plastic particle detector for detecting biological and other fluorescent materials is disclosed. The detector detects the fluorescence and scattering signals from these materials using deep UV excitation. The detector is fabricated using plastic materials and exploits the properties of lower manufacturing costs, lower materials costs, light weight, ruggedness and assembly ease offered by plastics, while eliminating stray fluorescence signals ordinarily generated by plastic materials.
Core Innovation
The invention disclosed is a plastic particle detector for detecting biological and other fluorescent materials using deep UV excitation. The detector utilizes plastic materials for its fabrication, taking advantage of the benefits plastics offer such as lower manufacturing and material costs, light weight, ruggedness, and ease of assembly. Importantly, the plastic used in the detector is chosen or configured to eliminate stray fluorescence signals that are typically generated by plastic materials when exposed to UV light.
The particle detector is comprised of three main regions: an excitation region with a plastic housing that holds the excitation source generating light to excite particles passing through the detector, an interrogation region with a second plastic housing where an emission beam is produced from particles excited by the light, and a detection region containing a third plastic housing and optical detectors that determine the scattering and fluorescence properties of the particles. These plastic housings are injection molded from uncoated plastics that do not interact with the excitation light to produce interfering fluorescence or scattering signals, exemplified by polyamide 66 resin with glass and carbon black fill.
The background explains that UV-induced fluorescence is a promising method for real-time detection of biological agents, but prior art detectors avoid using uncoated plastics in their optical trains due to significant autofluorescence and scattering from plastics, which interfere with detection. Metals and coated parts have been used instead, but plastics offer significant advantages in cost, weight, ruggedness, and assembly efficiency. The invention addresses the longstanding problem of plastics’ autofluorescence and reflectivity in the deep UV range, enabling the use of plastics in an integrated particle detector optical train without compromising detection capabilities.
Claims Coverage
The patent includes multiple independent claims covering the plastic particle detector apparatus, its construction, and manufacturing method. The claims describe inventive features related to plastic housings, excitation and detection regions, optical components, and assembly methods.
Plastic housings with specific material composition
The detector comprises three plastic housings—the excitation region housing, the interrogation region housing, and the detection region housing—formed from an uncoated polyamide 66 resin with glass and carbon black fill that do not produce detectable fluorescence or scattering when exposed to excitation light.
Integrated excitation, interrogation, and detection regions with molded optical structures
The excitation region contains molded structures holding an excitation source and optical devices such as lenses and filters to focus light; the interrogation region includes a cavity for particle excitation and a beam dump; the detection region includes molded structures to hold optical detectors configured to separately detect scattering and fluorescence signals from particles.
Injection molding and embedded fasteners for assembly without additional hardware
The plastic housings are injection-molded and include embedded fasteners and features such as pins, slots, catches, and tabs that allow the detector to be assembled without glue, welding, or extra hardware, reducing assembly complexity and cost.
Optical detection setup with beam splitter and filters
The detection region incorporates a beam splitter that splits the emission beam into two portions for respective optical detectors, one to detect radiation scattering properties and the other to detect fluorescence properties of particles, using photomultipliers or avalanche photodiodes as optical detectors.
Excitation source operating in deep UV wavelength range
The excitation source generates deep UV light (e.g., around 266 nm), necessary to excite fluorescence from biological aerosol particles, and the associated excitation, interrogation, and detection components are designed to handle this excitation range effectively with minimal stray signals.
Method of manufacturing plastic particle detector
The method claims cover forming the first, second, and third plastic housings with molded structures for holding the excitation source, optical devices, and detectors respectively, using polyamide 66 resin with glass and carbon black fill, incorporating embedded fasteners to enable assembly without additional hardware.
Collectively, the claims cover a particle detector made from specific uncoated plastic materials that minimize autofluorescence and scattering, incorporating integrated molded features for excitation, particle interrogation, and detection regions, and enabling simplified, hardware-free assembly. This innovation enables effective deep UV fluorescence and scattering detection of aerosol particles with plastics, overcoming prior art limitations.
Stated Advantages
Lower manufacturing and material costs due to use of plastic rather than metals or coated parts.
Reduced weight and improved ruggedness enhancing portability and durability of the detector.
Ease of assembly enabled by injection molding and embedded fasteners, eliminating need for additional hardware, glue, or welding.
Reduced number of parts needed as optics can be held directly by molded plastic features, decreasing potential for misalignment and loosening.
Lower stray light, fluorescence, and scattering signals from the plastic housings improve detection sensitivity, enabling detection of submicron biological aerosol particles.
Documented Applications
Real-time detection of aerosolized biological agents and other fluorescent materials using UV-induced fluorescence and scattering signals.
Biological agent warning sensor applications analogous to prior art sensors such as BAWS.
Any optical system requiring reduction of stray optical background signals, including telescopes, microscopes, binoculars, fluorometers, atomic emission spectrometers, Raman spectrometers, optical scanners, and optical readers.
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