Patent Application Titled "Systems and Methods for Individually Trapping Particles from Air and Measuring the
The assignee for this patent application is
Reporters obtained the following quote from the background information supplied by the inventors: "Embodiments of the present invention are generally directed to measuring optical spectra of other properties of airborne particles that can be used for detection or characterization of particles in air, including harmful biological and chemical particles in air.
"Airborne particles pose many problems. They can impact human health, agriculture, and the earth's climate. Pollens and fungal spores can cause allergies such as hay fever. Asthma can be exacerbated by airborne particles such as pollens and pollen fragments, particles from fungi, including fungal spores, bacteria, proteins from cats and dogs, and particles from cockroaches, and dust mites. Airborne particles, primarily bacteria and viruses, but also some fungi, are a primary means of disease transmission in humans and other animals. Fungal spores and bacteria transmit diseases of agricultural crops that are responsible for tremendous losses each year.
"Primary Biological Aerosol Particles (PBAP) include bacteria, fungi, pollens, viruses, algae, protein allergens from cats and other animals, bits of leaves, plants, skin, dandruff, etc. These particles may be aerosolized by airflows, abrasion, and by injection (e.g., sneezing by animals or expulsion of spores by fungi). In addition to these commonly-identified particles, the PBAP may also include fragments of those particles, e.g., micron-sized particles that form when pollen grains undergo osmotic shock and rupture within the anthers or catkins of anemophilous plants may later be released into the air to form a respirable, antigen laden aerosol. Similarly, allergen-laden fungal fragments can be much smaller than the fungal spores. PBAP also includes re-aerosolized materials. Plants, fungi, and some animals have evolved efficient mechanisms to inject their pollens, spores, or their offspring, etc., into the air.
"There are large differences in the estimates of both PBAP emissions into the atmosphere and atmospheric loadings. PBAP has been reported to contribute as much as 25% of the total mass of atmospheric particulate matter. Fluorescent biological aerosol particles were found to contribute 28% of the total particle number (in the 0.8-20-mm diameter range) above a forest canopy in
"FIG. 1 is a schematic illustration of some sources of atmospheric aerosols and their chemical and photochemical transformations. An atmospheric aerosol 10 can be extremely complex. Biological particles found in the atmosphere may include organisms such as bacteria, fungal spores, viruses, pollens, fragments of plants, fungi, etc. Complex mixtures can occur in particles because of (a) emission of complex particles, (b) adsorption of gasses by particles, © agglomeration of particles, (d) chemical and photochemical reactions of particles, and (e) cycling of particles through clouds. Sunlight provides the energy necessary for many chemical reactions in particles. Long range transport occurs over thousands of miles, such as for example, from
"Many particles in the atmosphere are complex mixtures. These result from emissions of complex particles, and adsorption, agglomeration, chemical reactions which can occur, especially in cycling though clouds. Sunlight provides the energy for many atmospheric chemical reactions affecting particle composition. Bacteria, pollens and other PBAP can also act as cloud condensation nuclei, and thereby affect rain deposition patterns, cloud coverage, and global climate. Also, many PBAP, including many pollen and fungal particles, and other carbon-containing aerosols (e.g., soot) absorb atmospheric radiation and re-emit some of that radiation at ultraviolet and visible wavelengths. Therefore, the absorption and fluorescence properties of atmospheric pollen and fungal materials are relevant for understanding their effects on climate. Some of the, if not the, largest uncertainties in global climate models are attributable to the uncertainties regarding the effects of aerosols. Some aerosols (e.g., soot) can contribute to warming by absorbing light. Other aerosols (composed of, e.g., bacteria, silica dust, or ammonium sulfate) can contribute to cooling by scattering light or by acting as cloud condensation nuclei which help generate cloud droplets which also scatter light, preventing sunlight from reaching the earth.
"Optical trapping and manipulation of micron-sized particles, nanoparticles, molecules, and atoms have been used in aerosol science, chemistry, physics, biology, and interdisciplinary studies. For example, in one type of radiation pressure trap, commonly referred to as optical tweezers, a tightly-focused beam is used to hold particles. Other optical trapping methods have also been reported, e.g., using longitudinal trapping, holographic methods, self-reconstructing beams, and axicon(s). Combinations of trapping with other analytical techniques, e.g., Raman spectroscopy of particles in air or in liquid, provide ways to analyze molecular composition and to study time-varying phenomena, e.g., dynamic reactions in individual living cells.
"Methods and devices exist for counting and characterizing airborne pollens, fungal and plant spores, bacteria, protein allergens, and other PBAP.
"These techniques, however, are not without drawbacks. For example, airborne biological agents, such as anthrax or plague, can be dispersed at such low concentrations that no one would suspect a release until after persons got sick and went to the doctor. Although, forecasts related to allergens are available in much of the world, counting and classifying pollens to the genus or species level is presently performed by labor-intensive microscopic analysis of collected samples. At present, it is prohibitively expensive to measure bacteria, protein toxins or allergens, pollen and fungal spores with sufficient spatial and temporal resolution and specificity to provide adequate warning of a bioagent attack, or to provide adequate forecasts for persons with allergies. The times required for sampling and analyzing airborne bacteria, pollen and fungal particles preclude real-time alerts of hazardous conditions, and they make more difficult potential studies of the effects of bacteria, pollens or fungal particles on atmospheric processes, or studies of transmission of fungal diseases of plants.
"Improved, automated, and near-real-time techniques for characterizing bacteria, pollens, fungal spores, and other PBAP may be useful."
In addition to obtaining background information on this patent application, NewsRx editors also obtained the inventors' summary information for this patent application: "Embodiments of the present invention are directed to systems and methods for sampling atmospheric particles by trapping particles from air and measuring the optical spectra and/or other properties of (typically) individual trapped particles.
"According to one embodiment, a system for continuously sampling particles from air may include: an airflow system configured to continuously draw air including airborne particles into the system; a photophoretic trap that uses photophoretic forces of a laser beam to trap one or more of the airborne particles from the drawn air; a measurement device configured to measure one or more properties of the trapped one or more airborne particles; and a controller configured to repeatedly trap, measure and release one or more airborne particles.
"According to another embodiment, a method for continuously sampling particles from air may include: continuously directing air including airborne particles toward a photophoretic trap that uses photophoretic forces of a laser beam to trap one or more of the airborne particles; detecting an airborne particle in the air approaching and/or within the photophoretic trap; trapping one or more airborne particles in the photophoretic trap; measuring one or more properties of the trapped one or more airborne particles; and releasing the trapped one or more airborne particles.
"These and other embodiments of the invention are described in more detail, below.
BRIEF DESCRIPTION OF THE DRAWINGS
"So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments, including less effective but also less expensive embodiments which for some applications may be preferred when funds are limited. These embodiments are intended to be included within the following description and protected by the accompanying claims.
"FIG. 1 is a schematic illustration of some sources of atmospheric aerosols and their chemical and photochemical transformations.
"FIG. 2 shows a schematic illustration of a system for continuously sampling particles from air according to an embodiment of the present invention.
"FIGS. 3A illustrates a schematic of a photophoretic trap which may be used in embodiments of the present invention.
"FIG. 3B is an illustration of an experimental photophoretic trap which may be used in embodiments of the present invention.
"FIG. 4 shows a schematic of a photophoretic trap which may be used in embodiments of the present invention.
"FIG. 5 illustrates exemplary Raman spectra of various substances.
"FIG. 6 illustrates exemplary Raman spectra of various substances.
"FIG. 7 shows one configuration of collection optics which may be used in embodiments of the present invention.
"FIG. 8 illustrates the logic for the controller according to one embodiment of the present invention.
"FIG. 9 illustrates a schematic of the air sampling and particle trapping part of a single particle Raman spectrometer system according to an embodiment of the present invention.
"FIG. 10 illustrates a schematic of a photophoretic trap and trigger beams with detectors according to an embodiment of the present invention.
"FIG. 11 illustrates photophoretic trapping and Raman measurement sub-systems for continuously sampling particles from air according to embodiments of the present invention.
"FIG. 12 illustrates photophoretic trapping and Raman measurement sub-systems for continuously sampling particles from air according to embodiments of the present invention.
"FIG. 13 illustrates the light intensity distribution for one of the conical beams, shown in a plane transverse to the axis of the conical beams of the system illustrated in FIG. 10.
"FIG. 14 shows photographs of single particles trapped in air.
"FIGS. 15A-C show the Raman scattering signal of a particle measured using different data acquisition conditions. More particularly,
"FIG. 15A shows the Raman scattering signal of a particle measured using data acquisition conditions extending over a 30 second interval, slit width 500 .mu.m; and Gain=2 for the EMCCD.
"FIG. 15B shows the Raman scattering signal of a particle measured using data acquisition conditions extending over a 30 second interval; slit width 100 .mu.m; and Gain=5 for the EMCCD.
"FIG. 15C shows the Raman scattering signal of a particle measured using data acquisition conditions extending over a 1/2 second time interval; slit width 500 .mu.m; and Gain=100 for the EMCCD."
For more information, see this patent application: Hill,
Keywords for this news article include: Antigens, Pollen, Viruses, Bacteria, Virology, Allergens, Immunology, Fungal Spores, Climate Change, Flowering Tops, Global Climate, Global Warming, Plant Germ Cells, Plant Structures,
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