Pathogen detection by simultaneous size/fluorescence measurement

Abstract

A method and apparatus for detecting pathogens and particles in a fluid in which particle size and intrinsic fluorescence of a simple particle is determined.

1 . A method of differentiating biological particles from inert particles in a fluid which comprises simultaneously measuring a particle size and detecting intrinsic fluorescence from that particle. 
     
     
         2 . The method of  claim 1 , wherein fluorescence intensity is measured and assigned a value, and including the step of classifying the particle as either inert or biological based on particle size and fluorescence intensity. 
     
     
         3 . The method of  claim 2 , wherein size information of the particle is used to classify whether that particle is a microorganism. 
     
     
         4 . The method of  claim 3 , wherein size information of the particle is derived from determining cross-section area of the particle, or volume of the particle. 
     
     
         5 . The method of  claim 4 , wherein volume of the particle is derived by first determining the diameter of the particle, and calculating its volume based on said diameter. 
     
     
         6 . The method of  claim 2 , wherein particle size and fluorescence intensity data from an individual particle is used to differentiate between pollen and allergens from microbes. 
     
     
         7 . The method of  claim 2 , wherein particle size and fluorescence signal data from an individual particle is used to estimate relative abundance of biochemical compounds inside the biological particles. 
     
     
         8 . The method of  claim 2 , wherein particle size and fluorescence intensity value from an individual particle is normalized by its size or volume and used to differentiate between inert particles from microbes. 
     
     
         9 . The method of  claim 2 , wherein particle size and fluorescence intensity value from an individual particle is normalized by its size or volume and used to differentiate between pollen and allergens from microbes. 
     
     
         10 . The method of  claim 1 , wherein the fluid comprises air. 
     
     
         11 . The method of  claim 1 , wherein the fluid comprises water. 
     
     
         12 . A method for detecting and classifying a particle in a liquid or gas comprising illuminating the particle with a UV light source, and simultaneously measuring a size of the particle and any intrinsic fluorescence from the particle. 
     
     
         13 . The method of  claim 12 , wherein the particle comprises a bioparticle. 
     
     
         14 . The method of  claim 13 , wherein the bioparticle comprises a microbe. 
     
     
         15 . The method of  claim 12 , wherein the bioparticle is selected from the group consisting of a bacterium, a mold, a fungi, and a spore. 
     
     
         16 . The method of  claim 12 , including the step of measuring fluorescence intensity. 
     
     
         17 . The method of  claim 12 , including the step of comparing particle size information and fluorescence intensity to classify the particle as inert or microbial in origin. 
     
     
         18 . The method of  claim 12 , including the step of differentiating the particle as a bacterium, a mold, a fungi or a spore. 
     
     
         19 . The method of  claim 12 , including the step of differentiating the particle as a pollen or an allergen. 
     
     
         20 . The method of  claim 18 , including the step of classifying the particle based on its fluorescence response. 
     
     
         21 . The method of  claim 19 , including the steps of classifying the particle based on its fluorescence response. 
     
     
         22 . The method of  claim 18 , including the steps of classifying the particle based on its diameter or volume. 
     
     
         23 . The method of  claim 18 , including the steps of classifying the particle based on its fluorescence intensity normalized by its diameter or volume. 
     
     
         24 . The method of  claim 19 , including the steps of classifying the particle based on its diameter or volume. 
     
     
         25 . The method of  claim 19 , including the steps of classifying the particle based on its fluorescence intensity normalized by its diameter or volume. 
     
     
         26 . A particle detector system, comprising:
 a sample cell;   a light source on one side of a sample cell for sending a focused beam of light through the sample, whereby portions of the beam of light are scattered at various angles by particles of various sizes present in the sample area, and an unscattered portion of the beam of light remains unscattered;   a beam blocking device on an opposite side of the sample cell for blocking at least the portion of the unscattered portion of the beam of light and for limiting a range of particles measured;   a first detector positioned in the light path after the beam blocking device for detecting a portion of forward scattered light, and producing an output including information on the size of a single particle in the light path within a predetermined size range;   a second detector positioned off axis from the beam of light for detecting intrinsic fluorescence from said same single particle.   
     
     
         27 . The system of  claim 26 , wherein an elliptical mirror is located in a particle sampling region such that an intersection of the incoming particle stream and the light beam are at one foci of the ellipsoid, and the second detector is at the other foci. 
     
     
         28 . The system of  claim 26 , further comprising an alarm unit for providing a warning signal when a particle within a predetermined size range is detected which also fluoresces. 
     
     
         29 . The system of  claim 26 , wherein the light source emits ultraviolet radiation. 
     
     
         30 . The system of  claim 26 , wherein the light source comprises a LED. 
     
     
         31 . The system of  claim 30 , further comprising a collimator lens optically positioned between the light source and the first detector. 
     
     
         32 . The system of  claim 26 , further comprising a processing unit for processing particle size distribution and particle fluorescence at a give time, and displaying a histogram of the particle on an output device. 
     
     
         33 . The system of  claim 26 , wherein the first detector comprise a photodiode. 
     
     
         34 . The system of  claim 26 , wherein the sample cell comprises an air sample cell. 
     
     
         35 . The system of  claim 26 , wherein the sample cell comprises a water sample cell. 
     
     
         36 . The system of  claim 26 , further comprising computer readable program code for integrating detected particle size and detected intrinsic fluorescence.