Pathogen and particle detector system and method

Abstract

A particle detector has a sample area of cross section no in excess of about 2 mm for containing environmental fluid, a light source on one side of the sample area for directing a collimated or nearly collimated beam of light through the sample air or water so that part of the light beam will be scattered by any particles present in the air or water while the remainder remains unscattered, and a beam diverting device on the possible side of the sample area for diverting or blocking at least the unscattered portion of the beam of light and directing at least part of the scattered light onto a detector. The detector produces output pulses in which each pulse has a height proportional to particle size and a pulse height discriminator obtains the size distribution of airborne particles detected in the air or water sample at a given time from the detector output. The detector may also include a device for discriminating between biological agents and inorganic particles.

What is claimed is: 
     
         1 . A flow cell for a particle detection apparatus comprising:
 an inlet in fluid communication with a source of fluid to be measured;   an outlet;   a fluid moving unit in fluid communication with the outlet;   a first channel defined by the flow cell between and in fluid communication with the inlet and the outlet, the channel having a sampling region where particles carried in a fluid from the inlet are measured, and   a second channel defined by the flow cell between and in fluid communication with the inlet and the outlet.   
     
     
         2 . The flow cell of  claim 1 , wherein the second channel is arranged substantially parallel to the first channel. 
     
     
         3 . The flow cell of  claim 1 , wherein the sampling region comprises an optical window enabling optical interrogation of particles in the fluid from the inlet. 
     
     
         4 . The flow cell of  claim 1 , wherein the inlet is conical. 
     
     
         5 . The flow cell of  claim 1 , wherein the outlet is conical. 
     
     
         6 . The flow cell of  claim 1 , wherein the second channel connects the inlet to the outlet. 
     
     
         7 . The flow cell of  claim 6 , wherein the inlet and the outlet are conical, having bases arranged transverse to a flow of fluid to be measured, and define apertures at their apices, wherein the first channel connects to the inlet and the outlet at their respective apices, and the second channel connects to the inlet and the outlet at a point approximately halfway between the apices of the inlet and the outlet and their respective bases. 
     
     
         8 . The flow cell of  claim 1 , further comprising a third channel defined by the flow cell between and in fluid communication with the inlet and the outlet. 
     
     
         9 . The flow cell of  claim 8 , wherein the second and third channels are arranged to either side of the first channel and are parallel to the first channel along some portion of their length. 
     
     
         10 . The flow cell of  claim 1 , wherein the flow cell has an exterior surface that is electrically grounded. 
     
     
         11 . The flow cell of  claim 10 , wherein the flow cell has an exterior surface that is metalized. 
     
     
         12 . The flow cell of  claim 1 , wherein the first channel has a cross-sectional diameter of between about 1.5 mm to 2.0 mm. 
     
     
         13 . A method of sampling particles in a fluid, comprising:
 inducing a flow of fluid containing particles from a source into an inlet;   splitting the flow into a sample flow and at least one bypass flow;   supplying the sample flow to a sample channel   sampling the sample flow to detect information regarding particles in the sample flow, and   rejoining the sample flow and the bypass flow into a rejoined flow after the sample flow has been sampled.   
     
     
         14 . The method of  claim 13 , further comprising accelerating the sample flow prior to sampling. 
     
     
         15 . The method of  claim 13 , wherein inducing a flow of fluid containing particles comprises drawing the flow of fluid from the source and through the inlet. 
     
     
         16 . The method of  claim 13 , further comprising splitting the flow into a second bypass flow, and rejoining the sample flow and the second bypass flow into the rejoined flow after the sample flow has been sampled. 
     
     
         17 . The method of  claim 13 , wherein sampling the sample flow comprises optically interrogating particles in the sample flow. 
     
     
         18 . The method of  claim 13 , further comprising decelerating the sample flow after sampling. 
     
     
         19 . A particle detector, comprising:
 an inlet in fluid communication with a source of fluid to be measured;   a fluid flow apparatus defining a plurality of fluid flow channels in fluid communication with the inlet, wherein at least one of the fluid flow channels defines a sampling region enabling sampling of particles within the sampling region,   wherein at one of the fluid flow channels is a bypass flow channel that enables a portion of a fluid flow entering the inlet to flow around the sampling region.   
     
     
         20 . The particle detector of  claim 19  further comprising an outlet in fluid communication with the plurality of fluid flow channels, wherein the bypass flow channel connects the inlet and the outlet.