Abstract:
An apparatus is provided for detecting an atmospheric component. The apparatus comprises one or more arrays, wherein each array comprises one or more colorimetric reagents. A material encapsulating the colorimetric reagents of each array is capable of being at least partially removed to expose the colorimetric reagents of a selected array to the atmosphere. An imager detects colors of the one or more colorimetric reagents in the selected array. Circuitry then determines changes in colors of the one or more colorimetric reagents within the selected array.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Application No. 60/511,488, filed 14 Oct. 2003. 
     
    
     FIELD OF INVENTION  
       [0002]     The present invention generally relates to a device for determining the presence of an atmospheric component and more particularly relates to a device for alerting the device user and others of the presence of an unwanted environmental agent.  
       BACKGROUND OF THE INVENTION  
       [0003]     First responders, such as fire fighters, police, or HAZMAT personnel, many times arrive at the site of an emergency situation without the ability to detect environmental hazards such as toxic industrial chemicals, chemical warfare agents, or radiation. Such inability may result in physical harm to the first responders and other responders that follow. Large quantities of toxic industrial chemicals may be present ‘normally’ in populated areas: industrial sites, storage depots; transportation and distribution facilities, resulting in the potential for accidents such as the accidental release of methylisocyanate in Bhopal, India in 1984. Other toxic industrial chemicals, for example, include ammonia, chlorine, hydrogen chloride, and sulfuric acid. Chemical warfare agents are usually more lethal than toxic industrial chemicals. Nerve agents are the most common chemical warfare agents, such as the nerve agent Sarin that was used in the 1995 Tokyo subway gas attack. Other chemical warfare agents, for example, include Tabun, sulfur mustard, and hydrogen cyanide.  
         [0004]     Chemical warfare agents typically are medium to high volatility and therefore may be detected in the gas phase. Electronic monitors for chemical warfare agents are based on electronic detection using ion-mobility-spectrometry, photo-ionization, and flame-ionization. These tools offer a broadband response with high levels of sensitivity, but most suffer from interference effects caused by what is often a highly complex chemical background mix at the scene, and most commercial tools exhibit high false-positive responses to contaminants. Furthermore, these devices are not designed to be wearable, and most tools, although handheld, are relatively bulky and fully engage the user detracting from other important duties.  
         [0005]     Known colorimetric methods for detecting such chemical and biological hazards include simple color-change badges generally have a limited life span, e.g., 8 hours, to tubes providing quantitative data with high specificity, but both require the user to assess the color change to determine the hazard level. Furthermore, gas tubes are sensitive to physical abuse and are limited in some cases to only one and in other cases only a few hazards requiring the user to know what type or types of hazards are suspected.  
         [0006]     Radiological threats have become more relevant with the so-called ‘dirty bomb’, which combines explosive blast with surreptitious ‘ingredients’ of radionuclides such as Cs-137, a beta and gamma emitter. Radiological monitors (dosimeters) have been available for many years, mostly for occupational safety monitoring.  
         [0007]     Pager style, wearable units, having audio/visual alerts built-in are available for such monitoring. Also, a variety of miniature radiation detectors exist, such as small Geiger-Muller tubes, selective scintillation layers with photo-sensors, and silicon diodes. Probes can be attached to other types of monitors, covering any of the radiation species, but these monitors are at best hand-held, and must be maintained regularly. Recently, colorimetric badges that detect radiation have been developed; however, these require the user to constantly monitor its status.  
         [0008]     Accordingly, it is desirable to provide a low cost, low power, miniaturized (wearable), reliable (having fewer negatives and false positives) apparatus for detecting the presence of environmental agents and transmitting the results to the user and others without disrupting the user&#39;s duties.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     An apparatus is provided for detecting an atmospheric component. The apparatus comprises one or more arrays, wherein each array comprises one or more colorimetric reagents. A material encapsulating the colorimetric reagents of each array is capable of being at least partially removed to expose the colorimetric reagents of a selected array to the atmosphere. An imager detects colors of the one or more colorimetric reagents in the selected array. Circuitry then determines changes in colors of the one or more colorimetric reagents within the selected array 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and  
         [0011]      FIGS. 1-5  illustrate a cross sectional view of four embodiments of colorimetric reagents;  
         [0012]      FIG. 6  illustrates a top view of colorimetric reagents in an array;  
         [0013]      FIG. 7  illustrates a top view of a group of colorimetric reagent arrays;  
         [0014]      FIG. 8  illustrates a block diagram of a system including the array of colorimetric reagents;  
         [0015]      FIG. 9  illustrates a top view of an array of colorimetric reagents in yet another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0016]     The following detailed description of the invention is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description of the invention.  
         [0017]     Referring to  FIG. 1 , an imager  14  is positioned between a base  12  and colorimetric reagents  16 . The base  12  may comprise packaging, an integrated circuit board, or a semiconductor material and may include interface circuitry, a processor, etc., in a manner known to those skilled in the art. The imager  14  may comprise, for example, charge coupled devices which are basically storage and conversion devices capable of changing incoming photons into a voltage.  
         [0018]     The colorimetric reagents  16  comprise a thin layer of a chemical that maintains a certain color in ambient air, but changes color when subjected to a specific gaseous agent. Examples of chemicals that could be used as colorimetric reagents include the following:  
         [0019]     For the testing for carbon monoxide (CO), the colorimetric reagent  16  comprising K 2  Pd (SO 3 ) 2  would turn from yellow to black in accordance with the equation: 
 
CO+K 2  Pd (SO 3 ) 2  yields K 2  (SO 3 ) 2  Pd CO, where K 2  (SO 3 ) Pd CO yields CO 2 +SO 2 +Pd+K 2 SO 3 . 
 
         [0020]     For the testing for ammonia (NH 3 ), the colorimetric reagent  16  comprising H 3 PO 4  would turn from blue to pink in accordance with the equation: 
 
2NH 3 +H 3 PO 4  yields (NH 4 ) 2  PO 4 . 
 
         [0021]     For the testing for hydrogen sulfide (H 2 S), the colorimetric reagent  16  comprising Ag would turn from white-gray to black in accordance with the equation 
 
H 2 S+Ag yields AgS. 
 
         [0022]     For the testing for organic matter (RCH 2 OH), the colorimetric reagent  16  comprising KMNO 4  would turn from purple to brown in accordance with the equation: 
 
RCH 2 OH+KMNO 4  yields RCOO—K++MNO 2 +KOH. 
 
         [0023]     Another test for organic matter, the colorimetric reagent  16  comprising Cr 2 O 7  would turn from orange-red to green in accordance with the equation: 
 
RCH 2 OH+Cr 2 O 7  yields RCHO+Cr 3 . 
 
         [0024]     For the testing for inorganic matter, such as a Hydrogen Chloride (HCL) mist, the ph indicators Bromophenol blue would change from red to blue, and Mehtylene orange would change from orange to green.  
         [0025]     A light source  18  optionally is provided for directing light  20  onto the colorimetric reagents. The light source provides a known spectrum that results in a more reliable determination of the colors of the colorimetric reagents than is provided by ambient light.  
         [0026]     The colorimetric reagents  16  are encapsulated in a material  26 , e.g., glass, plastic, and low melting-point metals) that may have a portion selectively removed to create an opening  27  by, for example, a heater  28  (see  FIG. 5 ). The heater  28  is coupled electrically to the base  12  by electrical connection  29 . In another embodiment, the material  26  may be mechanically removed by, for example, punctuating or peeling off a protective cover. As an unwanted environmental agent in introduced, it would flow through opening  27  into cavity  32  and onto the colorimetric reagents  16 .  
         [0027]     A heater  30  is positioned so as to prevent the temperature from dropping to an extent that would prevent the chemical reaction in the colorimetric reagents  16  from occurring.  
         [0028]      FIGS. 2-4  illustrate alternative embodiments of the invention. In  FIG. 2 , a transparent layer  22  is positioned between the colorimetric reagents  16  and the imager  14 . In  FIG. 3 , a spacer  24  is positioned between the transparent layer  22  and the imager  14 . The transparent layer  22  would allow for easy removal of the colorimetric reagents  16  permitting reuse of the imager  14  and base  12 .  
         [0029]     In  FIG. 4 , the spacer  24  is positioned between the imager  14  and the colorimetric reagents  16 , with the transparent layer  22  positioned on the opposed side of the colorimetric reagents  16 . In this case, the environmental gas to be detected would flow through the spacer  24  and around the colorimetric reagents between the transparent layer  22  and the imager  14 . Another embodiment might include a lens positioned between the colorimetric reagents  16  and the imager  14  for focusing the light reflecting from the colorimetric reagents  16 .  
         [0030]     Referring to  FIG. 6 , an array  50  comprises a plurality of colorimetric reagents  16 . Although a 4×4 array is shown, any number of the colorimetric reagents  16 , it is understood that the array  50  could comprise one or more of the colorimetric reagents  16  may be utilized. An array  50  with multiple colorimetric reagents  16  of the same type provides redundancy. If the chemical in one colorimetric reagent  16  malfunctions, the other colorimetric reagents  16  would still provide an accurate reading. Furthermore, the colorimetric reagents  16  could be of various types, thus providing the ability to simultaneously test for a number of unwanted environmental agents at the same time.  
         [0031]     Referring to  FIG. 7 , an apparatus  60  includes a number of arrays  50 . Although a 3×3 array is shown, it should be understood that any number of arrays could be included, such as 1×2, 1×3, 3×3, or much larger. The use of multiple arrays  50  allows for the use of one array at a time. The use of a second array could be used to confirm a reading from the first array, or the second array could be used on a second day, the third array on a third day, and so forth.  
         [0032]     Referring to  FIG. 8 , the colorimetric imaging array device  70  includes apparatus  60  coupled to base  12  which includes interface circuitry and processor. The base  12  may be coupled to a display  72  for visually displaying information provided from the processor, an RF interface  74  for transmitting the information to others, and an alarm  76  that would audibly and/or visually alert the user. The processor and RF interface  74  may also include circuitry for providing GPS information.  
         [0033]     One drawback experienced with the use of colorimetric reagents  16  is interference of a second gas in the presence of the unwanted gas that may cause the colorimetric reagents  16  to give a false reading. Referring to  FIG. 9 , a substance  82  is positioned in the flow of the unwanted gases prior to the gases reaching the colorimetric reagents  16 . The substance  82  would absorb the second gas so as to allow the colorimetric reagents  16  to “see” only the unwanted gas. Examples of the substance  82  include activated carbon (C(Ac)) to remove organic species, such as H 2 S, for the detection of inorganic gases, such as CO and HCL; and SiO 2  dessicant to remove H 2 O. The substance  82  could also be used to remove humidity, or other obstacles to the colorimetric reagents  16  giving a proper reading.  
         [0034]     While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.