Abstract:
An indicator that is an adhesive label-like testing indicator that is used to detect the presence of trace chemical residues, e.g., explosive compound residues or other hazardous chemicals. The indicator comprises a substrate, preferably transparent, having an upper surface and a lower surface and a first portion and a second portion joined at a fold line, the first portion being smaller in area than the second portion. A pressure sensitive adhesive coats the upper surface of at least the second portion of the substrate. A first reactant is adhered to the upper surface of the first portion of the substrate. When the upper surface of the second portion, is contacted with a surface containing the trace chemical residues, e.g., the handle of a briefcase, the chemical residue adheres to the adhesive. When the first portion is subsequently folded along the fold line so that the upper surfaces of the substrate contact each other, a portion of the adhesive on the second portion remains exposed. This exposed portion may be used to attach the indicator to an article, e.g., a passport or the article tested. Subsequently, over a period of time, the first reactant and any chemical residue present react with each other to provide a color indicia indicating the presence of the chemical residue.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to a disposable sticker that can be used by security personnel guarding a secure area, e.g., airport, airplane, or other transportation vehicle, for detecting the presence of trace amounts of a predetermined chemical residue, e.g., explosives, explosive ingredient, hazardous chemical, biochemical, narcotic, for example on the surface or handle of a briefcase, piece of luggage, or package, that a person is carrying when they enter the secure area. 
         [0003]    Additionally, this invention relates to a chemical residue indicator that provides a positive, visible indication that the article to which it is affixed has been tested for a predetermined type of chemical residue and clearly indicates the results of such test. 
         [0004]    2. Related Art 
         [0005]    It is a common practice for security personnel to inspect and test packages, purses, etc. for dangerous, illegal or hazardous items prior to persons entering secure areas, e.g., airports, public events, etc. In particular, security personnel often inspect and test containers and vehicles for hazardous materials or devices, particularly explosive devices and chemical residues left by such devices and hazardous materials. 
         [0006]    There are numerous electronic devices which are available to test for such chemicals. Many of these devices perform their designed functions well, however they are generally, large and expensive devices that are impractical to install at the tens of thousands of locations that today&#39;s environment demands. Additionally, very often such inspections need to occur on the street, in a garage, on an airport tarmac, where access to sophisticated testing equipment is limited, impractical or impossible. 
         [0007]    There are also a number of non-electronic, chemical trace explosives and hazardous material testers on the market. In all cases, they have liquids in vials or aerosols which are employed to perform color change reactions that indicate the presence or absence of these hazardous materials. Because the testing process requires the security personnel to handle several items, such as liquids, swabs, paper sampling sheets, the testing process is normally time consuming, complicated, and not easily performed in the field. Such testers require the security person to store and retrieve the various components and to manipulate them in an environment that may not be suitable for such testing. 
         [0008]    Often inspected articles, typically hand-carried articles, do not need to be tagged after inspection because the articles may be entering into a secure location, e.g., a luggage handling area of an airport. However, often an inspection is performed at a location in a non-secure area (airport security screening station) and subsequently the person must show in another area (airplane boarding area) that the article was inspected. This requires that a visible inspection indicia, e.g., sticker, be attached to the inspected article. 
       SUMMARY OF THE INVENTION 
       [0009]    The indicator of this invention is an adhesive label-like testing indicator that is used to detect the presence of trace chemical residues, e.g., explosive compound residues or other hazardous chemicals. The indicator comprises a substrate, preferably transparent, having an upper surface and a lower surface and a first portion and a second portion joined at a fold line, the first portion being smaller in area than the second portion. A pressure sensitive adhesive coats the upper surface of at least the second portion of the substrate. A first reactant is adhered to the upper surface of the first portion of the substrate. When the upper surface of the second portion, is contacted with a surface containing the trace chemical residues, e.g., the handle of a briefcase, the chemical residue adheres to the adhesive. When the first portion is subsequently folded along the fold line so that the upper surfaces of the substrate contact each other, a portion of the adhesive on the second portion remains exposed. This exposed portion may be used to attach the indicator to an article, e.g., a passport or the article tested. Subsequently, over a period of time, the first reactant and any chemical residue present react with each other to provide a color indicia indicating the presence of the chemical residue. 
         [0010]    This invention is a low cost, simple to use, portable, disposable adhesive sticker indicator for trace testing for chemical residues that can be widely distributed to security personnel, such as customs agents, TSA personnel, police officers, fire department personnel, the national guard, for use on the “frontline.” The indicator provides a quick “go/no-go” color change and requires only minimal training to teach someone how to use the detector. 
         [0011]    Because the indicator is simple and convenient to use, it is more apt to be used. Other electronic or liquid chemical trace explosive detection systems are not widely used because of their cost and complexity. 
         [0012]    The test indicator of this invention is always ready for use—no warm up or calibration is required, as do electronic devices. The screening of the article can be performed in place, it does not have to be brought to a central screening point. The indicator can be adhesively attached to the object being tested, so that no writing or documentation is required to link the test results to the article. 
         [0013]    The indicator of this invention permits items to be tested while people are waiting in line, and while waiting, the color develops indicating the test results. 
         [0014]    Additionally, the indicator lays flat so that it can be attached to documents and objects and the test color appears rapidly. 
         [0015]    Additionally, after activation, the indicator cannot be reused. 
         [0016]    Further, because the indicator can be viewed by several security personnel, it is difficult for one or more persons to permit an insecure package from entering a facility. 
         [0017]    Still further, the test can be performed with only one hand, thus permitting the testing personnel the opportunity to hold the article being tested or if necessary, to hold a weapon. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Other important benefits and features of the invention will be apparent from the following Detailed Description of the Invention taken in connection with the accompanying drawings in which: 
           [0019]      FIG. 1  shows a preferred construction and configuration of the indicator  20  of this invention. 
           [0020]      FIG. 2  is a schematic cross-section of the first portion  30  of indicator  20  prior to activation. 
           [0021]      FIG. 3  is a schematic perspective view of the indicator  20  just prior to activation. 
           [0022]      FIG. 4  is a plan view of the indicator  20  just after activation. 
           [0023]      FIG. 5  is a plan view of the indicator  20  a period of time after activation. 
           [0024]      FIG. 6  shows another embodiment of the indicator  61  of this invention. 
           [0025]      FIG. 7  is a schematic perspective view of indicator  61  just prior to activation. 
           [0026]      FIG. 8  is a plan view of the indicator  61  just after activation. 
           [0027]      FIG. 9  is a is a plan view of the indicator  61  a period of time after activation 
           [0028]      FIG. 10  shows another embodiment of the indicator  90  of this invention. 
           [0029]      FIG. 11  is a is a plan view of the indicator  90  a period of time after activation. 
           [0030]      FIG. 12  shows another embodiment of the indicator  90  of this invention. 
           [0031]      FIG. 13  shows another embodiment of the indicator of this invention. 
           [0032]      FIG. 14  shows the embodiment of the indicator of  FIG. 13  after activation. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    The shape and construction of several embodiments of the testing indicator are shown in  FIGS. 1-14 . 
         [0034]      FIG. 1  shows the preferred construction of the indicator  20 . The components of the first portion  30  of indicator  20  are shown in schematic in  FIG. 2 . Referring to  FIGS. 1 and 2 , the preferred indicator  20  comprises a clear substrate  50  which forms the face stock for the web assembly  10 . Substrate  50  may, for example be a polyester film with thickness of 1 to 10 mils. The substrate  50  is clear so that the color change caused by reactant  53  can be viewed. Printing maybe applied to the front of the substrate  50 . Such printing could be instructions, such as fold-over or fold-here. Other print indicia can be provided, for example to indicate the type testing indicator. Additionally or optionally, a security indicia can be provided to prevent counterfeiting or removal from a surface to substitute another sticker in its place. 
         [0035]    Referring to  FIGS. 1 and 3 , web  10  may be die-cut into a plurality of indicators  20 . The indicators could be of any shape that is convenient to the user, e.g., rectangular, round, or the preferred T shape as shown herein. As shown in  FIGS. 2 and 3  The T shape permits the first portion  30  which has the display surface  26  thereon to be easily folded over along the fold line  32  onto the second portion  40  which has the adhesive sampling surface  42  thereon. Such construction permits the display surface  26 ,  30  to stick to the adhesive surface  42  that is on the second portion  40  leaving a portion of the adhesive area  42  surrounding the first portion  30  ( 21  in  FIGS. 4 and 5 ) exposed to permit attachment of the indicator  20  to the article tested or to documents associated with the person carrying the article tested. 
         [0036]    Referring to  FIG. 2 , on the underside of the clear substrate  50  is clear adhesive  51  which may have various organic compositions mixed within the adhesive  51  to form the color forming compositions, e.g., a resin matrix. The adhesive coating  51  covers the entire surface of substrate  50  and is protected from the environment by a release paper  55  that has thereon a silicone coating  54 . Printing, such as instructions, can be applied to the rear surface of the release liner  55 . 
         [0037]    For air sensitive materials as well as materials that lose or gain moisture, the entire indicator can be hermetically sealed. The indicator can be distributed to the user as a single unit, for example as shown in  FIG. 3 , or packaged in sheet form, for example as shown in  FIG. 1  for use in testing numerous packages over a period of time, e.g., a users shift of employment. 
         [0038]    Referring to  FIG. 2 , attached to the adhesive layer  51  and sandwiched between the face stock  50  and the release liner  55  is the display surface  52  having the color-forming reactants on the surface in contact with the silicone liner  54 . The display surface is typically white for bright visibility. The color forming chemicals or reactants can be printed as a uniform coating  53  on the display surface  52  or they can be applied in patterns or bands as shown in subsequent figures. 
         [0039]    Preferably, the display surface  52  is non-porous so as not to absorb or permit any of the organic liquids in the adhesive  51  on the clear substrate  50  to penetrate therethrough. 
         [0040]    Referring to  FIGS. 2 and 3 , in a preferred embodiment, when using the indicator  20  to test for reactants, one lifts the indicator  20  off the release liner  54 ,  55 , and then contacts and presses the adhesive  51  and reactant  53  several times to a surface to be tested, e.g., luggage handle or vehicle door, to extract a sample of any trace residue that is present. 
         [0041]    Referring to  FIG. 3 , the first portion  30  or reactant display surface  26  is then folded onto the opposing adhesive  40  to initiate the reaction and color change process. (See  FIGS. 4 and 5 ). The indicator  20 , as shown in its activated (reacting) form in  FIG. 4 , is attached to the tested article or related documents by adhering the adhesive area  21  not covered by portion  30 , to the article. One can then see the reactant display surface  26  through the clear transparent portion  30  change in color from, for example, indicia  28  in  FIG. 4  to indicia  22  in  FIG. 5 , as the individual color reactants for specific types of chemical residue, e.g., explosives, cause the color change. 
         [0042]    Referring to  FIGS. 2 and 3 , the clear substrate  50  of the web becomes the viewing window  26  on the testing sticker  20 , carries a sample of the chemical residue that was collected from the tested article, and also carries the organic compounds and constituents for facilitating the reagent reactions on the display face  53  and provides adhesive  51  for the attachment of areas  21  to the article or accompanying documents. 
         [0043]      FIG. 5 , which shows the indicator  20  a period of time after activation, indicates that several of the color reacting areas  22  have turned dark and changed color, thus indicating to the tester that some explosives or other target chemicals have been detected. For security screening purposes, it may not be important for the tester to know the chemical that was detected, only that a positive response has occurred and that a more detailed scrutiny of the package and accompanying individual is required. Likewise, if the indicator does not change color, e.g., remains white, the package and associated individual can be cleared. 
         [0044]      FIG. 6 , depicts another embodiment the indicator  61  of this invention die-cut to a different shape, i.e., a rectangle. In this case, the web  60  is constructed exactly as shown in  FIG. 2  with the display material  52  sandwiched between the adhesive face stock  51  and the silicone liner  54 . The first portion  63  runs along one edge of the rectangular web  60  and leaves a second portion of the clear adhesive face stock  62  exposed. 
         [0045]    As shown in  FIG. 7 , the sampling for substances on articles is performed by touching the adhesive  65  to the surface of the article. The display area  64  is then folded over to initiate the color reaction sequence for testing which is viewed through window  66  in portion  62  of the test indicator  61 . 
         [0046]      FIG. 8 , shows the color changing area  67  just after activation, i.e., folding. After a period of time, as shown in  FIG. 9 , some or the reactive area has changed color as indicia  69  appear indicating a positive test for the target chemical residue. 
         [0047]    The test indicators can be printed (coated) in any pattern. As shown in  FIG. 10 , color forming reactants can be applied as discrete areas so that each area of reactant determines a specific substance or explosive. Optionally, the color forming reactants can be coated as a uniform mixture so that the entire surface  92  becomes the color changing area. For example, the areas  93  on flap portion  92  could each contain reactants for different explosives. In this construction, the testing indicator would sample for 9 different explosives and show which type of explosive is detected. When the test indicator is folded over, as shown in  FIG. 11 , the viewer looks at the array of indicia  94  and from the color change on a specific indicia  94  a determination as to the type chemical residue, e.g., explosive, could be determined. 
         [0048]    Likewise referring to  FIG. 12 , the color reactants have been applied as continuous bands along the display area  98 . The relative position of the bands that change color would indicate the specific substance detected. 
         [0049]    Whereas the foregoing embodiments show indicators which are a constructed of a flat substrate that can be folded over for activation, it is possible to construct the indicators having a plurality of elements which perform the same function. 
         [0050]    Referring to  FIGS. 13 and 14 , a cross-sectional view of another embodiment of the indicator  100  of the type wherein two materials  102  and  104  are attached together and the structure is activated in a similar manner of folding over a portion  106  of the structure  104  to bring the adhesive sampling area  108  into contact with the color forming reactant display area  106 . More specifically, and as shown in  FIGS. 13 ,  14 , the separator  110  between the adhesive sampling surface  108  and the color forming reactants  106  is in the form of a pull tab separator  110 . The tester exposes the adhesive surface  108  by removing the separator  110 , contacts the adhesive with the article to sample the surface to test for the chemical residue and then folds the adhesive back  106  onto the color forming reactant display area  108 . 
         [0051]    Generally, however, it is preferred that these indicators be constructed of one-piece. A one-piece sticker can be used with one hand and the tester does not have to manipulate different pieces of paper or plastic. 
         [0052]    These indicators or test stickers do not require any auxiliary hardware, power source, or batteries. A security person cannot be expected to assemble two or more components properly while standing in a field or on a roadway, possibly while holding a weapon. The testing person may not have a table or work surface for such assembly. It is the one-piece, self-alignment, and go/no-go color-changing construction of these testing stickers that make the invention highly beneficial. 
         [0053]    In the preferred embodiment, the indicator of this invention has the following unique properties and benefits: 
         [0054]    A one-piece pressure sensitive adhesive sticker that contains two chemically-independent reactive surfaces. 
         [0055]    A pressure sensitive adhesive sticker where the two chemically-independent reactive surfaces are covered and protected from exposure to the environment and foreign matter before use. 
         [0056]    A pressure sensitive adhesive sticker with a clear viewing window to observe any color change on either of the two reactive surfaces. 
         [0057]    A pressure sensitive adhesive sticker where the two reactive surfaces can be brought into accurate alignment and contact with each other with the person employing only one hand. 
         [0058]    Stickers constructed such that once the activation for testing has been initiated, the sticker can be affixed to an the article or person being tested. 
         [0059]    These stickers or indicators are intended for use without other equipment or hardware. They are intended to be used by people in field operations(typically standing at remote locations) as well as at desk and inside facilities like airport concourses. What is more important, they are intended to be used by people who do not always have both hands available because of other tasks that they are performing. In an extreme case such as a military situation, this may be while solders are holding their weapon with one hand. 
         [0060]    The testing stickers are intended to be used to sample the article for traces of specific substances such as explosives, narcotics, etc. Upon activating the sticker, a color change will occur if traces of the substance are detected. The chemical technologies employed in these color-changing time-stickers and the color-changing testing stickers are well known to EOD and law enforcement personnel. 
         [0061]    Some of the elements of this invention are known, see, for example, U.S. Pat. Nos.: 5,364,132; 5,446,705; 5,602,804; 5,715,215; 5,873,606;5,719,828; 5,785,354; 5,822,280; 5,930,206; and 5,957,458. The entire disclosures of these patents are incorporated herein by reference. 
         [0062]    An example of a detection system that could be used in this invention is described in U.S. Pat. No. 5,296,380 to Margalit, the entire disclosure of which is incorporated herein by reference. Thus, for example, to detect nitroaromatic explosives, the first reagent band could be an alkaline resin containing an diazotizable amino aromatic azo-dye precursor; for detecting organic nitrates and nitramines, the second reagent could be an acidic resin containing nitrate to nitrite ion reducing agent and a diazo-coupler; for detecting inorganic nitrates, the third resin could be a resin containing zinc powder; for detecting chlorates and bromates, the fourth reagent could be an acidic resin with inorganic nitrates and an aniline salt. Margalit states that these four color detection reagents provide an excellent system for detecting explosives. 
         [0063]    Another example of a detection system that could be used in this invention is described in U.S. Pat. No. 4,788,039 to Glattstein, the entire disclosure of which is incorporated herein by reference. Thus, for example, the adhesive sampling layer can include a solvent such as dimethylsulfoxideand a coating of tetra-alkyl ammonium or phosphonium hydroxide on the reactant surface. Glattstein states that this change accelerates the elimination reaction of nitrate esters, producing the preferred nitrate ions which can be readily detected by a second reagent that produces the well-known Griess reaction to produce a colored azo dye. This dye color change can be viewed on the reaction surface through the clear support film which acts as the viewing window. Glattstein also states that nitroamines undergo alkaline cleavage to form nitrite ions, which produce the same colored azo compound by the Griess reaction. Likewise, polynigroaromatics form lightlycolored (violet-dark) compounds upon reaction with this reaction. Thus, this provides a multi-reagent test kit for the presumptive identification of traces of explosives. The indicator of this invention may be made “secure.” By “secure” it is meant that it cannot be removed from an article and reapplied to another article. Additionally, the indicator cannot be left on an article and used at another time. Additionally, the indicator may be made so that it is tamper indicting, i.e., an attempt to remove the indicator is obvious to one observing the indicator after it has been tampered with. Surfaces covered with pressure sensitive adhesives can be made tamper indicating and resistant to removal by a variety of conventional means. 
         [0064]    The indicator of this invention is used for the detection of a contaminant substance, for example, explosives, drugs, poisons, etc. The inspector removes the sticker from its protective liner (e.g., silicone coated paper) and samples the suspect article by touching the adhesive portion to the surface of the article. This can be done repeatedly and the inspectors fingers can be used to press from the rear the adhesive surface of the sticker onto the sampling surface. These stickers are typically about 2″ or 3″ long in order to have enough surface area for the fingers to apply pressure. In trace explosives detection, some of the surface absorption and top surface contamination will remain attached to the adhesive of the sticker. The adhesive of these stickers will typically have organics captured in the adhesive itself, so this will assist with the transfer of the substances to the adhesive surface. 
         [0065]    With the substrate of the sticker being a clear plastic material like 0.001″ or 0.002″ polyester, one can view the indicating surface through the exposed clear adhesive side of the sticker. The chemical reaction and color change may occur in a matter of seconds or minutes, so the tester can determine very quickly if the article has been exposed to explosive materials or other chemicals. With the remaining exposed adhesive surfaces, the sticker can be attached to the article that was just tested, or it could be attached to some document of the owner of the article such as their airline or rail ticket. 
         [0066]    Whereas the configuration of the testing sticker can be a variety of forms such as those shown in the Figures, a rectangular configuration, and others, each configuration possesses the four specific functional components required in the testing function: 1) the adhesive sampling surface, 2) the color-forming reactant surface, 3) the fold-over activation (and alignment) property, and 4) the clear viewing window property. 
         [0067]    Depending on whichever configuration is used, the sticker can provide the very important (additional) property of attaching the testing sticker to the article or to documents associated with the article tested. Since the testing sticker will provide verification results of the security or analytical test, it is important to be able to associate the specific testing sticker with a particular article. 
         [0068]    The chemical reactants can be applied as discrete circles or squares on the testing sticker reactant surface or as discrete bands along the testing sticker reactant surface. Bands of reactant are preferred along the testing surface because bands of chemicals can be applied continuously from solution during the production process. From the functional point of view, bands will provide a larger area for detecting explosives on the adhesive samples surface. 
         [0069]    A trace sample of explosive that does not cover the entire sampling surface could very well miss a small circle of reactant when the adhesive sampling surface if folded over on the reactant surface. 
         [0070]    The indicator of this invention provides an operational process that permits screeners to perform their screening task when ever and where ever they need to. If the operation process performed by the security screener is too complicated or too clumsy, the screening test will fail to be performed properly or will not be performed at all. 
         [0071]    Some of the other benefits of this detector (sticker) are: 
         [0072]    Carrying the Detection Stickers: The indicators are provided on flat sheets that are unbreakable and hundreds of them can fit into a small envelope, and have an excellent “shelf life.” 
         [0073]    Picking up the Stickers with fingers: Each sticker has a dry tab for lifting off the release liner. This can be done with only one hand which is a benefit in the field where a screener may be carrying a weapon or be holding onto to something. Also, because of the tactile feel, retrieving stickers may even be performed under windy, dusty, dark, and rainy circumstances. This provides a substantial operational benefit outdoors over a multiple part kit that requires a work surface. 
         [0074]    Sampling an article or vehicle: Because of the T shape construction of the sticker, the screener will hold the adhesive sampler with its extending tab. This provides a convenient arrangement for the fingers to press onto the sampling area to retrieve the trace specimen. 
         [0075]    Performing the test: The screener performs the test by simply folding over the adhesive sample area onto the testing area. This brings the reactants for the color test into contact with the sampling surface which is viewed through the clear face of the Sticker. This activation can be performed with one hand by tactile feel alone. The sticker may also provide testing for more than one explosive by coating bands of reactants on the test area. 
         [0076]    Filing and saving the sticker: Once the trace detection test has been performed, the sticker can be saved (filed/stored) by attaching it to a paper document or to the article itself by the remaining exposed adhesive at each side of the sticker body. This permits fast and positive linkage of the actual test with the article being tested. 
         [0077]    While various changes may be made in the detailed construction and processes of this invention, it will be understood that such changes will be within the spirit and scope of the present invention. Having thus described the invention in detail, it is to be understood that the foregoing description is not intended to limit the spirit and scope thereof. What is desired to be protected by Letters Patent is set forth in the appended claims.