Abstract:
A contaminant detection apparatus comprising a powered portable detection device for detecting the presence of at least one pathogen in a sample; a test applicator kit comprising a sample applicator and a cartridge configured to receive and retain the sample applicator; the sample applicator including a swab having a first and second swab heads for swabbing a surface to obtain a sample, the cartridge and sample applicator being configured such that when the sample applicator is retained in the cartridge, the first swab head is retained in said preserving chamber to preserve a confirmatory version of said sample, and the second swab head is positioned in the solvent chamber to dissolve the second swab head to a substantially liquid mixture including said sample, and permit the mixture to flow via flow paths to the wells.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to the field of pathogen/contaminant detection, and more particularly, to the field of devices for pathogen detection. 
       BACKGROUND OF THE INVENTION 
       [0002]    Pathogens, such as viruses, bacteria, toxins and other contaminants, are omnipresent. Under particular circumstances, such pathogens can become dangerous to human health. For example, the presence of  salmonella  or  E coli  in food can be injurious or fatal to those consuming the food. Anthrax spores can be injurious or fatal to a person who touches or inhales them. There are many examples of circumstances in which particular pathogens can be dangerous to people. 
         [0003]    Apart from the direct danger to humans, there is a serious and detrimental impact associated with indeterminate or tentative discoveries of pathogens. For example, if a suspicion arises that certain food is carrying a pathogen, then, typically, samples would be taken and transported to a lab, where tests would be conducted on the samples under carefully controlled environmental conditions. Until the test results are finally determined, the food (or other environment where the pathogen is suspected) is held in limbo. This delay can be very costly. 
         [0004]    In addition to the cost of delay, there are serious costs associated with incorrect test results. If a test incorrectly returns a negative result, injury or death to humans may result. If a test incorrectly returns a positive result, then food may be destroyed, premises closed, equipment discarded, or disinfection procedures initiated all because of an incorrect test result. 
         [0005]    Tests for pathogens are typically conducted by mixing the sample with a mix of pathogen-specific extraction chemicals, so that if the pathogen is present, light is emitted. This light emission is typically of low intensity, and a Photo Multiplier Tube (PMT) is typically used to sense the emission. A typical PMT consists of seven photosensitive plates arranged in series, with each plate having a successively higher potential applied thereto. The potential difference between each successive plate is typically 100 volts. The first plate releases electrons in response to light, and these electrons are drawn to the next plate because of its higher potential. The third plate draws still more electrons from the second plate because of its still higher potential, and so on. In typical PMTs, the total gain can be adjusted by adjusting the voltage applied to the PMT. For example, a typical PMT may be adjusted so that the potential difference between successive plates is 110 volts instead of 100 volts. The PMT emits an amplified signal which indicates whether light was emitted by the sample. However, PMTs are sometimes imprecise and unreliable. 
       SUMMARY OF THE INVENTION 
       [0006]    Therefore, what is preferred in one aspect is a contaminant detection apparatus effective and convenient for use in the field. What is desired in another aspect is an optical sensor module that improves precision and reliability. 
         [0007]    Therefore, in one aspect, there is provided a contaminant detection apparatus comprising: 
         [0008]    a powered portable detection device for detecting the presence of at least one pathogen in a sample; 
         [0009]    a test applicator kit comprising a sample applicator and a cartridge configured to receive and retain the sample applicator. The cartridge preferably includes a solvent chamber for holding a solvent, preferably includes a preserving chamber for holding a preserver, and preferably includes at least one well for holding at least one pathogen-specific set of extraction chemicals. Preferably, the cartridge further includes a flow path from the solvent chamber to each of the wells. 
         [0010]    Preferably, the sample applicator includes a swab having a first and second swab heads for swabbing a surface to obtain a sample, the cartridge and sample applicator preferably being configured such that when the sample applicator is retained in the cartridge, the first swab head is retained in said preserving chamber to preserve a confirmatory version of said sample, and the second swab head is positioned in the solvent chamber to dissolve the second swab head to a substantially liquid mixture including said sample, and to permit the mixture to flow via the flow paths to the wells. 
         [0011]    Preferably, the cartridge is positionable relative to the portable detection device to permit the portable detection device to detect the presence of at least one pathogen by sensing, and indicating the existence of, luminescence in one or more of said wells. 
         [0012]    Preferably, the cartridge has a code element associated therewith, the code element including an indication of which pathogens are being tested for in each well. Preferably, the code element is a bar code. 
         [0013]    Preferably, the detection device includes a code element reader for reading the code element. Preferably, the detection device includes a microprocessor for controlling functions of said detection device. Preferably, the detection device includes a display, operatively connected to the microprocessor, for displaying information regarding whether one or more pathogens have been detected. Preferably, the detection device is powered by a 9-volt battery. Preferably, the detection device includes an input device, operatively connected to the microprocessor, for programming the detection device. Preferably, the detection device includes a memory operatively connected to said microprocessor and said input device, said input device being configured to permit entry of test-related information for storage in the memory. Preferably, the detection device includes at least one software-programmable button operatively connected to the microprocessor, wherein the functions of said buttons can be programmed in said microprocessor. Preferably, the detection device includes a data transmission connection, operatively connected to the microprocessor, for transmitting data relating to pathogen detection from said detection device. Preferably, the detection device includes a code element reader positionable for reading the code element. Preferably, the detection device further includes an optical sensor module for detecting luminescence in said cartridge, the optical sensor module including a controller operatively connected to the microprocessor. 
         [0014]    In another aspect, there is provided an optical sensor module for sensing luminescence resulting from the presence of a pathogen in one or more extraction chemicals, the module comprising a light sensor configured to emit a signal in response to incident light, and at least one amplification stage, operatively connected to the light sensor, for amplifying the signal to indicate a test result, the module including at least one noise filter for filtering noise from said signal. Preferably, the amplification stages are non-photosensitive. Preferably, the amplification stages comprise operational amplifiers. Preferably, each stage is operatively connected to a gain controller configured to independently control the gain of each stage. Preferably, the gain controller comprises a microcontroller programmed independently control the gain of each stage. Preferably, the module further includes dark current detector, the dark current detector being configured to determine that the test result is negative when only a background dark current signal is detected. Preferably, the dark current detector is a microcontroller. Preferably, the module includes a light maximizer (most preferably in the form of a lens) configured and positioned to maximize the effect of light from a well on said light sensor. Preferably, the module further includes a selector to select, one at a time, individual sets of extraction chemicals whose luminescence is to be sensed by said light sensor in testing for pathogens. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Reference will now be made, by way of example only, to drawings of the invention, which illustrate the preferred embodiment of the invention, and in which: 
           [0016]      FIG. 1  is a plan view of a portion of the preferred detection device according to the present invention; 
           [0017]      FIG. 2A-2C  show side and plan views of the preferred test applicator kit according to the present invention; 
           [0018]      FIG. 3  is a schematic diagram of the preferred wells and flow paths according to the present invention; 
           [0019]      FIG. 4  is a schematic diagram of the preferred detection device according to the present invention; and 
           [0020]      FIG. 5  is a schematic diagram of the preferred optical sensor module according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Referring now to  FIGS. 1-4 , the preferred contaminant detection apparatus  8  includes a test applicator kit (TAK)  10  and a detection device  12 , with the detection device  12  including an optical sensor module (OSM)  14 . 
         [0022]    The preferred TAK  10  includes a dual-headed swab  18  (having heads  20  and  22 ) carried at the end of a sample applicator  16 , the sample applicator  16  functioning as a sample collector. The swab  18  is used to swab surfaces or other areas from which a sample is desired. The sample applicator  16  further includes a handle  24  at one end of a body  26 , with the dual-headed swab  18  being carried at an opposite end of the body  26 . 
         [0023]    The swab  18  is used to gather a sample for testing. Both heads  20  and  22  are brought into contact with the sample area. One of the heads  20  or  22  will, as will be described below, be inserted into a suspension fluid which preserves the sample. This preserved sample will act as a confirmatory sample, if it is desired to retest the sample at a later time. 
         [0024]    The TAK  10  also includes a cartridge  28 , configured to accept the sample applicator  16 . Preferably, the cartridge  28  and sample applicator  16  are configured such that the sample applicator  16  can be inserted into the cartridge  28  with a snap fit, so that the sample applicator  16  is held in the cartridge  28  after the snap fit is engaged. 
         [0025]    The cartridge  28  and applicator  16  are both sized, shaped and positioned so that when the snap fit is engaged, one of the heads (number  20 ) is preserved in a preserver, preferably in the form of a suspension fluid as mentioned above. The preserver is located in a preserving chamber  29 . The other head (number  22 ) is at the same time positioned in a separate chamber  30  within the cartridge  28  containing a solvent. The solvent is selected to dissolve the head  22 , so that the head  22 , together with the sample on the head  22 , dissolve into substantially liquid form. 
         [0026]    The cartridge  28  preferably includes at least one well  32 . More preferably, the cartridge  28  includes a plurality of wells  32 , and most preferably, the cartridge  28  includes at least five wells  32 . It will be appreciated by those skilled in the art that detection tests for pathogens are typically performed using extraction chemicals. These chemicals typically include, for example, alkaline phosphate and/or horseradish peroxide, a pathogen-specific antibody, and a pathogen-specific reactant chemical that causes light emission when the pathogen comes in contact with the extraction chemicals. The test is considered to have a positive result when light is emitted. 
         [0027]    Thus, preferably, each well  32  contains, when the detection device  12  is in use, a pathogen-specific set of extraction chemicals. Most preferably, each well contains the chemicals necessary to test for a different pathogen. In this, way, multiple pathogens (most preferably, at least five) can be tested for using a single sample applicator  16  and cartridge  28 . 
         [0028]    In one possible form of the cartridge  28 , each well  32  comprises a single container for containing a pathogen-specific set of extraction chemicals. However, in another possible embodiment of the cartridge  28 , each well  32  comprises a plurality of containers, with the plurality of containers preferably positioned one above the other. In this other possible embodiment, each extraction chemical from each pathogen-specific set of extraction chemicals is contained in a separate container. By contrast, in the single container embodiment, each set of pathogen-specific extraction chemicals is pre-mixed within the single container of which the well  32  is comprised. It will be appreciated that the multiple-container embodiment will preferably be used in situations where it is disadvantageous to mix the extraction chemicals from each set together before the test is performed. 
         [0029]    In the multiple container embodiment, the cartridge  28  is most preferably configured so that, when the sample applicator  16  is snapped into the cartridge  28 , the plurality of containers of which each well  32  is comprised are opened to one another. The result is that each extraction chemical is mixed together in each well  32  to form the corresponding pathogen-specific set of extraction chemicals. 
         [0030]    Preferably, the cartridge  28  includes a plurality of flow paths  34  which place the chamber  30  in fluid communication with every well  32  in the cartridge  28 . Most preferably, the flow paths  34  take the form of microchannels from the chamber  30  to each well  32 . When the head  22  dissolves into liquid form, the dissolved liquid then travels to each well via the flow paths  34 . The dissolved liquid contains the sample from the head  22 . Therefore, the sample is carried via the flow paths  34  to each well  32 , where the sample is introduced to each pathogen-specific set of extraction chemicals. 
         [0031]    Preferably, the cartridge carries a code element in the form of one or more bar codes  36 . The bar codes  36  contain within them information regarding the test including, preferably, the pathogens being tested for at each well  32 , the date on which the TAK was manufactured, the expiry date of the TAK, and other relevant information. 
         [0032]    As explained above, a positive test is preferably indicated by light being emitted from one or more of the wells  32  containing a pathogen-specific set of extraction chemicals. As will be more particularly described below, the detection device  12 , and in particular the OSM  14 , detects and indicates the presence of such light emissions in order to identify a positive test. 
         [0033]    Preferably, the detection device  12  is battery-powered, most preferably by a 9-volt battery  35 . The detection device  12  may also be powered by a rechargeable battery, AC power, or another power source. However, the use of a battery is preferred because this allows the apparatus  8  to be used more effectively in the field. 
         [0034]    The device  12  preferably also includes a housing  33  for housing the components of the device  12 , providing a support structure for them, and protecting same from the elements. 
         [0035]    Preferably, the device  12  includes a microprocessor  37  for controlling the functions of the device  12  through software Thus, the processor  37  is operatively connected to, inter alia, the display  38 , connections  39  and  41 , memory  43 , buttons  40 , reader  44 , microcontroller  46  and adjuster  41 , which are described below. 
         [0036]    Preferably, the device  12  also includes a display  38  for displaying information. Most preferably, the display  38  is a colour LCD display that is backlit. It will be appreciated by those skilled in the art that providing a colour display with backlighting facilitates the use of the device  12  in the field, including under darker field conditions where a different display would be more difficult to see. It is also preferred that this display comprise a touchscreen, so that information and programming can be inputted to the apparatus  8 . It will be appreciated however, that other input devices besides a touchscreen are possible. What is desired is that the apparatus  8  include an input device to permit the apparatus  8  to be programmed. 
         [0037]    Preferably, the device  12  includes a cellular phone connection  39  and/or a satellite telephone connection  41  to permit wireless communication from almost any location. It will be appreciated by those skilled in the art that, when testing for pathogens, the testing may be done in remote areas. Furthermore, it is often urgent that the test results be communicated as quickly as possible to the relevant authorities or other entities. For this reason, a connection of the sort just described is most preferred, as a data link is possible over such a connection. It will be appreciated that any communication connection over which data transmission is possible will serve this preferred function. 
         [0038]    Preferably, the device  12  includes memory  43 . The microprocessor preferably runs software that permits the user to enter all of the relevant information about the test being conducted (e.g. types of pathogens being tested for, date, location, client ID etc.). Preferably, the software that permits entry of relevant test information will also permit the downloading of said information to an external device, such as a PC. Preferably, the software will also permit this information, as well as information relating to the test results actually obtained, to be transmitted over the communication connection described above. 
         [0039]    Preferably, the device  12  includes a control panel with software configurable buttons  40 . The buttons  40  can serve a variety of functions depending on the preferences of the user. These include initiation of the test, control of the OSM  14  (as will be more particularly described below), the transmission and/or downloading of data, etc. 
         [0040]    Preferably, the device  12  includes a built-in code element reader  44  in the form of a barcode scanner. The bar code scanner is configured to read the bar codes associated with the TAK  10  (and particularly the cartridge), which bar codes indicate what pathogens are being tested for. In addition, the OSM  14  of the device  12  will be programmable, so that the OSM  14  will automatically adjust to perform the test for the pathogen of interest. This adjustment may occur automatically using a preprogrammed microcontroller  46  associated with the OSM  14  in response to the reading of the code element. Alternatively, using the control panel, the microcontroller  46  can be programmed at the time of the test. 
         [0041]    Preferably, the device  12  further includes a temperature adjuster  42  configured to adjust the temperature of the device  12 . The most preferred form of adjuster is a thermoelectric heater/cooler operatively connected to the battery to draw power therefrom. It will be appreciated that proper testing for particular pathogens may require that the sample be held at a particular temperature. The preferred temperature adjuster is configured to adjust the temperature of the sample according to the requirements of the particular test. 
         [0042]    It will be appreciated that the preferred TAK  10  and device  10  are configured so that, to perform the test, the user need only swab the surface, insert the applicator  16  into the cartridge  28 , and insert the cartridge  28  into the OSM  14 . This facilitates the use of the apparatus  8  in the field, because the addition of chemicals by robot, injector, or a technician is not required at test time. 
         [0043]    The preferred OSM  14  will now be described. Preferably, the OSM  14  comprises a plurality of stages. The first stage preferably comprises a light sensor  50 , most preferably in the form of a photo sensitive plate. It will be appreciated that the first stage may comprise any light sensor which emits a signal in response to incident light from a well  32 . 
         [0044]    The OSM  14  preferably includes a plurality of subsequent amplification stages  52 . Most preferably, there are six stages  52 . However, it will be appreciated that another number of stages  52  is possible. What is important is that the OSM  14  (preferably via the stages  50 ,  52 ) emits a signal in response to light emission from a well  32 , the signal being sufficiently strong to permit a positive test to be accurately recognized. 
         [0045]    Preferably, each stage  52  comprises an operational amplifier. Preferably, each operational amplifier is operatively connected to the microcontroller  46 . The microcontroller  46  is programmed to control the gain of each operational amplifier with precision. 
         [0046]    Thus, preferably, each stage  52  has a corresponding gain which is independently adjustable i.e. adjustable independent from the gain at any other stage  52 . This independent adjustability is advantageous, because it permits the microcontroller to exert tight control over the gain at each stage  52 , as well as the overall gain of the OSM  14 . This tight control in turn leads to more accurate test results. The reason for this is that this tight control prevents the gains of the op amps from floating independently away from their nominal values. Such floating could have the effect of skewing the test results. If the gain of one or more stages  52  were permitted to float (as sometimes undesirably happens with traditional photo multiplier tubes), an output signal that would, with the gains at their nominal values, have been above the threshold for a positive test result, might actually show up as being below the threshold for a positive test result, or vice versa. However, because the microcontroller  46  controls the gain of each stage  52  independently and precisely, the test results are more likely to be accurate, because the gains of each stage  52  are more likely to be at or close to their desired nominal values. 
         [0047]    It will also be appreciated that the use of operational amplifiers as the stages  52  allows the stages  52  to be substantially more space sufficient than traditional photo multiplier tubes. Photo multiplier tubes typically use a photo sensitive plate for each amplification stage. These plates make the photo multiplier tube bulky, and inappropriate for use in the field. By contrast, the apparatus  8 , which is preferably the size of a typical cellular phone, can be carried and used for effectively in the field. This is because the operational amplifiers are smaller than photosensitive plates and can also be implemented in the OSM  14  as surface mounted circuitry. Thus, the use of operational amplifiers as the stages  52  makes it possible for the apparatus  8  to be smaller, easier to carry, and easier to use in the field. 
         [0048]    Preferably, each stage  52  will have associated therewith a noise filter  54  associated with the input to the stage  52 , and a second noise filter  54  associated with the output from the stage. Preferably, the noise filter comprises circuitry designed to filter electromagnetic noise from the signal. It will be appreciated that the noise filters  54 , being associated with both the input and output of each stage  52 , can determine what portion of a received signal constitutes noise, because, given the tightly controlled gain of each stage  52 , after the initial photo sensitive stage, the magnitude of the signal at each stage is predictable by the micro-controller  46  and noise filters  54 . 
         [0049]    Though it is preferred to have a noise filter associated with both the input and output of each stage  52 , this degree of noise filtration is not required by the invention. The invention, for example, also comprehends a single noise filter  54  associated with each stage  52 , or, alternatively, a one or more noise filters  54  which single handedly or collectively filter noise at all of the stages  52 . The invention further comprehends one or more noise filters  54  that filter noise at one or more of the stages  52 , but not necessarily all of the stages  52 . 
         [0050]    It will be appreciated that the use of one or more noise filters in association with the stages  52  increases the accuracy of the test result produced by the apparatus  8 . For example, noise can lead to a false positive result if noise enters the signal and gets amplified. Alternatively, noise may swamp the signal produced by the light sensor  50 , thus hiding a positive test result and falsely indicating a negative result. 
         [0051]    At each stage  50 ,  52 , a certain small amount of current, typically referred to as “background dark current” flows even when no light is being emitted and sent by the light sensor  50 . This background dark current is the result of the voltages at the stages  50 ,  52 . As a result, the OSM  14  would tend to produce a non-zero signal because of the background dark current even when no light is being emitted Therefore, preferably, the micro-controller  46  is programmed to measure the signal associated with the background dark current, and to interpret that background dark current signal as a zero signal. It will be appreciated that the micro-controller  46  thus improves the accuracy of the test results produced by the apparatus  8 . Since the background dark current signal is present when there is a zero light emission, the test is most accurate when the micro-controller  46  subtracts the background current signal from the actual signal outputted from the stages  52  to determine the actual signal produced by the light sensor  50  and stages  52 . 
         [0052]    Preferably, the micro-controller is programmed/configured to compensate for changes in the temperature of the OSM  14 . As will be appreciated by those skilled in the art, when temperatures are higher, more current flows. Thus, the signal produced by the OSM  14  in response to a light emission in the well  32  depends on the temperature of the OSM  14  and the circuitry contained therein. Thus, the micro-controller is preferably configured adjust the gains of the stages  52  according to the temperature of the OSM  14  and apparatus  8 . The preferred result is that, if the same test on the same sample is performed under different temperature conditions, the results will be consistent because of the temperature compensation. 
         [0053]    It will be appreciated that the micro-controller  46 , acting as a temperature compensator, provides significant advantages for the apparatus  8 . Specifically, the apparatus  8  can be more effectively used in the field, where temperatures can vary widely. By contrast in a laboratory, the temperature is more carefully controlled. 
         [0054]    Preferably, the OSM  14  includes an automatic gain adjustor in the form of the micro-controller  46 . Specifically, the micro-controller  46  is preferably configured to adjust the gains of the stages  52  automatically, up to predetermined maximums, when a negative test result is initially indicated. Thus, if a negative test result is initially detected, the micro-controller  46  will preferably increase the gain of the stages  52  incrementally and again check the test result to see if it is negative. The micro-controller  46  will continue to raise the gain of the stages  52  up to the predetermined maximums, or until a positive test result is obtained, whichever comes first. 
         [0055]    It will be appreciated, therefore, that the micro-controller  46  acts as a test sensitivity adjustor, acting automatically to increase the sensitivity of the test up to a predetermined maximum. This allows the OSM  14  to adapt to different test conditions, and to determine test results with greater certainty. 
         [0056]    Preferably, the OSM  14  is a self-contained unit which includes a serial communications port  53 , or other communications port for communicating with the micro-processor. It will be appreciated that, in this way, the data from the OSM  14  can be communicated quickly and easily to the micro-processor, which in turn can process the data, display related information to the user, and transmit related information to other locations through the communication connections described above. 
         [0057]    It will be appreciated that, though the OSM  14  forms part of the apparatus  8 , it can also be used in association with separate devices not comprehended by the apparatus  8  and the device  12 . Specifically, the micro-controller  46  and communications port  53  permit the OSM to be used in association with other devices or machines which can receive and process the data outputted by the OSM  14 . Thus, the OSM  14  can be installed as a separate component in other machines or devices, and sold separately for use in association with such other machines and devices. 
         [0058]    Preferably, the OSM  14  further includes a lens  56 . Preferably, the device  12  and OSM  14  are configured so that the lens  56  is positioned so as to focus light emitted from the wells  32  onto the light sensor  50 . It will be appreciated, therefore, that the lens  56  functions as light maximizer. By focusing the light emitted from the wells  32  on to the light sensor  50 , the lens  56  maximizes the effect of the light by focusing the light energy directly onto the light sensor  50 . 
         [0059]    The OSM  14  preferably further includes a selector, preferably in a form of a shutter array  58 . Preferably, there will be one shutter in the shutter array for each well  32 . The selector functions to block all of the wells  32  from emitting light onto the lens  56  and sensor  50 , except for one well  32 . In other words, the selector functions to permit one well  32  at a time to be tested. Thus, in the preferred embodiment where there five wells  52 , the selector will expose the first well  32  to the lens  56 , but bock all of the others until the test result from the first well  32  is obtained. The selector will then block the first well  32 , and expose the second well  32 , and repeat the process. This process is then repeated for each of the third, fourth and fifth wells. 
         [0060]    Thus, the selector, operatively connected to the micro-controller  46 , selects which well is being tested, and therefore, which pathogen is being tested for. Once the test associated with a particular well  32  is complete, and the test results obtained, the next well  32  is exposed, the test completed, and the test results obtained. 
         [0061]    It will be appreciated that the invention comprehends that there be no selector, but instead that the OSM be configured so that the light from each well  32  is emitted onto a separate light sensor  50 . However, it has been found that it is more cost and space efficient to have the selector which functions to select one well  32  at a time for obtaining a test result. 
         [0062]    The above disclosure is intended to be illustrative and not exhaustive. The description will suggest many variations and alternatives to one of ordinary skill in the art. All these alternatives and variations are intended to be included within the scope of the claims, in which the terms “comprise” and “include” mean “including, but not limited to.” 
         [0063]    Further, the particular features presented in the disclosure and the claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having other possible combinations of the features of the claims.