Abstract:
The present invention is directed to a luminometer and methods which provides simple and effective measurement of a plurality of wells in a plurality of strips in an automatic fashion. The luminometer may be used in CLIA (Chemi Luminescent Immuno Assays). The luminometer allows for CLIA micro strip reading, and reads break-apart wells, with a plurality of wells per strip, and calculates results instantly and automatically. The luminometer has an automatic carrier positioning system which selectively positions the plurality of wells in the plurality of strips at a measuring position, wherein the drive system associated with the positioning system drives the carrier along a single axis of movement. An optical track system automatically provides Y axis movement of the carrier. The luminometer may have a calibration system for maintaining proper operation of the system in measurements therewith.

Description:
TECHNICAL FIELD 
       [0001]    The present invention concerns a luminometer adapted for rapid assay of a plurality of small volume specimens, particularly in the field of medical assays. The invention also relates to methods of operation to acquire a plurality of assay measurements using the luminometer. 
       BACKGROUND OF THE INVENTION 
       [0002]    There are known luminometers permitting measurement of the light emitted during chemical reactions in specimens contained in plates, referred to as microtitration wells or plates. Systems have been developed to test specimen samples, such as blood samples for example, with an added reagent to the sample in a cuvette or microtitre plate. The reagent molecules reacts with and bind to certain components in the sample. The remainder of the sample is normally removed and a further reagent such as a base is added to cause parts of the bound molecules to luminesce. The reagent reaction time is normally an important parameter of the testing and incubation within strict time limits is required before a reacted sample is ready for luminescence detection. The intensity and spectral distribution of the emitted light is indicative of the concentration of the sample component being tested for. The light emissions may be fed through a spectral filter before application to the detector. Thus, with knowledge of the type of specimen sample, the type of reagent and the resultant spectral representation it is possible to determine the presence of certain chemicals in the specimen sample. Separate tests may be run with different reagents in the separate chambers to test for other constituents in the specimen. A luminometer detects and quantitates light emission, at the final step in a chemical reaction. The measurement is proportional to the analyte and so it can be used to make quantitative analysis. The advantage of using light (also called chemi-luminescence) is increased sensitivity. This is especially beneficial when looking for tumor markers, certain hormones, and the presence of toxins, contaminants, or drugs. 
         [0003]    As is also known, it is desirable to minimize the amount of background light which enters the measurement region of the luminometer. By minimizing the amount of background light from a luminescent signal which is descriptive of a sample&#39;s constituent concentration, assay results may be refined. 
         [0004]    In many environments, the testing of samples needs to be done efficiently to process a number of samples per hour. Complex systems for processing a large number of samples have been developed, but such systems are costly, large, difficult to use, and not suitable for many environments. It also is also important in acquiring proper results that the system be properly calibrated, and it would be desirable to provide a system which provides self-calibration to ensure proper operation. It would be desirable to provide a system which overcomes such limitations in prior devices. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an aspect of the present invention to overcome the drawbacks of the luminometers of the prior art by providing a system which provides a simple arrangement for the testing of multiple samples in a simple and effective manner. The invention provides an increased range and sensitivity, and is particularly useful in CLIA (Chemi Luminescent Immuno Assays). The luminometer allows for CLIA micro strip reading, and is useful for any size lab, and not just high volume labs. The luminometer reads break-apart wells, with a plurality of wells per strip, and calculates results instantly and automatically. The system may allow the user to program a wide variety of glow-type CLIA&#39;s, with tests capable of being stored for easy recall. Processing capabilities of the system may provide point-to-point, linear and log regressions, and log logit modes. It is also an aspect of the invention to provide a luminometer having a calibration system for maintaining proper operation of the system in measurements therewith. A further aspect of the invention relates to providing a light transmission system which allows for a compact and efficient system design. A further aspect of the invention relates to the ability to eliminate cross contamination of light in the operation of the device. The luminometer of the invention is a self-contained 3-strip CLIA (chemi-luminescent immuno assay) instrument. The microstrips contain wells designated for the blank, calibrator, controls, and specimens. The luminometer makes the readings (well by well) and then communicates the concentration of the analyte based on the calibrators. 
         [0006]    The luminometer according to the invention comprises a housing having an interior which is accessible through a closure door. A photon measuring and detection system is provided in the housing. An optical track is provided on a support within the housing with which a carrier is interfaced. The carrier has a plurality of wells provided therewith, with a predetermined measuring position associated with the detection system where each well is selectively positioned for measurement of photons therefrom. A drive system is provided to selectively displace the carrier along the optical track, being a system of track grooves which selectively move the carrier in X and Y directions to selectively position each well in the carrier in the measuring position. The luminometer may comprise suitable processing systems for amplifying and digitizing data and for processing the data. The luminometer may further comprise a reference light source for automatic calibration of the detection system. There may also be provided a carrier position detection system for ensuring proper positioning of the carrier in the optical track system. 
         [0007]    According to aspect of the invention, a calibration system is provided that comprises a reference light source positioned to emit light into a diffuser. A light detector is positioned to measure the light emitted from the diffuser, whereby a reference light signal is produced in association with the detection system. The reference light signal is thereafter comparable to the light subsequently detected from the same reference light source so as to allow generation of a calibration factor for any detected errors between a current measurement of the reference light source and the reference light signal. 
         [0008]    The invention also relates to a method of selectively moving a carrier in a predetermined manner in X-Y directions to selectively position a plurality of wells at a measuring position provided in a luminometer. More particularly, the method comprises the steps of positioning a carrier having a plurality of wells positioned therein at an initial position in association with a plurality of track grooves, wherein the carrier includes guide members which interface with the grooves to be movable along the grooves. The carrier is also interfaced with a drive system capable of allowing Y axis motion relative to the drive system, and for causing X axis movement of the carrier. The series of tracks includes portions directed along the X axis and connecting portions which provide movement of the carrier in the Y axis direction. The drive system moves the carrier along a single axis and the guide members associated with the carrier cause movement in the Y axis direction in conjunction with the connecting portions of the track system. 
         [0009]    There is also provided a method of calibrating a luminometer comprising the steps of providing a reference light source, and initially producing a reference measurement using the reference light source in conjunction with a light detector. Storing the reference measurement. Prior to introduction of new samples to be measured in the luminometer, turning on the reference light source and measuring the light emitted thereby to generate a current measurement. Comparing the current measurement with the reference measurement, and generating a calibration factor if the current measurement is different from the reference measurement by a predetermined amount, and applying the calibration factor to current measurements using the luminometer. 
         [0010]    Other aspects of the invention will become apparent upon reading of the following description in conjunction with the Figures herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The invention is described hereafter with respect to the accompanying drawings, on which are represented an embodiment of an automatic luminometer according to an example of the invention, showing: 
           [0012]      FIG. 1  shows a perspective view of an example of the luminometer according to the invention, with its cover, 
           [0013]      FIG. 2  shows a perspective view of various systems of the luminometer according to the invention, with the cover and other structures removed for clarity, 
           [0014]      FIG. 2A  shows a perspective view of the bottom of the carrier as shown in  FIG. 2 , 
           [0015]      FIG. 3  shows a top view of the optical track system for causing movement of the carrier along the X and Y axes, 
           [0016]      FIG. 4  is a side elevational view of the optical track system showing the well isolation system of an example of the invention, with portions removed for clarity, 
           [0017]      FIG. 5  is a perspective view of the optical detection system according to an example of the invention, and 
           [0018]      FIG. 6  shows an exploded partial view of a calibration system associated with an example of the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0019]    In  FIG. 1 , there is shown in perspective view of an example of the luminometer according to the invention. The luminometer  10  according to this example of the invention comprises a housing with the interior accessible through an entrance port  11  having a closure door or flap  13  associated therewith. The closure door  13  is designed to seal the interior of the housing where measurements are performed from any external light. A photon measurement detector is positioned in the housing, and a support platform for specimen carrier is provided. A system to selectively displace the carrier along X and Y axes, selectively moves the carrier to automatically perform measurements on a plurality of wells provided in the carrier. An electronic module for amplifying and digitizing data and for processing the data may be provided in the housing. In use, a carner having a plurality of microwells provided therein is introduced into the entrance port  11  for measurement of the samples contained therein. An LCD display  15  may be provided for presenting a readout of measured data, machine function or other information as desired. A plurality of switches or other suitable actuators  17  may be provided for controlling operation of the luminometer  10 . A printed record of measurement data may also be provided via an on-board graphics printing system  19 . 
         [0020]    With reference to the remaining FIGS., the systems are shown with the housing removed for clarity. As will be described hereafter, the systems include a strip isolation assembly  12  which extends over a reading area into which a strip carrier  14  is selectively moved for reading of a plurality of microstrips  16 . Typically, the format for immuno assays (all kinds) is a plate of 96 microwells (such as in a 12 by 8 array). Therefore other luminometers on the market are designed to handle this plate configuration. The luminometer according to this example instead reads micro-strips. The invention allows lower volume labs to use a more cost effective reader to do these tests in house instead of sending them out to bigger labs. The strips  16  have a plurality of microwells  18  into which a patient sample to be assayed is provided for reading in luminometer  10 . The luminometer  10  is usable for many different types of assays as desired. The user has a choice to load the microstrip carrier  14  with 1, 2, or 3 strips (either eight wells in length or twelve wells in length), or any number of separated wells. The strips are automatically pulled through the optical system using a unique optical track for enabling the carrier to index from row to row through the entire array of samples with only one linear axis of drive motion. Operation does not require manual movement of the strip from left to right. The optical track  22  which provides for proper movement of the carrier  14 . For simplicity of use, the measurements by the luminometer are always taken in a preprogrammed order. This allows data to be gathered in a systematic way for recording via appropriate software control of the systems and data acquisition and processing. As an example, the luminometer  10  may comprise on-board software to calculate RLU&#39;S, multi-point calibration and regression curves, as well as control of the operation of the device when performing measurements. The system may also comprise memory for storing measurement data, such as a non-volatile memory for storage of user-entered tests to allow easy use. The movement of the carrier  14  may be controlled by an encoder to precisely position a well  18  for reading in association with a detection system to be described hereafter, when the well is in alignment with the detection system. The detection system is centered on the microwell and all contamination of photons emitted by the adjacent microwells is removed as will be hereinafter described. With reference to  FIGS. 2 and 3 , there is shown the optical track  22  in more detail. The strip carrier  14  interfaces with a drive shuttle system  24  having a drive support block  26  carrying a drive pin  28 . The carrier  14  includes a drive groove  30  which is positioned to interface with drive pin  28 . The carrier  14  also includes front and rear guide pins  32  which are aligned in the optical track  22 , and more particularly in grooves  40  formed on optical track  22 . The optical track  22  provides a well indexing system, which moves the carrier  14  in a predetermined manner for automatic reading of a plurality of wells  18  in a plurality of strips  16  positioned in carrier  14 . The optical track provides a simple, but effective, system to selectively move the plurality of wells  18  into a reading position at  42 , where an aperture is provided in conjunction with the optical system  20  to read luminosity of the assay in each well  18 . The drive pin  28  moves the carrier  14  through the required motions to read each well  18  in each of the plurality of strips  16 , the optical track  22  provides two axes of motion (X,Y) with one mechanical axis of motion control provided by the drive shuttle system  24 . The shuttle block  26  is selectively moved along the edge of the optical track  22  in a linear motion by means of a drive system  50  comprising a motor  52  coupled to selectively drive a threaded rod  54  attached to the shuttle block  26 . Upon rotation of the threaded rod  54 , the shuttle block  26  is selectively moved in a linear motion as shown by arrow  56 . The motor  52  may be coupled to the threaded rod  54  via a drive belt  58  coupled to drive an encoder pulley  60 . The encoder pulley  60  is therefore selectively rotated by the drive motor  52  to in turn cause rotation of the threaded rod  54 , and corresponding movement of shuttle block  26 . The encoder pulley  60  comprises a plurality of apertures  62 , which are arranged to interface with an optical sensor system  64 , to allow precise movement of the encoder pulley  60  by motor  52 . This drive arrangement therefore allows precise indexing of the shuttle block  26  and drive pin  28 , and corresponding precise indexing of the strip carrier  14  interfaced therewith. 
         [0021]    The optical track  22  also allows for Y motion to be implemented for reading of the plurality of strips  16  positioned adjacent one another. As seen in  FIGS. 2 and 3 , the guide grooves  40  formed in optical track  22  include a plurality of tracks which interface with the guide pins  32  and  34  on carrier  14 . As seen in  FIG. 2A , the guide pins  32  and  34  are offset relative to one another, such that the front guide pin  32  will initially be positioned in one track groove  40  while the rear guide pin  34  is initially positioned in a different track groove  46 . In operation, upon driving the shuttle block  26  and drive pin  28 , the carrier will move linearly such that the first strip of wells is selectively moved to the reading position  42 . Upon reaching the end well of the first strip or row, the drive system continues to operate to move the carrier to one of the angled connecting grooves  48  provided a predetermined positions in the series of track grooves of the optical track  22 . The connecting grooves  48  provide for Y axis movement of the carrier  14 , which can slide relative to the drive pin  28  via mounting groove  30 . In this manner, the carrier  14  is automatically repositioned such that the second strip of wells is then situated along the path of the reading position  42 . The motor then reverses the direction of the drive system to read the second row of wells in reverse order. Similarly, after the last well  18  of the second row is read, the track sections  40  again provide for automatic Y axis movement of the carrier  14  via an angled connecting groove  48 , to position the third row of wells  18  along the path of the reading position  42 . After each of the remaining wells  18  are read, the drive system may then allow the carrier to change direction and return to the front of the luminometer  10  so that the user may remove the carrier  14  from the entrance port  11 , and repeat the process as needed. The optical track system  22  provides for desired X-Y movement of the carrier  14  in a simple arrangement, for precise positioning of each well  18  at the reading position  42 . 
         [0022]    In this example, the luminometer  10  is formed in a compact arrangement, making it easy to handle and use. The luminometer  10  in this example provides for continuous reading of up to three strips  16  of wells  18  continuously. The strip  16  may be either of an eight well or twelve well configuration, but other arrangements or number of wells are contemplated. The luminometer  10  has a length which is substantially equal to twice the dimension of the carrier  14 , providing a compact device. The strips  16  are first loaded into the carrier  14  and the carrier  14  is positioned on the optical track  20  on luminometer  10 . For reading of each well  18 , it is necessary to fully isolate the well from neighboring wells along with any external light. The strip isolation assembly  12  provides such function for proper reading of each well. As seen in  FIG. 4 , the strip isolation assembly  12  comprises a skid plate  60  under which the carrier  14  is moved during operation. The skid plate  60  is positioned on a guide bracket  61  which in turn is positioned on support posts  62  in association with screws  64  and biasing springs  66 . The biasing springs  66  allow limited upward movement of the skid plate  60  and guide bracket  61  as the carrier moves thereunder, while keeping a biasing force directed downwardly against the carrier  14  and wells  18  positioned therein. This ensures proper sealing of the skid plate  60  with each well at the reading position. The skid plate  60  is generally positioned at an angle so that the space thereunder is reduced from front to back, and the carrier  14  deflects the skid plate upwardly as it moves thereunder. The skid plate may have a front flange angled upwardly for smooth entrance of the carrier  14  thereunder. As an example, the movement of the strips  16  under the skid plate  60  may raise the skid plate approximately 0.025 inches, thereby creating a light-sealing surface at the top of each well  18  in the strips  16 . When the carrier  14  reaches the position for the reading of the first sample in the first well  18 , the skid plate seals all other wells so as to prevent cross-talk between the wells  18  during reading of each well  18 . A printed circuit board  63  carries electronic circuits for controlling operation of various components, and for controlling measurement processes and the like. 
         [0023]    Referring to  FIG. 5 , at the reading position  42  as previously described, the carrier  14  is positioned such that one well is positioned adjacent a fiber optic cable  70  mounted in association with a fiber optic mounting block  72 . The fiber optic  70  may be a 3.0 mm diameter solid core plastic fiber as an example, to effectively transport the light emitted from the patient sample to a photomultiplier  74 . The photomultiplier may be coupled to a detector system for measurement of emitted light from the sample in a known manner. The detector system may provide a rapid response time, sufficient measurement sensitivity, and be unaffected by magnetic and electromagnetic disturbances, or vibrations. The detector may have a low duration of remanance, to allow readings of a plurality of wells quickly. The interval of time between two measurements is of the order of seconds, by way of example. The fiber optic  70  is precisely positioned via the mounting block  72  to register with the reading well without cross talk or contamination by any external light source. 
         [0024]    To ensure proper registration and reading of the plurality of wells  18  in the desired sequence, the luminometer  10  may also have a position confirmation system to prevent mispositioning of the carrier when interfaced with the drive system. In this example, the carrier includes a reference or inspection hole  80  (see  FIG. 2A ) to ensure proper positioning of the carrier in the optical track. The hole  80  is used with a reference LED  82  as shown in  FIG. 6 , which is mounted under the optical track for example. Before reading a new collection of wells  18 , the carrier  14  is positioned on the optical track and moved into position for reading. At this time, the reference LED  82  is turned on, and a reading is taken. If the inspection hole  80  is in alignment with the fiber optic cable  70 , the carrier is mispositioned and rejected or conveyed back to the entrance port  11 , and the user must reposition the carrier  14 . If the carrier  14  is in its proper position, readings will automatically proceed. 
         [0025]    The luminometer  10  may also include an automatic calibration system to ensure proper reading therewith. As seen in  FIG. 6 , the reference LED  82  is positioned below and in alignment with the fiber optic cable  70 , the reference LED  70  may be an isolated circuit that emits a controlled and predetermined light along axis  90 , which can then be detected via the fiber optic  70  and detection system. For example, the reference LED  80  may emit a precise green light at 510 nm, or other suitable wavelength. The light is transmitted into a white nylon block  84 . The white nylon (or other suitable material) block  84  provides for uniform distribution of light emitted by the LED  82 . A photodiode  86  is mounted directly against the nylon block  84 . The photodiode  86  monitors the light emitted through the block and adjusts the input voltage to the LED  82 . This creates a closed loop system that regulates the intensity of the emitted light from the reference LED  82 . This system is mounted below the optical track, and the light from the reference LED  82  is transmitted through an aperture in the optical track, aligned directly below the input side of the fiber optic  70 , the LED  70  is selectively turned on or off during operation by a suitable control system. 
         [0026]    After a new luminometer is calibrated to a know standard, the reference LED  82  is turned on and a reading taken. The intensity of the LED is adjusted to a defined level. The final reading of the reference LED is stored in the luminometer for subsequent checking to ensure proper calibration before every use. Each time a new test is run using the luminometer  10 , the calibration can be checked by using the reference LED  82 , the device may automatically take a reading of the reference LED and if the new reading is not within a predetermined range about the stored final reading of the reference LED, a factor may be calculated to adjust all future readings accordingly. This will ensure the instrument continues to provide accurate results based on the initial calibration to a known standard. 
         [0027]    It should be noted that the invention provides a compact arrangement, and is simple and effectively used to perform luminosity measurements. The device provides for reliable measurements with high sensitivity as the detection of photons is carried out directly above the product well and amplified immediately afterward by means of the photomultiplier. The well isolation system provides eliminates possible light contamination, and the optical track system provides for simple and efficient movement of the carrier for automatically reading a plurality of wells quickly. The self-calibration and other attributes of the luminometer allow for an extremely cost-effective and simply used system as desired. While the invention has been described in conjunction with specific embodiments, it is evident that many alternatives, modifications, permutations and variations will become apparent to those of ordinary skill in the art in light of the foregoing description. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variations as fall within the scope of the appended claims.