Patent Publication Number: US-10775306-B2

Title: Modular testing device for analyzing biological samples

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a Continuation of U.S. application Ser. No. 15/561,901, filed Sep. 26, 2017, which is a 35 U.S.C. § 371 U.S. National Phase application of International Patent Application No. PCT/US2016/024260, filed Mar. 25, 2016, which claims the benefit of priority to U.S. Provisional Application No. 62/138,157, filed on Mar. 25, 2015, the disclosures of which are incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     The present invention relates to devices that are capable of analyzing biological samples, and in particular, to a modular testing device for analyzing biological samples. 
     Biological samples are typically tested in laboratories after the biological samples are collected in the field. A number of steps are taken to prepare the sample after it has been collected, including mixing the sample with reaction buffers, dyes, and any other chemical solutions needed to prepare the sample for testing. During or after sample preparation, testing equipment also needs to be prepared. This can include warming up the equipment, calibrating the equipment for the specific tests to be run, and running through any other initial procedures required for the specific testing equipment being used. Once the sample and the equipment are prepared, the prepared sample can be placed in the equipment for testing. 
     The typical process for testing biological samples described above has significant disadvantages. One disadvantage is that biological samples need to be collected in the field, brought into the laboratory, and then tested. This can present the following issues. One, the biological sample can be contaminated between the time when it was collected and time that it is to be tested. Two, it can be discovered that not enough biological sample was collected in the field, preventing the testing from being complete. Three, it can be later discovered that the biological samples that were taken are otherwise unsuitable for testing. When a biological sample is unsuitable for testing for any of the above reasons, an additional biological sample will need to be collected in order to complete the testing. This requires additional time, money, and other resources to complete. 
     To eliminate the problems discussed above, portable testing devices are available for analyzing biological samples in the field. One such device is disclosed in PCT Application No. PCT/US14/59487, filed on Oct. 7, 2014, and entitled “Portable Testing Device For Analyzing Biological Samples,” the disclosure of which is incorporated by reference in its entirety. In order to be portable, the testing devices need to be small enough so that they can be easily transported. This limitation on the size of portable testing devices limits the number of biological samples that can be tested at one time. 
     SUMMARY 
     A modular testing device includes a base unit and an expansion unit that communicates with the base unit. The expansion unit includes a housing, a receptacle in which a sample holder containing a biological sample and reagent mixture can be placed, and an optical assembly positioned in the housing. The optical assembly is configured to amplify and detect a signal from the biological sample and reagent mixture. Data that is collected in the optical assembly is communicated to the base unit. 
     A modular testing device includes a base unit and an expansion unit that communicates with the base unit. The base unit includes a housing with an integrated touchscreen display, a receptacle in which a sample holder containing a biological sample and reagent mixture can be placed, and an optical assembly positioned in the housing. The optical assembly is configured to amplify and detect a signal from the biological sample and reagent mixture. The expansion unit includes a housing, a receptacle in which a sample holder containing a biological sample and reagent mixture can be placed, and an optical assembly positioned in the housing. The optical assembly is configured to amplify and detect a signal from the biological sample and reagent mixture. 
     A method of analyzing a biological sample and reagent mixture in a modular testing device includes preparing a biological sample and reagent mixture for testing and placing the biological sample and reagent mixture in a sample holder. The sample holder is placed in a receptacle in an expansion unit. An excitation and detection test sequence is begun to analyze the biological sample and reagent mixture in the expansion unit. Data is collected from the excitation and detection test sequence in the expansion unit. The data is communicated from the expansion unit to a base unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a diagram of a first embodiment of a modular testing device including a base unit and an expansion unit. 
         FIG. 1B  is a diagram of a second embodiment of a modular testing device including a base unit and an expansion unit. 
         FIG. 1C  is a diagram of a third embodiment of a modular testing device including a base unit and an expansion unit. 
         FIG. 2A  is a perspective view of a base unit. 
         FIG. 2B  is a perspective view of the base unit when a sample holder in the form of a tube array is being placed in the base unit. 
         FIG. 3  is a block diagram of the base unit. 
         FIG. 4  is a perspective view of an expansion unit. 
         FIG. 5  is a block diagram of the expansion unit. 
         FIG. 6A  is a perspective view of an optical assembly. 
         FIG. 6B  is a cross-sectional view of the optical assembly. 
         FIG. 7  is an exploded view of a heating portion of the optical assembly. 
         FIG. 8  is an exploded view of a lens portion of the optical assembly. 
         FIG. 9  is an exploded view of a housing portion of the optical assembly. 
         FIG. 10A  is a partially exploded view of a first optical mounting portion of the optical assembly. 
         FIG. 10B  is a partially exploded view of a second optical mounting portion of the optical assembly. 
         FIG. 10C  is a partially exploded view of the first optical mounting portion and the second optical mounting portion of the optical assembly. 
         FIG. 11  is a flowchart showing steps for operating the modular testing device. 
     
    
    
     DETAILED DESCRIPTION 
     In general, the present disclosure relates to modular testing devices for analyzing biological samples. In the embodiments described below, the modular testing device is capable of testing biological samples with an isothermal amplification process, such as NEAR chemistry, LAMP chemistry, RPA chemistry, or NASBA chemistry. This eliminates the need for thermocycling as a means to amplify nucleic acid products for endpoint detection. 
       FIG. 1A  is a diagram of modular testing device  100  including base unit  102  and expansion units  106 .  FIG. 1B  is a diagram of modular testing device  100  including base unit  102  and expansion units  106 .  FIG. 1C  is a diagram of modular testing device  100  including base unit  104  and expansion units  106 . 
     Modular testing device  100  includes a base unit, including either base unit  102  or base unit  104 , and one or more expansion units  106 . In  FIGS. 1A-1B , modular testing device  100  is shown with base unit  102 . Base unit  102  can be used to analyze biological samples that have been mixed with a reaction mixture (also referred to as a biological sample and reagent mixture). Base unit  102  includes an optical assembly to amplify, excite, and detect a biological sample that is placed in base unit  102  for testing. Base unit  102  further includes a power supply to power base unit  102 , an electronic assembly including components that are capable of running test protocol, and a screen that a user can interface with to select parameters for the test protocol and which can display data as it is collected. In  FIG. 1C , modular testing device  100  is shown with base unit  104 . Base unit  104  is a desktop computer in the embodiment shown, but can be a laptop computer, tablet computer, a mobile phone, a smart watch, an embedded PC, or any other suitable computer in alternate embodiments. Base unit  104  includes a power supply to power base unit  104 , an electronic assembly including components that are capable of running test protocols, a machine readable code reader, and a screen that a user can interface with to select parameters for the test protocol and which can display data as it is collected. 
     In the embodiment shown in  FIGS. 1A-1C , three expansion units  106  are shown. In alternative embodiments, any number of expansion units  106  can be used. Each expansion unit  106  includes an optical assembly to amplify, excite, and detect a biological sample that is placed in base unit  102  for testing. In the embodiment shown in  FIGS. 1A-1C , each expansion unit  106  further includes a power supply to power expansion unit  106 . In an alternate embodiment, expansion unit  106  does not have a power supply but is instead powered by a base unit. Each expansion unit  106  further includes an electronic assembly including components that are capable of communicating data to the base unit. Each expansion unit  106  interfaces with and is controlled by the base unit, either base unit  102  or base unit  104 . The base unit communicates with expansion units  106  to indicate what testing is to be run in expansion units  106  and when testing is to be initiated. Expansion units  106  can be connected to the base unit with a hard wire connection or expansion units  106  can be connected to the base unit with a wireless connection. Testing can be completed in each expansion unit  106  using the optical assembly and data collected during the testing is communicated to the base unit. The data can be processed in expansion units  106  before it is communicated to the base unit or it can be communicated to the base unit before being processed. Either way, the data can also be processed in the base unit. 
     In the embodiments shown in  FIGS. 1A and 1C , a first expansion unit  106  is connected to the base unit, a second expansion unit  106  is connected to the first expansion unit  106 , and a third expansion unit  106  is connected to the second expansion unit  106 . In the embodiment shown in  FIG. 1B , expansion units  106  are each connected to the base unit. Further, in alternate embodiments, expansion units  106  can be connected to one another or the base units can be connected to one another. In one embodiment, for example, a first base unit  102  could be connected to a second base unit  102 . The first base unit  102  could communicate to the second base unit  102  what testing to run and when to initiate testing. The first base unit  102  and the second base unit  102  could conduct testing at the same time or at different times. In each of  FIGS. 1A-1C , expansion units  106  and the base units can be connected using a hardwire connection or a wireless connection. 
     Expansion units  106  can conduct testing of a biological sample at the same time or at different times. For example, each expansion unit  106  can be loaded with a biological sample. The base unit can then indicate to each expansion unit  106  that testing is to begin at the same time. Alternately, a first expansion unit  106  can be loaded with a biological sample and the base unit can indicate that the first expansion unit  106  is to begin testing. A second expansion unit  106  can then be loaded with a biological sample and the base unit can then indicate that the second expansion unit  106  is to begin testing. 
     Expansion units  106  can test a biological sample using turbidity, fluorescence, chemiluminescence, thermoluminescence, photometric, absorbance, or radiometric means. Expansion units  106  can also run different analytical methods, for example immunoassay, DNA amplification, mass spectrometry, or high-performance liquid chromatography. A single base unit can control expansion units  106  that are using different tests and running different analytical methods. 
     Modular testing device  100  is advantageous, as it allows a user to customize its modular testing device  100  for different applications. Expansion units  106  can be used with base unit  102  when a user wants to conduct testing in the field. Expansion units  106  can also then be used with base unit  104  when a user is conducting testing in a laboratory setting. Expansion units  106  also allow a user to customize how many tests are run during a testing protocol. Modular testing device  100  can also include a rack that is capable of holding expansion units  106 . The rack can be designed to fit over the base unit so that expansion units  106  can be positioned on the rack over the base unit. 
       FIG. 2A  is a perspective view of base unit  102 .  FIG. 2B  is a perspective view of base unit  102  when a sample holder in the form of tube array  108  is being placed in base unit  102 . Base unit  102  includes housing  110  (including first housing portion  112  and second housing portion  114 ), display  116 , handle  118 , lid  120 , receptacle  122  (shown in  FIG. 2B ), and optical assembly  124  (shown in  FIG. 2B ).  FIG. 2B  also shows tube array  108 . 
     Base unit  102  is used to analyze biological samples that have been mixed with a reaction mixture (also referred to as a biological sample and reagent mixture). Housing  110  forms the body of base unit  102 . Housing  110  includes first housing portion  112  and second housing portion  114 . First housing portion  112  forms a base portion of base unit  102  and second housing portion  114  forms a top portion of base unit  102 . Located on a front top side of housing  110  is display  116 . Display  116  is a touchscreen display in the embodiment shown, but can be any suitable display in alternate embodiments. A user can use display  116  to select test protocol and set up the parameters for tests that will be run in base unit  102 . A user can also use display  116  to provide sample and assay traceability information to base unit  102 . Display  116  will also display data that is collected during testing. 
     Housing  110  further includes handle  118 . Handle  118  is located on a front side of housing  110  in the embodiment shown, but can be located in any suitable location in alternate embodiments. Handle  118  is shown as an integrated handle with housing  110  in the embodiment shown, but can be attached to base unit  102  in any suitable manner in alternate embodiments. Handle  118  is included on base unit  102  so that base unit  102  can be easily transported in the field. 
     As seen in  FIG. 2B , receptacle  122  is located on a top side of base unit  102  in the embodiment shown, but can be located in any suitable location in alternate embodiments. Receptacle  122  is an opening in housing  110  of base unit  102 . A sample holder containing a biological sample and reagent mixture can be placed in receptacle  122  for testing. In  FIG. 2B , receptacle  122  is configured to receive tube array  108 . In alternate embodiments, receptacle  122  can be configured in any manner that is capable of receiving a sample holder. 
     Housing  110  also includes lid  120 . Lid  120  is located on a top side of housing  110  in the embodiment shown, but can be located in any suitable location in alternate embodiments. Lid  120  is included on base unit  102  to cover receptacle  122 . When a sample holder is placed in receptacle  122  of base unit  102  it will be positioned in optical assembly  124  that is held in base unit  102 . Optical assembly  124  is positioned just below receptacle  122  and can be accessed through receptacle  122 . Optical assembly  124  will be able to amplify, excite, and detect the biological sample in the sample holder. Optical assembly  124  includes a heating component that is used to heat the biological sample, causing it to amplify. The heating component can heat the biological sample at a constant temperature or the heating component can cycle the biological sample through different temperatures. Optical assembly  124  will then use radiation to excite the biological sample, so that the biological sample with emit radiation. 
     Lid  120  is positioned over receptacle  122  to prevent radiation from escaping housing  110  through receptacle  122 . Lid  120  further prevents ambient light from entering housing  110  through receptacle  122 , which prevents the ambient light from skewing or negating results of the tests that are being run in base unit  102 . Lid  120  also covers receptacle  122  to prevent contamination from entering into receptacle  122  when base unit  102  is being used in the field. Lid  120  is capable of being moved between an open and closed position and can be held in the closed position with any suitable means. In the embodiment shown, lid  120  is held in a closed position with magnets. When lid  120  is in an open position, sample holders (including tube array  108 ) can be inserted into and removed from receptacle  122 . When lid  120  is closed, sample holders will be held in receptacle  122  and radiation in base unit  102  will not escape from housing  110 . When lid  120  is in a closed position, it puts pressure on the sample holder that is placed in a heat block in base unit  102 . This improves engagement and heat transfer between the sample holder and the heat block in base unit  102 . 
     Receptacle  122  can be shaped to receive any sample holder, allowing base unit  102  to be designed to accommodate a wide variety of standard and custom designed sample holders. Tube array  108  is a standard sample holder that is widely available on the market. A card can also be custom designed for use as a sample holder that is to be used with base unit  102 . Receptacle  122  allows base unit  102  to be designed to accommodate a wide variety of sample holder shapes and sizes. 
     Base unit  102  is designed for use in the field and provides many advantages for such use. Biological materials that are collected in the field can be tested in the field as they are collected. This alleviates concerns about contamination or degradation of the biological sample, as there is no need to transport the biological sample back to a laboratory for testing. Further, base unit  102  allows a user to quickly react to results from tests that are run in the field. If a test is inconclusive, additional biological material can be collected and sampled right away. Further, if testing indicates that there is a pathogen or toxin in the sample, a user can initiate proper safety protocol right away to protect against the pathogen or toxin. 
     Base unit  102  includes a number of features that make it suitable for use in the field. Handle  118  is included to easily transport the device. Display  116  is integrated into base unit  102  so that base unit  102  can act as an all-in-one system, as base unit  102  is capable of testing a biological sample, processing the data that is collected, and displaying the data on display  116 . Display  116  eliminates the need for base unit  102  to be connected to another machine or computer to process and display the results of testing. This can allow a user to avoid having to carry an additional device in the field or having to wait till they get back to a laboratory to read the data. Base unit  102  includes all of the features that are necessary for testing, processing, and displaying results of the tests in a compact all-in-one device. 
       FIG. 3  is a block diagram of base unit  102 . Base unit  102  includes display  116 , power supply  130 , electronic assembly  132 , machine readable code reader  134 , and optical assembly  124 . Optical assembly  124  includes heat block  140 , light-emitting diodes  142 , and photodetectors  144 . 
     Base unit  102  is used to analyze and obtain data from biological samples in the field. To accomplish this, base unit  102  is equipped with display  116 , power supply  130 , electronic assembly  132 , machine readable code reader  134 , and optical assembly  124 . In the embodiment shown, display  116  is a touchscreen display that acts as a primary user interface between a user and base unit  102 . A user can input information into display  116  to indicate what testing should be run in base unit  102  for each biological sample. Further, a user can monitor the results of tests that are run in base unit  102  on display  116 . 
     Display  116  is connected to electronic assembly  132  with interface circuitry. Information that is inputted into display  116  will be communicated to electronic assembly  132  using the interface circuitry. Electronic assembly  132  includes hardware, firmware, and software to control the operations of base unit  102 , including a microprocessor. Electronic assembly  132  will indicate what testing is to be run in base unit  102  and communicates this information throughout the device. Data that is collected in base unit  102  during testing will also be communicated to electronic assembly  132 . Electronic assembly  132  can process this data and transmit it to display  116  to be displayed. Electronic assembly  132  further stores this data for retrieval or transfer at a later time. 
     Electronic assembly  132  is connected to power supply  130  with interface circuitry. Power supply  130  includes components that are capable of powering base unit  102 , including a battery, a power board, a power switch, and a power jack that can be connected to a power source for recharging. Power from power supply  130  is sent to electronic assembly  132  through the interface circuitry so that base unit  102  can operate. 
     Base unit  102  can further include machine readable code reader  134 . When a sample holder containing a machine readable code is placed in base unit  102 , machine readable code reader  134  can read the machine readable code on the sample holder. A machine readable code can also be provided separate from the sample holder. The machine readable code can contain all of the parameters for the testing protocol and the assay traceability information for the test that is to be run. Alternatively, the machine readable code can indicate what test is to be run. This is advantageous, as it allows a user to insert a sample into base unit  102  and base unit  102  will automatically select a test protocol and begin testing. 
     Electronic assembly  132  includes a microprocessor, associated memory, and interface circuitry for interfacing with display  116  and optical assembly  124 . Input that is received in electronic assembly  132  from display  116  can be processed in electronic assembly  132 . This information can be used to control optical assembly  124 . Optical assembly  124  conducts testing of the biological sample that is placed in base unit  102 . As the testing is being completed, data that is collected in optical assembly  124  can be communicated to electronic assembly  132 . Electronic assembly  132  processes this data and can transmit the data to display  116  so that the user can monitor the test results. Electronic assembly  132  can also transmit the data to an external device with any suitable data transfer means, including wireless transfer or transfer through a USB port, microUSB port, SD card, or microSD card. 
     Optical assembly  124  includes heat block  140 , light-emitting diodes  142 , and photodetectors  144  to conduct testing of the biological samples that are placed in base unit  102 . Optical assembly  124  will amplify the biological sample using heat and will then excite the biological sample with radiation to detect the presence of a specific fluorescent marker. Biological samples that are placed in base unit  102  will be mixed with a reaction mixture that contains one or more fluorescent dyes. When the biological sample is placed in base unit  102 , heat block  140  will amplify the biological sample with heat. Heat block  140  is positioned underneath receptacle  122  in base unit  102  so that when a sample holder containing a biological sample is placed in base unit  102 , the sample holder will be positioned in heat block  140 . As the biological sample is amplified it can be analyzed using light-emitting diodes  142  and photodetectors  144 . Light-emitting diodes  142  transmit radiation to the biological sample to excite the biological sample. A plurality of light-emitting diodes  142  can be used in base unit  102  to excite the biological sample at a predetermined cycle rate. In the embodiment shown, the plurality of light-emitting diodes  142  cycle on and off at 1.54 kHz. In alternate embodiments, light-emitting diodes  142  can cycle at any predetermined cycle rate. When the biological sample is excited at the predetermined cycle rate, it will emit radiation at the same predetermined cycle rate and the corresponding wavelengths of the fluorescent dyes that were added to the biological sample. This radiation can be received by photodetectors  144 . A plurality of photodetectors  144  can be used in base unit  102  to read the emitted radiation from the biological sample at different radiation wavelengths. The signals produced by photodetectors  144  can then be transmitted to electronic assembly  132  for processing and analysis, and displayed on display  116  as data collected during testing. 
     Base unit  102  is advantageous, as it is an all-in-one device. Base unit  102  includes optical assembly  124  to conduct testing of biological samples in the field. Base unit  102  further includes electronic assembly  132  and display  116  to specify what testing to run and to process and display data that is collected during testing. Base unit  102  further includes power supply  130 , including a battery, so that base unit  102  can be used in the field. Base unit  102  includes every component that is necessary to conduct testing of a biological sample, and does so in a compact device that can be easily used in the field. Using base unit  102  in the field prevents concerns about contamination or degradation of biological samples and allows a user to quickly react to test results in the field. 
       FIG. 4  is a perspective view of expansion unit  106 . Expansion unit  106  includes housing  150  (including first housing portion  152  and second housing portion  154 ), lid  156 , receptacle  158 , and optical assembly  124 . 
     Expansion unit  106  is used to analyze biological samples that have been mixed with a reaction mixture (also referred to as a biological sample and reagent mixture). Housing  150  forms the body of expansion unit  106 . Housing  150  includes first housing portion  152  and second housing portion  154 . First housing portion  152  forms a base portion of expansion unit  106  and second housing portion  154  forms a top portion of expansion unit  106 . Expansion unit  106  further includes lid  156 . 
     Receptacle  158  is located on a top side of expansion unit  106  in the embodiment shown, but can be located in any suitable location in alternate embodiments. Receptacle  158  is an opening in housing  150  of expansion unit  106 . A sample holder containing a biological sample can be placed in receptacle  158  for testing. In the embodiment shown, receptacle  158  is configured to receive tube array  108  (not shown in  FIG. 4 ). In alternate embodiments, receptacle  158  can be configured in any manner that is capable of receiving a sample holder. 
     Housing  150  also includes lid  156 . Lid  156  is located on a top side of housing  150  in the embodiment shown, but can be located in any suitable location in alternate embodiments. Lid  150  is included on expansion unit  106  to cover receptacle  158 . When a sample holder is placed in receptacle  158  of expansion unit  106  it will be positioned in optical assembly  124  that is held in expansion unit  106 . Optical assembly  124  is positioned just below receptacle  158  and can be accessed through receptacle  158 . Optical assembly  124  will be able to amplify, excite, and detect the biological sample in the sample holder. In the embodiment shown in  FIG. 4 , optical assembly  124  includes a heating component and detection components. The heating component is used to heat the biological sample, causing it to amplify. The heating component can heat the biological sample at a constant temperature or the heating component can cycle the biological sample through different temperatures. Optical assembly  124  will then use radiation to excite the biological sample, so that the biological sample with emit radiation which can then be detected by the detection components. In alternate embodiments, expansion unit  106  can include only a heating component or only detection components. Further, the heating component can heat the biological sample at a constant temperature, the heating component can cool the biological sample at a constant temperature, or the heating component can cycle the biological sample through a cycle of different temperatures. 
     Lid  156  is positioned over receptacle  158  to prevent radiation from escaping housing  150  through receptacle  158 . Lid  156  further prevents ambient light from entering housing  150  through receptacle  158 , which prevents the ambient light from skewing or negating results of the tests that are being run in expansion unit  106 . Lid  156  also covers receptacle  158  to prevent contamination from entering into receptacle  158  when expansion unit  106  is being used in the field. Lid  156  is capable of being moved between an open and closed position and can be held in the closed position with any suitable means. When lid  156  is in an open position, sample holders (including tube array  108 ) can be inserted into and removed from receptacle  158 . When lid  156  is closed, sample holders will be held in receptacle  158  and radiation in expansion unit  106  will not escape from housing  150 . When lid  156  is in a closed position, it puts pressure on the sample holder that is placed in a heat block in expansion unit  106 . This improves engagement and heat transfer between the sample holder and the heat block in expansion unit  106 . 
     Receptacle  158  can be shaped to receive any sample holder, allowing expansion unit  106  to be designed to accommodate a wide variety of standard and custom designed sample holders. Tube array  108  is a standard sample holder that is widely available on the market. A card can also be custom designed for use as a sample holder that is to be used with expansion unit  106 . Receptacle  158  allows expansion unit  106  to be designed to accommodate a wide variety of sample holder shapes and sizes. 
     Expansion unit  106  is advantageous, as it allows a user to increase the amount of tests the user is running in any given situation. Expansion unit  106  can be used in a laboratory setting or in the field. Expansion unit  106  can interface with a base unit, where the base unit indicates what testing the expansion unit  106  should conduct and when the testing should begin. Once data is collected in expansion unit  106 , it can be communicated to the base unit. The data can be processed in expansion unit  106  before it is communicated to the base unit or it can be communicated to the base unit without being processed. The base unit can then run the test protocol to process the data. 
       FIG. 5  is a block diagram of expansion unit  106 . Expansion unit  106  includes power supply  160 , electronic assembly  162 , and optical assembly  124 . Optical assembly  124  includes heat block  140 , light-emitting diodes  142 , and photodetectors  144 . 
     Expansion unit  106  is used to analyze and obtain data from biological samples. To accomplish this, expansion unit  106  is equipped with power supply  160 , electronic assembly  162 , and optical assembly  124 . Electronic assembly  162  includes hardware, firmware, and software to control the operations of expansion unit  106 , including a microprocessor. Electronic assembly  162  also includes a communication interface that communicates with an electronic assembly in the base unit. The communication interface can be a hard wire interface or a wireless interface. The wireless interface can communicate via Bluetooth, Wi-Fi, Infrared, or any other wireless technology. 
     The electronic assembly in the base unit will indicate what testing is to be run in expansion unit  106  and will communicates this information to electronic assembly  162  in expansion unit  106 . Data that is collected in expansion unit  106  during testing will be communicated to electronic assembly  162  in expansion unit  106 . Electronic assembly  162  in expansion unit  106  will then communicate the data to the electronic assembly in the base unit. Data can be processed in expansion unit  106  before it is communicated to the base unit or it can be communicated to the base unit without being processed. The electronic assembly in the base unit can also process this data and transmit it to a display to be displayed. The electronic assembly in the base unit also stores this data for retrieval or transfer at a later time. 
     In one embodiment, expansion unit  106  could be docked to a base unit through hard wire interface circuitry. When expansion unit  106  is docked to the base unit, the base unit can provide instructions to expansion unit  106  through the hard wire interface circuitry. Expansion unit  106  can then be removed from the base unit and used to run tests. After testing is completed, expansion unit  106  can be docked to the base unit through the hard wire interface circuitry again to communicate the data collected during the testing to the base unit. In a second embodiment, expansion unit  106  can receive instructions from a base unit wirelessly by utilizing wireless interface circuitry. Expansion unit  106  can then be used to run tests. After testing is completed, expansion unit  106  can be docked to the base unit through hard wire interface circuitry to communicate the data collected during the testing to the base unit. 
     Electronic assembly  162  is connected to power supply  160  with interface circuitry. In the embodiment shown in  FIG. 5 , power supply  160  includes components that are capable of powering expansion unit  106 , including a battery, a power board, a power switch, and a power jack that can be connected to a power source for recharging. Power from power supply  160  is sent to electronic assembly  162  through the interface circuitry so that expansion unit  106  can operate. In an alternate embodiment, expansion unit  106  can be powered by a base unit and power supply  160  will include a power jack that can be connected to the base unit to provide power to expansion unit  106 . 
     Electronic assembly  162  further includes a microprocessor, associated memory, and interface circuitry for interfacing with optical assembly  124 . Input that is received in electronic assembly  162  from the electronic assembly of the base unit can be processed in electronic assembly  162 . This information can be used to control optical assembly  124 . Optical assembly  124  conducts testing of the biological sample that is placed in expansion unit  106 . As the testing is being completed, data that is collected in optical assembly  124  can be communicated to electronic assembly  162 . Electronic assembly  162  processes this data and can transmit the data to the electronic assembly in the base unit. The electronic assembly in the base unit can then transmit the data to a display so that the user can monitor the test results. Electronic assembly  162  can also transmit the data to an external device with any suitable data transfer means, including wireless transfer or transfer through a USB port, microUSB port, SD card, or microSD card. 
     Optical assembly  124  includes heat block  140 , light-emitting diodes  142 , and photodetectors  144  to conduct testing of the biological samples that are placed in expansion unit  106 . Optical assembly  124  will amplify the biological sample using heat and will then excite the biological sample with radiation to detect the presence of a specific fluorescent marker. Biological samples that are placed in expansion unit  106  will be mixed with a reaction mixture that contains one or more fluorescent dyes. When the biological sample is placed in expansion unit  106 , heat block  140  will amplify the biological sample with heat. Heat block  140  is positioned underneath receptacle  158  in expansion unit  106  so that when a sample holder containing a biological sample is placed in expansion unit  106 , the sample holder will be positioned in heat block  140 . As the biological sample is amplified it can be analyzed using light-emitting diodes  142  and photodetectors  144 . Light-emitting diodes  142  transmit radiation to the biological sample to excite the biological sample. A plurality of light-emitting diodes  142  can be used in expansion unit  106  to excite the biological sample at a predetermined cycle rate. In the embodiment shown, the plurality of light-emitting diodes  142  cycle on and off at 1.54 kHz. In alternate embodiments, light-emitting diodes  142  can cycle at any predetermined cycle rate. When the biological sample is excited at the predetermined cycle rate, it will emit radiation at the same predetermined cycle rate and the corresponding wavelengths of the fluorescent dyes that were added to the biological sample. This radiation can be received by photodetectors  144 . A plurality of photodetectors  144  can be used in expansion unit  106  to read the emitted radiation from the biological sample at different radiation wavelengths. The signals produced by photodetectors  144  can then be transmitted to electronic assembly  162  for transmitting to the electronic assembly of the base unit. The electronic assembly of the base unit can then process and analyze the data, and display the data as the data is collected during testing. 
       FIG. 6A  is a perspective view of optical assembly  124 .  FIG. 6B  is a cross-sectional view of optical assembly  124 . Optical assembly  124  includes heating portion  170  (not shown in  FIG. 6A ), lens portion  172  (not shown in  FIG. 6A ), housing portion  174 , first optical mounting portion  176 , and second optical mounting portion  178 . Also shown in  FIG. 6B  is tube array  108 . 
     Optical assembly  124  can be positioned in both base unit  102  and expansion units  106 . Optical assembly  124  includes heating portion  170  to heat the biological sample and reagent mixture in tube array  108 . Positioned in heating portion  170  is lens portion  172  to direct radiation through optical assembly  124 . Housing portion  174  is positioned around heating portion  170  and forms the main body portion of optical assembly  124 . First optical mounting portion  176  is positioned on a first side of housing portion  174  and second optical mounting portion  178  is positioned on a second side of housing portion  174 . Both first optical mounting portion  176  and second optical mounting portion  178  mount light-emitting diodes to optical assembly  124  to excite the biological sample and reagent mixture in tube array  108 . Further, both first optical mounting portion  176  and second optical mounting portion  178  mount photodetectors to optical assembly  124  to detect a signal from the biological sample and reagent mixture in tube array  108 . 
       FIG. 7  is an exploded view of heating portion  170  of optical assembly  124 . As seen in  FIGS. 6B and 7 , heating portion  170  includes sample block  190 , heating component  192 , temperature sensor  194 , wells  196 , passages  198 , passages  200 , passages  202 , and passages  204 . 
     Heating portion  170  includes sample block  190  that forms the main body portion of heating portion  170 . Heating component  192  is attached to a second side of sample block  190 . Heating component  192  is a flat polyimide heater in the embodiment shown, but can be any suitable heater in alternate embodiments. Temperature sensor  194  is placed in a bottom portion of sample block  190  to sense the temperature of sample block  190 . Further, in alternate embodiments, a thermal cut out switch, such as a PEPI switch, can be placed in series with a lead on heating component  192 . 
     Sample block  190  includes wells  196  on a top side of sample block  190 . Each well  196  is sized to receive one tube in tube array  108 . In the embodiment shown in  FIG. 7 , heating component  192  heats each of wells  196  at a constant temperature so that modular testing device  100  can be used with isothermal amplification chemistries. In alternate embodiments, heating component  192  can heat each well  196  at a different temperature across a gradient, or there can be a plurality of heating components so that each well is heated by a different heating component to a different temperature. This allows a user to conduct a preliminary test to determine what temperature should be used to analyze a particular biological sample. In further alternate embodiments, heating component  192  can include a thermal cycler that is capable of cycling heating portion  170  through different temperatures so that modular testing device  100  can be used with non-isothermal polymerase chain reaction (PCR) chemistries. 
     Sample block  190  further includes passages  198 , passages  200 , passages  202 , and passages  204 . Passages  198  extend from a first side of sample block  190  to wells  196 . Passages  200  extending from a bottom side of sample block  190  to wells  196 . Passages  202  extend from the second side of sample block  190  to wells  196 . Passages  204  extend from a bottom side of sample block  190  to wells  196 . Passages  198 , passages  200 , passages  202 , and passages  204  extend through sample block  190  to direct radiation into and out of the biological sample and reagent mixture in tube array  108  in wells  196 . 
       FIG. 8  is an exploded view of lens portion  172  of optical assembly  124 . As seen in  FIGS. 6B and 8 , lens portion  172  includes lenses  210  and lens retainer  212 . 
     Lens portion  172  includes lenses  210  that are positioned in sample block  190  of heating portion  170 . Passages  198  in sample block  190  are sized to receive lenses  210  on the first side of sample block  190 . One lens  210  is positioned in each passage  198  of sample block  190 . Lenses  210  are held in passages  198  with lens retainer  212 . Lens retainer  212  has a plurality of apertures so that radiation can pass through lens retainer  212  to pass through lenses  210 . 
       FIG. 9  is an exploded view of housing portion  174  of optical assembly  124 . As seen in  FIGS. 6A-6B and 9 , housing portion  174  includes first housing  220 , second housing  222 , heat shield  224 , passages  226 , passages  228 , passages  230 , passages  232 , and apertures  234 . 
     Housing portion  174  includes first housing  220  positioned on a first side of heating portion  170  and second housing  222  positioned on a second side of heating portion  170 . First housing  220  and second housing  222  form a main body portion of housing portion  174 . Heat shield  224  is positioned between first housing  220  and second housing  222  on a top side of heating portion  170 . 
     First housing  220  includes passages  226  and passages  228 . Passages  226  extend from a first side of first housing  220  to an interior side of first housing  220  adjacent sample block  190 . Each passage  226  in first housing  220  is aligned with one passage  198  in sample block  190 . Passages  228  extend from a bottom side of first housing  220  to an interior side of first housing  220  adjacent sample block  190 . Each passage  228  in first housing  220  is aligned with one passage  200  in sample block  190 . Passages  226  and  228  extend through first housing  220  to direct radiation into and out of the biological sample and reagent mixture in tube array  108  in wells  196  of sample block  190 . 
     Second housing  222  includes passages  230  and passages  232 . Passages  230  extend from a second side of second housing  222  to an interior side of second housing  222  adjacent sample block  190 . Each passage  230  in second housing  222  is aligned with one passage  202  in sample block  190 . Passages  232  extend from a bottom side of second housing  222  to an interior side of second housing  222  adjacent sample block  190 . Each passage  232  in second housing  222  is aligned with one passage  204  in sample block  190 . Passages  230  and  232  extend through second housing  222  to direct radiation into and out of the biological sample and reagent mixture in tube array  108  in wells  196  of sample block  190 . 
     Heat shield  224  is positioned over sample block  190  and held between first housing  220  and second housing  222 . Apertures  234  extend from a top side to a bottom side of heat shield  224 . Each aperture  234  in heat shield  224  is aligned with one well  196  in sample block  190 . This allows tube array  108  to be positioned in wells  196  in sample block  190  through apertures  234  in heat shield  224 . Heat shield  224  is positioned over sample block  190  to prevent heat from escaping out of the top side of sample block  190 . Heat shield  224  further provides an insulated surface to protect the user from the top side of sample block  190  when sample block  190  is hot. 
       FIG. 10A  is a partially exploded view of first optical mounting portion  176  of optical assembly  124 .  FIG. 10B  is a partially exploded view of second optical mounting portion  178  of optical assembly  124 .  FIG. 10C  is a partially exploded view of first optical mounting portion  176  and second optical mounting portion  178  of optical assembly  124 . As seen in  FIGS. 6A-6B, 10A, and 10C , first optical mounting portion  176  includes housing  240 , housing  242 , emission filter  244 , gasket  246 , excitation filter  248 , passages  250 , passages  252 , photodetectors mounting board  254 , photodetectors  256 , gasket  258 , light-emitting diodes mounting board  260 , light-emitting diodes  262 , and gasket  264 . As seen in  FIGS. 6A-6B and 10B-10C , second optical mounting portion  178  includes housing  270 , housing  272 , emission filter  274 , gasket  276 , excitation filter  278 , passages  280 , passages  282 , photodetectors mounting board  284 , photodetectors  286 , gasket  288 , light-emitting diodes mounting board  290 , light-emitting diodes  292 , and gasket  294 . 
     First optical mounting portion  176  is positioned on a first side of housing portion  174 . First optical mounting portion  176  includes housing  240  and housing  242  that form a main body portion of first optical mounting portion  176 . Housing  240  is attached to a first side of first housing  220  of housing portion  174 . Emission filter  244  is positioned between housing  240  and first housing  220  in a groove on the first side of first housing  220 . Gasket  246  is positioned between emission filter  244  and housing  240 . Housing  242  is attached to a bottom side of first housing  220  of housing portion  174 . Excitation filter  248  is positioned between housing  242  and first housing  220  in a groove on the bottom side of first housing  220 . 
     Housing  240  includes passages  250 . Passages  250  extend from a first side of housing  240  to an interior side of housing  240  adjacent first housing  220 . Each passage  250  in housing  240  is aligned with one passage  226  in first housing  220 . Housing  242  includes passages  252 . Passages  252  extend from a bottom side of housing  252  to an interior side of housing  242  adjacent first housing  220 . Each passage  252  in housing  242  is aligned with one passage  228  in first housing  220 . 
     Photodetectors mounting board  254  is connected to a first side of housing  240 . Photodetectors mounting board  254  is an electronic board that includes photodetectors  256 . Each photodetector  256  on photodetectors mounting board  254  is positioned in one passage  250  in housing  240 . Gasket  258  is positioned between photodetectors mounting board  254  and housing  240 . Light-emitting diodes mounting board  260  is attached to a bottom side of housing  242 . Light-emitting diodes mounting board  260  is an electronic board that includes light-emitting diodes  262 . Each light-emitting diode  262  on light-emitting diodes mounting board  260  is positioned in one passage  252  in housing  242 . Gasket  264  is positioned between light-emitting diodes mounting board  260  and housing  242 . 
     Second optical mounting portion  178  is positioned on a second side of housing portion  174 . Second optical mounting portion  178  includes housing  270  and housing  272  that form a main body portion of second optical mounting portion  178 . Housing  270  is attached to a second side of second housing  222  of housing portion  174 . Emission filter  274  is positioned between housing  270  and second housing  222  in a groove on the second side of second housing  222 . Gasket  276  is positioned between emission filter  274  and housing  270 . Housing  272  is attached to a bottom side of second housing  222  of housing portion  174 . Excitation filter  278  is positioned between housing  272  and second housing  222  in a groove on the bottom side of second housing  222 . 
     Housing  270  includes passages  280 . Passages  280  extend from a second side of housing  270  to an interior side of housing  270  adjacent second housing  222 . Each passage  280  in housing  270  is aligned with one passage  230  in second housing  222 . Housing  272  includes passages  282 . Passages  282  extend from a bottom side of housing  282  to an interior side of housing  282  adjacent second housing  222 . Each passage  282  in housing  272  is aligned with one passage  232  in second housing  222 . 
     Photodetectors mounting board  284  is connected to a first side of housing  270 . Photodetectors mounting board  284  is an electronic board that includes photodetectors  286 . Each photodetector  286  on photodetectors mounting board  284  is positioned in one passage  280  in housing  270 . Gasket  288  is positioned between photodetectors mounting board  284  and housing  270 . Light-emitting diodes mounting board  290  is attached to a bottom side of housing  272 . Light-emitting diodes mounting board  290  is an electronic board that includes light-emitting diodes  292 . Each light-emitting diode  292  on light-emitting diodes mounting board  290  is positioned in one passage  282  in housing  272 . Gasket  294  is positioned between light-emitting diodes mounting board  290  and housing  272 . 
     As seen in  FIGS. 6A-10C , optical assembly  124  can excite and detect emissions from a biological sample and reagent mixture in tube array  108  that is positioned in optical assembly  124 . Light-emitting diodes  262  are bi-color light-emitting diodes that can emit radiation at two different wavelengths. In the embodiment shown, light-emitting diodes  262  are blue and amber bi-color light-emitting diodes to excite Fluorescein amidite (FAM) fluorescence dye and 6-Carboxyl-X-Rhodamine (ROX) fluorescence dye, respectively. Further, light-emitting diodes  262  emit radiation at a predetermine cycle rate of 1.54 kHz. Radiation from light-emitting diodes  262  can pass through passages  252 , excitation filter  248 , passages  228 , and passages  200  into the biological sample and reagent mixture in tube array  108  that is held in wells  196 . Excitation filter  248  is a dual bandpass excitation filter that is capable of passing either of the wavelengths emitted by light-emitting diodes  262 . Excitation filter  248  is a single filter that extends across the entire length of tube array  108 , thus excitation filter  248  extends between adjacent passages  228  in first housing  220 . Radiation from light-emitting didoes  262  can excite a fluorescent dye in the biological sample and reagent mixture. This excitation of the fluorescent dye will emit a signal from the biological sample and reagent mixture and the emission can pass through passages  198 , passages  226 , emission filter  244 , and passages  250  to be detected by photodetectors  256 . Emission filter  244  is a dual bandpass emission filter in the embodiment shown. Emission filter  244  is a single filter that extends across the entire length of tube array  108 , thus emission filter  244  extends between adjacent passages  226  in first housing  220 . 
     Light-emitting diodes  292  are light-emitting diodes that can emit radiation at a single wavelength spectrum. In the embodiment shown, light-emitting diodes  292  are green light-emitting diodes to excite 6-carboxy-X-hexachlorofluorescein (HEX) fluorescence dye. Further, light-emitting diodes  292  emit radiation at a predetermine cycle rate of 1.54 kHz. Radiation from light-emitting diodes  292  can pass through passages  282 , excitation filter  278 , passages  232 , and passages  204  into the biological sample and reagent mixture in tube array  108  that is held in wells  196 . Excitation filter  278  is a single bandpass filter that is capable of passing the wavelength emitted by light-emitting diodes  292 . Excitation filter  278  is a single filter that extends across the entire length of tube array  108 , thus excitation filter  278  extends between adjacent passages  232  in second housing  222 . Radiation from light-emitting didoes  292  can excite a fluorescent dye in the biological sample and reagent mixture. This excitation of the fluorescent dye will emit a signal from the biological sample and reagent mixture and the emission can pass through passages  202 , passages  230 , emission filter  274 , and passages  280  to be detected by photodetectors  286 . Emission filter  274  is a single bandpass filter in the embodiment shown. Emission filter  274  is a single filter that extends across the entire length of tube array  108 , thus emission filter  274  extends between adjacent passages  230  in second housing  222 . 
     In an alternate embodiment, light-emitting diodes  292  can be bi-color light-emitting diodes that can emit radiation at two different wavelengths. Further, excitation filter  278  can be a dual bandpass filter that is capable of passing both of the wavelengths emitted by light-emitting diodes  292 , and emission filter  274  can also be a dual bandpass filter. This would result in modular testing device  100  being capable of testing four different fluorescent dyes that can be mixed in with the biological sample and reagent mixture. 
     Light-emitting diodes  262  and light-emitting diodes  292  emit radiation in the form of light that is cycled at a predetermined rate of 1.54 kHz. This causes emissions from the biological sample and reagent mixture at the same predetermined rate. Photodetectors  256  and photodetectors  286  thus receive the emissions from the biological sample and reagent mixture at a rate of 1.54 kHz as well. The electronic circuitry connected to photodetectors  256  and photodetectors  286  is designed to electronically filter out all other frequencies except for 1.54 kHz. This will negate any ambient light or other radiation sources in modular testing device  100  that may interfere with the accuracy of the testing. 
     Having a single filter for emission filter  244 , excitation filter  248 , emission filter  274 , and excitation filter  278  simplifies the design of modular testing device  100 . This simplified design makes modular testing device  100  more suitable for use in the field. If one of emission filter  244 , excitation filter  248 , emission filter  274 , or excitation filter  278  had to be replaced, it would be easy to replace the entire filter instead of a number of different individual filters. Further, using one filter for each of emission filter  244 , excitation filter  248 , emission filter  274 , or excitation filter  278  reduces the cost of modular testing device  100 . 
       FIG. 11  is a flowchart showing steps for operating modular testing device  100 . The flowchart includes steps  300 - 316 . 
     Step  300  includes preparing a biological sample and reagent mixture for testing. The reagent mixture can contain the master mix necessary for the desired assay, including fluorescent dyes or markers such as FAM or ROX, necessary for detecting the desired analyte in modular testing device  100 . Once a user acquires a biological sample, the biological sample can then be mixed with a reagent to form a biological sample and reagent mixture. More specifically, the biological sample is first mixed with a reaction buffer. Next, a portion of the biological sample and reaction buffer mixture is transferred to a sample holder containing a dried down master mix. This forms the biological sample and reagent mixture for testing. The biological sample and reaction mixture can be tested in the sample holder containing the dried down master mix or transferred to a different sample holder for testing. 
     In step  302 , both the base unit and expansion unit  106  are turned on. In step  304 , a test protocol is selected in the base unit. This can be done by scanning a code with machine readable code reader  154 . The code will contain information about what test protocol is to be run and what parameters should be used. The test protocol can also be selected on the display of the base unit and the parameters can be inputted into the base unit. Step  306  includes communicating the selected test protocol from the base unit to expansion unit  106 . Expansion unit  106  can then begin heating to the required temperature for the selected test protocol. When expansion unit  106  is preheated, it can communicate with the base unit. The base unit will visually and audibly notify the user that expansion unit  106  is ready for testing. In step  308 , the user opens lid  156  of expansion unit  106  and places the sample holder with the biological sample and reagent mixture into heating assembly  170  in expansion unit  106 . 
     In step  310 , the user begins the excitation and detection sequence for the desired assay using the user interface on the display of the base unit. The base unit then communicates with expansion unit  106  to indicated to expansion unit  106  that testing can begin. Optical assembly  124  in expansion unit  106  then begins the excitation and detection sequence. Step  312  includes collecting data from the biologicals sample and reagent mixture in expansion unit  106  during the excitation and detection sequence. Step  314  includes communicating the data from expansion unit  106  to the base unit. Data is transmitted from optical assembly  124  to electronic assembly  162  in expansion unit  106 . The data can be processed by electronic assembly  162  in expansion unit  106  before being communicated to the base unit. Electronic assembly  162  in expansion unit  106  then communicates the data to an electronic assembly in the base unit. Step  316  includes processing the data in the base unit. The processed data can then be displayed in the base unit to the user. 
     Steps  312 ,  314 , and  316  can be done in real-time as data is being collected form the biological sample and reagent mixture in expansion unit  106 . The electronic assembly and the display in the base unit can also log the data received from expansion unit  106  and monitor the data for threshold activity. Once the assay is complete, the display signals a positive, negative, or indeterminate outcome to the user. The electronic assembly of the base unit can also store the data obtained for retrieval or transfer. 
     Steps  300 - 316  described above apply to both base unit  102  and base unit  104 . If base unit  102  is used, additional testing can be conducted in base unit  102  at the same time as testing is being conducted in expansion unit  106 . Base unit  102  can be preheated at the same time as expansion unit  106 , and lid  120  of base unit  102  can be opened so that a sample holder containing a biological sample and reagent mixture can be placed in heating assembly  10  of base unit  102 . Further, base unit  102  can begin the excitation and detection sequence for the desired assay at the same time as expansion unit  106  and data can be collected biological sample and reagent mixture in base unit  102 . Base unit  102  can display the data collected in base unit  102  and expansion unit  106  on display  116 . 
     While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.