Abstract:
A liquid storage apparatus provides a safe and easy to use device for efficiently managing liquid reagents used in a variety of laboratory equipment. The liquid storage apparatus helps reduce the likelihood of accidental sticks to laboratory personnel, allows for flexibility of experimental design, and helps maximize the use of chemical regents to prevent waste. The apparatus includes a plurality of containers of liquid with a pierceable septum interface at each end. The apparatus also includes a lower array of needles with each of the lower needles in the lower array of needles arranged to penetrate the bottom pierceable septum of a different one of the containers. Each of the needles includes a passage so the liquid can flow out of the pierced container. The apparatus further includes an upper array of needles with each of the upper needles in the upper array of needles arranged to penetrate the top pierceable septum of a different one of the containers. Each of the needles include a passage so gas can flow into the pierced container to occupy the space created as the liquid flows out of the container.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates generally to storing and handling liquid reagents for use in single molecule sequencing. 
       BACKGROUND INFORMATION 
       [0002]    Fluidic systems are used in a variety of areas including biochemical analysis, medical diagnostics, analytical chemistry, chemical synthesis, and environmental monitoring. Microfluidic systems provide certain advantages in acquiring chemical and biological information. For example, microfluidic systems permit complicated processes to be carried out using small amounts of reagents. 
         [0003]    In certain diagnostic equipment and systems, large numbers of various sized bottles of different liquid reagents are required. In these systems, liquids are typically stored in conventional bottles with a needle pierceable septum at one end. Fluids can be extracted from these bottles in several ways. For example, the septum can be pierced with a short or a long needle. The long needle is designed to reach the bottom of the bottle to extract the liquid, and the short needle provides an air vent to replace the liquid with air as it is extracted from the bottle. A long needle causes safety concerns and requires complex mechanisms to protect and guide into the bottle. Another example of a method for extracting the liquid from these bottles is to provide a significant air volume above the liquid to allow for low vacuum level build-up while extracting. This method has certain drawbacks as well because allowing even a small vacuum build-up in the bottle can introduce dispensing errors at selector valves in the liquid handling system. Furthermore, liquid storage systems and interfaces that use this method are difficult to manage. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention provides for liquid reagent storage and handling and can be used in conjunction with microfluidic volume analyzing equipment such as chemical analyzers and single molecule sequencing equipment. Generally, the invention provides a safe and easy way to manage efficiently liquid reagents for use in a variety of laboratory equipment. The present invention helps reduce the likelihood of accidental sticks to laboratory personnel, allows for flexibility of experimental design, and helps maximize the use of chemical reagents to prevent waste. 
         [0005]    In a particular embodiment, the invention features an apparatus comprising a plurality of containers. Each of the containers includes a liquid reagent, a top pierceable septum and a bottom pierceable septum. The apparatus also includes a lower array of needles. Each of the lower needles in the lower array of needles is arranged to penetrate the bottom pierceable septum of a different one of the containers and each of the needles include a passage so the liquid can flow out of the pierced container. The apparatus further includes an upper array of needles. Each of the upper needles in the upper array of needles is arranged to penetrate the top pierceable septum of a different one of the containers and each of the needles include a passage so gas can flow into the pierced container to occupy the space created as the liquid flows out of the container. 
         [0006]    In an alternative embodiment, a subset of two or more of the containers can be selectively secured together to form a cartridge assembly. One of more of these cartridge assemblies can be used to streamline or simplify the process of loading and unloading liquid reagents. A further aspect of this embodiment allows for customized cartridge assemblies designed for specific applications so that the liquid in each container of the cartridge is used up at approximately the same time. 
         [0007]    In another aspect of the invention, the lower array of needles includes non-coring needles with a closed sharpened end. These needles include an aperture in the side of the needle, which can be positioned slightly inside the bottom pierceable septum to maximize the utilization of the liquid reagents. 
         [0008]    In a further aspect of the invention, the upper array of needles is fluidly coupled to a filter, ventilation system, check valve or an inert gas system. For a variety of reasons it may be important to regulate the flow of gas into, or out of the containers as the liquids are being withdrawn. Some reagents may give off toxic fumes or unpleasant odors while others may degrade in the presence of oxygen. Providing a partially or completely sealed system can help provide a safer work environment and prevent the liquid reagents from breaking down or altering their composition. 
         [0009]    In yet another aspect of the invention, the liquid storage apparatus further includes a liquid level sensor. Analytical equipment utilizing the liquid reagents stored in the apparatus can be damaged if gasses are allowed to enter the other systems. One way of preventing this damage is to provide liquid level sensors for each individual container or for the entire apparatus that either notifies the user when the liquid level is getting low or shuts down the equipment. Various types of sensors can be used with the apparatus including, for example, ultrasonic, optical, capacitance level sensing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    For a fuller understanding of how to make and use a needle and container arrangement according to the invention, reference is made to the following description which should be taken in conjunction with the accompanying drawing figures wherein like reference characters denote corresponding parts throughout the several views and wherein: 
           [0011]      FIG. 1  is a schematic perspective view of an exemplary embodiment of a needle and container arrangement showing the containers in the process of being loaded; 
           [0012]      FIG. 2A  is a schematic perspective view of the needle and container arrangement of  FIG. 1  showing the containers in the loaded position; 
           [0013]      FIG. 2B  is an enlarged schematic perspective view of the needle and container arrangement of  FIG. 2A  showing the lower needles pierced through the bottom pierceable septum of two of the containers; 
           [0014]      FIG. 3A  is a schematic perspective view of a Trocar needle for use in the lower array of needles of the needle and container arrangement of  FIG. 1 ; 
           [0015]      FIG. 3B  is a schematic front view of the Trocar needle shown in  FIG. 3A ; 
           [0016]      FIG. 4A  is a schematic top view of a deflected tip needle for use in the upper array of needles of the needle and container arrangement of  FIG. 1 ; 
           [0017]      FIG. 4B  is a schematic front view of the deflected tip needle shown in  FIG. 4A ; 
           [0018]      FIG. 4C  is a schematic side view of the deflected tip needles shown in  FIG. 4A ; 
           [0019]      FIG. 5  is a schematic perspective view of the needle and container arrangement of  FIG. 1  showing the cover in a closed position; 
           [0020]      FIG. 6A  is a cross-section front view of an individual container of the needle and container arrangement of  FIG. 1  showing a lower needle pierced through the bottom pierceable septum; 
           [0021]      FIG. 6B  is a top view of an individual container of the needle and container arrangement of  FIG. 1 ; 
           [0022]      FIG. 7  is a schematic perspective view of an alternative exemplary embodiment of a needle and container arrangement with different sized containers; 
           [0023]      FIG. 8A  is a schematic view of an apparatus that can be used to perform analytical experimentation with an exemplary embodiment of needle and container arrangement shown in  FIG. 1 ; 
           [0024]      FIG. 8B  is a schematic view of an apparatus that can be used to perform analytical experimentation with an exemplary embodiment of needle and container arrangement shown in  FIG. 1  with its liquids compartment drawer in the open position; 
           [0025]      FIG. 8C  is a schematic view of a needle and container assembly of  FIG. 1  integrated into a liquids compartment of the apparatus used to perform analytical experimentation shown in  FIGS. 8A and 8B ; 
           [0026]      FIG. 8D  is an enlarged schematic view of the needle and container assembly of  FIG. 8C ; and 
           [0027]      FIG. 8E  is a schematic view of the needle and container assembly of  FIG. 8C  showing the cover in an opened position. 
       
    
    
     DESCRIPTION 
       [0028]    Embodiments of the present invention are described below. It is, however, expressly noted that the present invention is not limited just to these disclosed embodiments. Various modifications not specifically detailed are within the scope of this disclosure. All relative descriptions herein such as top, bottom, left, right, up, and down are with reference to the figures, and thus should not be construed in a limiting sense. The present invention can be applied to storing and handling liquids for many types of analytical equipment, such as, for example, flow cytometers and chemical analyzers. Further, the disclosed liquid storage/handling apparatus can be used as part of a system for detecting single molecules by, for example, optical detection of single nucleotides. 
         [0029]    Embodiments of a fluidic apparatus according to the present invention generally streamline the analysis of biochemical assays. Each of the embodiments enables simple and safe loading and unloading of reagent containers, allow for more accurate discharge of reagent volumes, and maximizes the utilization of the liquid volume in each individual container. 
         [0030]    In the embodiment depicted in  FIG. 1 , the liquid storage apparatus  10  includes a plurality of containers  20  filled with liquid reagents being loaded into a frame  40 . The containers  20  are selectively secured to a tray carrier  22  thereby forming a cartridge assembly  24 . Other means for arranging the plurality of containers  20  into a unitary cartridge assembly  24  will be apparent to one skilled in the art. In alternative embodiments, the containers  20  can be loaded into the frame  40  individually or in multiple cartridge assemblies. The containers  20  can be glass or a suitable plastic material such as acrylic, polycarbonate, or polypropylene. In some embodiments, the materials used in each container  20  can be the same or different from the other containers  20  depending on the liquid being stored, such that the liquid is not reactive with the container  20  material. Also, individual liquids may need to be stored in different thermal or atmospheric conditions and therefore thermal expansion characteristics may be an important consideration when selecting the container material. 
         [0031]    Each container  20  includes a top pierceable septum  26  and a bottom pierceable septum  28 . These septa  26 ,  28  can be made from any pliable material that allows penetration by a needle and then seals the outside periphery of the needle to prevent leakage. Examples of such materials are polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene (FEP) and perfluoroalkoxy polymer resin (PFA), which are all generally known by DuPont&#39;s brand name Teflon®. The septa  26 ,  28  can be the same or different depending on the desired application and/or the liquid being stored in each container. The septa  26 ,  28  can be secured to the container  20  in any of a number of ways including, for example, snap on, screw cap, mechanically fastened, heat welding, vibration welding, ultrasonically welding, or bonding with an adhesive. 
         [0032]    The liquid storage apparatus also includes a lower array of needles  60 . Each of the needles of the lower array of needles  60  is disposed in a cavity  42  recessed into the bottom surface  44  of the frame  40 . As the containers  20  of the cartridge assembly  24  are being lowered into the frame  40  in the direction indicated by line A, the bottom pierceable septa  28  are received into the cavities  42 . The cavities  42  can be slightly tapered with the widest part at the bottom surface  44  of the frame  40  to help guide the containers  20  into the cavities  42 . The needles  60  are disposed in the cavities  42  such that the points  62  of the needles  60  are below the bottom surface  44  of the frame  40  to help prevent accidental sticks. The cavities  42  also help ensure proper alignment of the needles  60  in the center of each septum  28  prior to penetration. 
         [0033]    Referring now to  FIGS. 2A and 2B , the containers  20  are shown partially loaded into the frame  40 . Each of the needles in the lower array needles  60  has pierced the bottom pierceable septum  28  of each of the containers  20  and is penetrating into the liquid reagent. Each needle in the lower array of needles  60  has a passage allowing the liquid reagent in the pierced container  20  to flow out of the container  20 . 
         [0034]    The liquid reagents used in certain analytical procedures are very expensive and therefore it is desirable to use as much of the liquid volume as possible to prevent waste. Referring now to  FIGS. 3A and 3B , a Trocar needle for use in the lower array of needles  60  is shown. In this embodiment, the needle  60  has a closed sharpened point  62  and an aperture  64  in the side such. These Trocar needles with a side aperture  64  allow the point  62  of the needle  60  to protrude into the container a sufficient distance to pierce the septum  28 , while also providing the outlet for the liquid near the septum  28 . This allows for a maximum amount of the liquid volume from each container  20  to be utilized. In alternative embodiments, the needles in the lower array of needles  60  can be any type of needle including, for example, a thoracentesis needles, Veress needles, or Huber needles. The needles  60  can be fabricated from stainless steel, titanium or other similarly rigid material in a range of sizes and lengths depending on the requirements of a particular application. 
         [0035]    The liquid storage apparatus also includes an upper array of needles  80 . Each of the needles of the upper array of needles  80  is disposed in a cavity  52  recessed into the bottom surface  54  of a cover  50 . The cover  50  is pivotally attached to the frame  40  with a hinge  56 . The cavities  52  can be slightly tapered with the widest part at the bottom surface  54  of the cover  50  to help guide the containers  20  into the cavities  52 . The needles  80  are disposed in the cavities  52  such that the points  82  of the needles  80  are below the bottom surface  54  of the cover  50 . These cavities  52  are similar to the cavities  42  described above in relation to the frame  40  and perform substantially the same function, such as prevention of accidental sticks and ensuring proper alignment of the needles  80  in the center of each upper septum  26  prior to penetration. 
         [0036]    Referring now to  FIGS. 4A-4C , a deflected tip needle of the upper array of needles  80  is shown. In the deflected tip needle  80 , the sharpened point  82  is slightly bent or offset from the longitudinal axis  84  of the needle  80 . This deflected tip design provides a needle that is non-coring such that as the top pierceable septum  26  is pierced, none of the septum  26  material is removed, which could potentially cause obstructions in the apparatus  10  or microfluidic system. In alternative embodiments, the upper needles  80  can be any type of needle including, for example, a thoracentesis needles, Veress needles, Huber needles, or Trocar needles. The needles  60  can be fabricated from stainless steel, titanium or other similarly rigid material in a range of sizes and lengths depending on the requirements of a particular application. 
         [0037]    After a plurality of individual containers  20  or a cartridge assembly  24  has been loaded in to the frame  40 , the cover  50  can be closed and the needles  80  penetrate the top pierceable septum  26 . The needles in the upper array of needles  80  are relatively short so they all make contact with the top pierceable septa  26  at approximately the same time when the cover is swung shut. As described above, the cavities  54  in the cover  50  are tapered to help align the needles  80  near the center of the top pierceable septa  26  and thus no sophisticated alignment techniques or equipment is necessary. Each needle in the upper array of needles  80  has a passage allowing gas to flow into the container to occupy the space in the in the pierced container  20  created by the liquid reagent flowing out of the container  20 . 
         [0038]    Referring now to  FIG. 5 , a fully loaded liquid storage apparatus  10  is shown. A series of air vents  58  are fluidly coupled to the passages of the needles in the upper array of needles  80 , which allow direct venting of the containers  20  to the atmosphere. As the liquid reagents are withdrawn through the passages in the needles lower array of needles, air can freely enter the containers  20  through the passages in the needles of the upper array of needles  80  to replace the liquid volume as it is removed. Replacing the space occupied by the liquid with air or other gas maintains a consistent operating pressure in the containers  20 , i.e., no vacuum build-up. Providing a consistent operating pressure prevents dispensing errors at selector valves in the liquid handling system. 
         [0039]    The liquid reagents used in some microfluidic volume analyzing equipment have toxic vapors or have an unpleasant odor. In this embodiment, the air vents  58  can be fluidly coupled to a filter (not shown) such as a biological grade filter or to a laboratory ventilation system. In further embodiments, the liquids being stored may be extremely volatile in which case a one way check valve or a series of check valves may be included to allow air to flow into the containers after liquid is withdrawn In yet a further embodiment, certain reagents may be reactive with oxygen and therefore the air vents  58  may be fluidly coupled to an inert gas system to prevent the reagents from degrading. 
         [0040]    Analytical equipment utilizing liquid reagents can be damaged if gasses are allowed to enter the liquid handling system. One way of preventing this damage is to provide liquid level sensors for the entire apparatus or a level sensor at each individual container. Referring now to  FIGS. 6A and 6B , the liquid storage apparatus  10  further includes a liquid level sensor  70 . As shown in  FIG. 6A , the liquid level sensor  70  includes a photo sensor  72  and a light-emitting diode (LED)  74 . The liquid level sensor  70  is positioned on a circuit board  76  below each of the containers  20  along the flow path between the aperture  64  of the lower needle  60  and the outlet  73  to the liquids handling system. The photo sensor  72  is located on the opposite side of the flow path from the LED  74 . This type of liquid level sensor  70  is known as an optical level sensor and can sense the presence or absence of fluid bases on the light transmitted from the LED  74  thought the flow path. Other types of liquid level sensors that can be used with the liquid storage apparatus  10  include, for example, ultrasonic level sensors and capacitance level sensors. 
         [0041]    The liquid level sensors can be configured to shut down the equipment when the liquid in the containers has been fully utilized or to provide notification to the user when the liquid level is either getting low or is completely empty. As shown in  FIG. 6B , a LED  78  is attached to the circuit board  76  next to the container  20 . The LED  78  provides a visual indication to the user when that particular container  20  is empty. The LEDs may also be configured to provide a visual indication of where certain containers  20  should be loaded for particular experimental procedures. 
         [0042]    As shown in  FIGS. 1 ,  2 , and  5 , all of the containers  20  are the same size and shape. Referring now to  FIG. 7 , a liquid storage apparatus  110  is shown with one container  130  larger than the other containers  120 . The tops and bottoms of all of the containers  120 ,  130  are symmetrical having the same size and shape. The top and bottom cavities  142 ,  152  are also the same size and shape such that the containers  120 ,  130  can be loaded in either direction. This universal interface design allows a variety of different container sizes to be used in the liquid storage apparatus  110 . In alternative embodiments, the tops and bottoms of the bottles  120 ,  130  and the top and bottom cavities  142 ,  152  are not all symmetrical (i.e., different sizes and shapes) which can prevent liquid reagents from being loaded in the wrong location. 
         [0043]    As mentioned above, the liquid storage apparatus  110  of the present invention is designed for a wide variety of applications. In certain applications, such as single sequencing of DNA molecules, the liquid reagents can be very expensive. The user can customize the liquid storage apparatus  110  with larger containers for reagents that are used more frequently and smaller containers for those reagents that are used less frequently or in smaller quantities. Additionally, container cartridge assemblies can be designed for specific applications so that the liquid in each container of the assembly is used up at approximately the same time. 
         [0044]    The liquid storage apparatus  10  can be a stand-alone apparatus that can be connected to a variety of lab equipment or it may be integrated into an individual piece of equipment. Referring now to  FIG. 8A-8E , the frame  40  is integrated into a compartment of a single molecule sequencing device  90 . To load the reagents, the user simply slides open the compartment  92  and opens the cover  94 . Individual containers and/or cartridge assemblies are inserted into the appropriate locations. The liquid storage compartment  92  may be subdivided to store liquids at different temperatures. 
         [0045]    The disclosed embodiments are exemplary. The invention is not limited by or only to the disclosed exemplary embodiments. Also, various changes to and combinations of the disclosed exemplary embodiments are possible and within this disclosure.