Abstract:
Disclosed is a small volume, liquid dispenser having particular application in the analytical fields. The liquid dispensers can be quickly and reliably filled to a predetermined volume without monitoring liquid flows or volumes or filling times. Various versions of the dispenser and systems utilizing one or more of the dispensers are disclosed.

Description:
BACKGROUND 
     The present exemplary embodiment relates to liquid dispensers. It finds particular application in conjunction with small volume, analytical liquid dispensers, and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications. 
     Three types of bio-ejection systems dominate the market today. 
     The first type consists of a large reservoir of liquid, connected to an ejection system via tubing. For example, in certain systems, one or more tubes are in communication with a very fine tube. Pressure pulses behind the liquid cause droplet ejection off the end of the small flow volume tube. In this system, the reservoir filling volume may not be critical, and once the tubing is charged or primed, there is little need for anything other than consistent ejection. 
     A second type of system is based upon contact printing. In this arrangement, an array of needles is dipped into a supply of liquid. A droplet of liquid wets each needle or pin as the array is withdrawn from the supply. The residual drop is then contacted to the substrate where the drop wicks onto the surface. 
     A third system aspirates and ejects. In this type of system, the liquid is drawn into the ejection system from a liquid supply. Once in the ejection mechanism, all or portions of the drawn volume may be ejected. 
     All of these systems are fixed systems and hardware intensive. Furthermore, the systems are relatively expensive. 
     Traditionally, filling single ejectors has been performed manually. In order to simplify the filling, it would be convenient to fill an ejector without monitoring quantity, time, or other parameters. If the filling stopped when the internal reservoirs filled to their maximum, without any close monitoring, that would render the filling system much easier to build and manage. Accordingly, a need exists for such a filling configuration. 
     BRIEF DESCRIPTION 
     In accordance with one aspect of the present exemplary embodiment, a liquid dispenser is provided which is adapted to allow filling with liquid to a predetermined volume, without intensive monitoring requirements. The dispenser comprises a lid defining an upper surface, an oppositely directed lower surface, and a fill aperture extending between the upper surface and the lower surface. The dispenser also comprises a base component defining a bottom face, and an oppositely directed inner face. The base component further defines a channel extending therethrough and provides fluid communication between the inner face and the bottom face. The dispenser further comprises a liquid reservoir disposed between the lid and the base. The reservoir defines a hollow region and a passage providing communication to the hollow region wherein the passage is in fluid communication with the channel of the base component. The dispenser further comprises a liquid stop device disposed between the fill aperture of the lid and the hollow region of the liquid reservoir. 
     In accordance with another aspect of the present exemplary embodiment, a liquid dispenser adapted to readily accommodate filling to a selected predetermined volume is provided. The dispenser comprises a lid defining a first fill aperture and a second fill aperture. The dispenser also comprises a base including an apertured region, a liquid port, and a channel providing flow communication between the apetured region and the liquid port. The dispenser further comprises a liquid reservoir disposed between the lid and the base and defining a first interior hollow region and a second hollow interior region. Both the first and second regions are accessible from a passageway defined in a wall of the reservoir. The dispenser also comprises a first liquid stop device disposed between the first fill aperture and the first interior hollow region defined in the liquid reservoir. The dispenser further comprises a second liquid stop device disposed between the second fill aperture and the second interior hollow region defined in the liquid reservoir. 
     In accordance with yet another aspect of the present exemplary embodiment, a system is provided for readily filling at least two liquid dispensers. The system comprises a distribution header providing access to a vacuum source or pressure differential. The header includes at least two access members. The system also comprises at least two liquid dispensers in which each dispenser is adapted to be placed in communication with a corresponding access member and thereby in communication to the vacuum source. Each dispenser includes (i) a lid defining a fill aperture for communication with the vacuum source, (ii) an apertured base, (iii) a liquid reservoir disposed between the lid and the base, and (iv) a liquid stop device disposed in the flow path between a corresponding access member and the liquid reservoir. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of an exemplary embodiment dispenser. 
         FIG. 2  is a schematic side view of another exemplary embodiment dispenser. 
         FIG. 3  is a schematic of an exemplary embodiment system including multiple dispensers that can be simultaneously filled. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an exemplary embodiment bio-ejector liquid dispenser  100 . The dispenser  100  comprises a cap  10 , a reservoir  20 , an optional piezo electric element  30  and substrate  40 , and a base component  50 . The reservoir  20 , piezo element  30 , and substrate  40  are disposed between the cap  10  and the base component  50 . The cap  10  defines a centrally located aperture  12  along an outermost upper face  16  and a secondary aperture  14  defined along the perimeter of the cap  10 . The cap  10  further defines a lower surface (not shown) oppositely directed from the upper face  16 . The apertures  14  and  12  extend between the upper face  16  and the lower face. The reservoir  20  is generally cylindrical and defines an interior hollow region extending between an outerwall  27 , an upwardly extending post  24 , and a floor  25  extending between the wall  27  and the post  24 . An aperture  21  is defined along the floor  25  of the reservoir  20 . The post  24  defines an aperture  26  or a receiving region generally extending across the height of the post  24 . Disposed between the aperture  14  defined in the cap  10  and the reservoir  20 , is a liquid stop component  22 , described in greater detail below. The piezo component  30  is situated between the reservoir  20  and the substrate  40 . As explained in greater detail herein, the piezo component  30  is affixed or otherwise retained on the substrate  40 . The piezo component  30  and the substrate  40  are optional and described below. The substrate  40  and the cap  10  are generally shaped to match or at least accommodate the cross-sectional shape of the reservoir  20 . For cylindrically shaped reservoirs  20 , the cap  10  and substrate  40  are circular shaped. The substrate  40  also defines an aperture  42  defined along its perimeter. Aperture  42  is described in greater detail herein. The base component  50  defines an inner face  51 , an oppositely directed bottom face (not shown), a recessed liquid receiving port  52 , an outwardly extending tip  58  with an aperture or ejection hole  59  accessible at the distal end of the tip  58 , a fluidway  56  extending within the tip  58 , and a channel  54  extending between the port  52  and the fluidway  56 . It will be appreciated that the base component  50  does not require the outwardly projecting tip  58 . In an alternate version, the base component  50  could be devoid of such a tip  58 . The fluidway  56  could extend between the inner face  51  and an oppositely directed outer face (not shown). 
     The piezo component  30  and its substrate  40  can optionally be used or incorporated in the dispenser to provide an electrical signal upon application of a predetermined stress to the substrate. Such stress may indicate filling of the dispenser or engagement with a holder, for example with the aperture  26  in reservoir  20  in  FIG. 1 . 
     Referring further to  FIG. 1 , the reservoir  20  is filled by drawing liquid up through the tip  58 . A vacuum source or source for inducing a pressure differential relative to the liquid source, is placed in communication with the aperture  14 . Evacuating air exits from the dispenser through the liquid stop device  22  and out of the cap  10 . Once the liquid level in the reservoir  20  contacts the liquid stop device  22 , filling ceases. When the liquid front hits the stop device  22 , the vacuum continues to pull on the liquid, degassing it to some degree. The dispenser is then full, and ready for use. A pressure or vacuum may be applied to the fluid in the dispenser, through the stop device, during ejection. 
     The exemplary embodiment dispenser is configured such that it has a face, such as cap  10  in  FIG. 1  which connects to a holder and vacuum source. That is, the dispenser can be configured to engage with and be affixed to, a holder that extends through the aperture  12  in the cap  10  and which is received in the aperture  26  of the reservoir  20 . The exemplary embodiment dispenser however is not limited to this particular configuration and includes other configurations for engagement with a holder. More specifically, aperture  12  serves to allow a pogo pin electrical connection to the piezo element. However, it will be understood that the aperture can serve many different functions depending upon the particular application. 
     The opposite end of the exemplary embodiment dispenser  100  includes an aperture, such as tip  58  in  FIG. 1 , which may be dipped, immersed, or otherwise placed in communication with a liquid supply. The apertured tip  58  is immersed or at least contacted with the liquid supply. Upon application of a vacuum or pressure differential such as at aperture  14 , liquid is displaced into the tip  58  and into the internal volume of the dispenser. 
     The internal volume of the exemplary embodiment dispenser is designed such that is has minimal unswept volumes. A liquid front coming in from the liquid supply, such as from the distal end of the tip  58 , sweeps all of the air out as the liquid front progresses toward the vacuum source. Referring to  FIG. 1 , the dispenser  100  includes a smooth fluidway  56  which transitions into an arcuate channel  54 . The channel  54  provides fluid communication between the fluidway  56  and the port  52 . The dispenser  100  and its components are assembled such that the port  52  is positioned adjacent or proximate to the aperture  42  in the substrate  40 . The aperture  42  is aligned with the aperture  21  of the reservoir  20 . The liquid stop device  22  is positioned between the reservoir  20  and the aperture  14  in the cap  10 . 
     The air in the dispenser exits through the stop device such as device  22  in  FIG. 1 . The stop device is generally incorporated as part of the dispenser manufacturing process. However, the exemplary embodiment includes configurations in which the stop device is incorporated into a dispenser after assembly of the dispenser. 
       FIG. 2  schematically illustrates another exemplary embodiment dispenser  200  adapted for selective volume filling. The dispenser  200  comprises a cap  110 , a base  160 , and a reservoir  120  providing an interior hollow, liquid-holding region denoted as sub regions C and D. The dispenser  200  enables filling to a volume corresponding to region C, or to a volume corresponding to the sum of the volumes of regions C and D. The lid  110  defines a first aperture  114  and a second aperture  116  both extending through the thickness of the lid  110 . The lid defines an outer face  111  and an oppositely directed inner face  112 . The lid also defines a recessed region along the face  112  that in turn defines the region D. Disposed in flow communication with apertures  114  and  116  in the lid  110  are liquid stop devices  122  and  124 , respectively. As will be appreciated, the liquid stop devices  122  and  124  can be disposed along the face  112  of the lid  110  such that they are flush with that face, as with device  124 , or project outward from that face, as with device  122 . The reservoir  120  defines an internal volume for receiving and storing a liquid  180 . The base  160  defines at least one fluid passageway (not shown) which provides for fluid communication between the internal volume of the reservoir, i.e. regions C and D, and a bottom face  162  of the base  160 . 
     The dispenser  200  is filled by contacting the surface  162  of the base  160  with a liquid, or immersing, either wholly or partially, the dispenser  200  or more specifically the base  160 , in liquid. A first vacuum source  190  is applied over the aperture  114 . The vacuum source  190  can be in the form of a tube  192  having a sealing component  194  on its distal end through which vacuum A is applied. A second vacuum source  195  is provided in the form of tube  197  having sealing component  199  through which vacuum B is applied. In the event it is desired to fill the dispenser  200  to volume C, or rather to a particular level such as level E, vacuum A is applied to the aperture  114  thereby drawing liquid  180  into the region C of the reservoir  120 . Upon the level of liquid  180  entirely contacting or covering the liquid stop member  122 , filling of the dispenser ceases. In the event it is desired to fill the reservoir to a greater volume, such as by an increase corresponding to the volume of region D, vacuum B is applied to the aperture  116  thereby drawing liquid  180  into the region D of the reservoir  120 . Upon the level of liquid  180  entirely contacting or covering the liquid stop member  124 , filling of the dispenser  200  ceases. 
     All of the components of the exemplary embodiment dispensers can be formed from nearly any suitable material. Representative examples for forming the cap, reservoir, substrate, and tip component include plastic and metal. Plastic is generally preferred due to its low cost and ability to be molded. The optional piezo component is formed from materials known in the art. The substrate on which is disposed or affixed the piezo component, is preferably formed from stainless steel or other suitable metal. 
     The liquid stop device, such as item  22  in  FIG. 1  or items  122  and  124  in  FIG. 2 , is preferably formed from a thin layer of a gas permeable material such as Gore-Tex®, available from W. C. Gore &amp; Associates. The Gore-Tex® membrane is a composite of two unique materials having mechanical and chemical stability. 
     One of the two components in Gore-Tex® is pure expanded polytetrafluoroethylene PTFE which is a hydrophobic or water-hating material. Integrated in the PTFE structure is an oleophobic, or oil-hating substance which allows moisture vapor to pass through, but is a physical barrier that prevents the penetration of contaminating substances such as oils, cosmetics etc. which could affect the waterproof performance. Representative grades of Gore-Tex which are particularly suitable for the exemplary embodiment dispensers include, but are not limited to Gore-Tex Membrane. The exemplary embodiment dispenser includes the use of other materials for the liquid stop device besides Gore-Tex®. Representative examples of alternate materials besides Gore-Tex which are suitable for the exemplary embodiment dispensers include, but are not limited to porous nylon, porous polymers, or mesh fabrics which are treated such that their surface tension is low and causes the liquid to be repelled rather than absorbed. 
     In certain alternate embodiments or variations, it is contemplated to avoid the use a separate liquid stop device, such as device  22  in  FIG. 1 , and instead utilize a relatively small aperture defined in the cap or in a substrate incorporated in the dispenser so as to replace the device  22 . The aperture is sized so as to prevent or preclude the passage of liquid, yet allow gas to flow therethrough. Although the diameter of such a small aperture will vary depending upon the liquid and solid combination, and the degree of pressure differential between the liquid and vacuum, it is contemplated that the aperture will have a diameter of from about 10 to about 30 micron, more preferably from about 0.1 micron to about 3 micron, and most preferably from about 0.1 micron to about 1 micron. The use of multiple apertures is also contemplated, and may be required to provide sufficient evacuated air flow. 
     The exemplary embodiment dispensers are different from currently known devices in that they can be in the form of a single dispenser, which contains all of its liquid. The dispenser is filled prior to many ejection runs. A plurality of dispensers could be used in parallel to create complex arrays of liquids. Once the ejection is done, the dispenser could be stored, refilled, cleaned, or disposed of. The dispenser is designed to be inexpensive. Liquid stop  22  could be replaced for reuse should it become damaged. 
       FIG. 3  schematically illustrates an exemplary embodiment system  300  for simultaneously filing a plurality of dispensers  210 ,  220 , and  230 . A distribution header providing access to a vacuum source  240  is utilized having a corresponding number of stand-offs or access members, such as members  212 ,  222 , and  232 . A multi-well liquid retainer  205  defining a plurality of wells containing liquids X, Y, and Z is provided. The system  300  having dispensers  210 ,  220 , and  230  is placed in fluid communication with corresponding wells of the retainer  205 . A source of vacuum  240  is applied to each of the dispensers, each dispenser being in fluid communication with a respective well, to thereby draw a predetermined amount of the liquid in a particular well into the corresponding dispenser. For example, upon application of the vacuum from source  240 , liquid X is drawn into dispenser  210 , liquid Y is drawn into dispenser  220 , and liquid Z is drawn into dispenser  230 . Filling of the dispensers can occur concurrently and until a predetermined reservoir volume in each dispenser is filled. 
     Instead of utilizing one or more liquid stop devices as described herein, or very fine apertures that allow passage of air but preclude that of liquid, the exemplary embodiment dispensers could utilize other equivalent components to restrict or block the flow of liquid. Examples include, but are not limited to one or more necked down channels, channels with flow restrictions, or channels with appropriate nonwetting properties. Moving check valve mechanisms could be utilized. Ball float valves, or flap valves, for example may be used. A floating ball in the reservoir, which seals against a vacuum hole once liquid floats it into position, could be employed. These mechanisms would be desirable for ejectors other than biofluid ejectors. 
     There exist numerous advantages with regard to the exemplary embodiment dispensers described herein. The exemplary embodiment dispenser simplifies the filling steps. The dispenser needs only to be filled simply and robustly in order to succeed. The dispenser is easy to incorporate in existing systems, and inexpensive. The dispenser, with liquid stop, allows pressure regulation of the volume inside the ejector during operation, without allowing liquid to be inadvertently drawn into the regulation system. 
     Although the exemplary embodiment ejectors and ejector systems described herein utilize a piezo ejection method, the exemplary embodiment includes other types and configurations such as, but not limited to, a thermal ink jet type of ejector, an acoustic ejector, a pulsed capillary tube ejector, and a pulsed solenoid style ejector. 
     Although the exemplary embodiment dispenser has been described in terms of being assembled from multiple components, the dispenser can be formed as a unitary one-piece item. In addition, one or more features of any of the dispensers described herein can be interchanged or used in conjunction with one or more features of any other dispenser or system described herein. 
     While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications, variations, improvements, and substantial equivalents.