Abstract:
A device for expression and collection of breast milk includes an actuatable assembly, a breast interface, and a tube. The breast interface is sized to receive a breast and form a fluid tight seal against the breast. The breast interface includes a deformable member disposed within at least a portion of the breast interface. The deformable member deforms in response to actuation of the actuatable assembly and applies vacuum pressure against the breast to express milk. The tube operatively couples the actuatable assembly to the breast interface.

Description:
CROSS-REFERENCE 
     The present application is a non-provisional of, and claims the benefit of U.S. Provisional Patent Application Nos. 61/804,722 filed Mar. 24, 2013; and 61/879,055 filed Sep. 17, 2013; the entire contents of which are incorporate herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to medical devices and methods, and more particularly relates to devices and methods for expression and collection of human breast milk. 
     The exemplary embodiments disclosed herein are preferably directed at expression of breast milk, but one of skill in the art will appreciate that this is not intended to be limiting and that the devices, systems and methods disclosed herein may be used for other treatments requiring application of a differential pressure. 
     Breast pumps are commonly used to collect breast milk in order to allow mothers to continue breastfeeding while apart from their children. Currently, there are two primary types of breast pumps: manually-actuated devices, which are small, but inefficient and tiring to use; and electrically-powered devices, which are efficient, but large and bulky. Therefore, it would be desirable to provide improved breast pumps that are small and highly efficient for expression and collection of breast milk. Additional features such as milk production quantification and communication with mobile devices are further desirable for enhanced user convenience. At least some of these objectives will be satisfied by the devices and methods disclosed below. 
     2. Description of the Background Art 
     The following U.S. patents are related to expression and collection of human breast milk: U.S. Pat. Nos. 6,673,036; 6,749,582; 6,840,918; 6,887,210; 7,875,000; 8,118,772; and 8,216,179. 
     SUMMARY OF THE INVENTION 
     The present invention generally relates to medical devices, systems and methods, and more particularly relates to devices, systems and methods for expression and collection of human breast milk. 
     In a first aspect of the present invention, a device for expression and collection of breast milk comprises an actuatable assembly, a breast interface, and a tube. The breast interface is sized to engage a breast and fluidly seal thereagainst. The breast interface also includes a movable member disposed within at least a portion thereof. The movable member moves in response to actuation of the actuatable assembly and thereby forms a vacuum in the breast interface and applies the vacuum to the breast to express milk therefrom. The tube is operatively coupled to the actuatable assembly and to the breast interface. 
     The actuatable assembly may comprise a piston or a pump, or a pair of pistons or a pair of pumps. Actuation of the actuatable assembly may displace a fluid that is disposed in the tube. 
     The movable member may comprise a flexible membrane. The flexible membrane may have a corrugated region that is configured to expand and collapse. The flexible membrane may deform in response to actuation of the actuatable assembly, and actuation of the actuatable assembly may displace a fluid contained within the tube. The movable member may comprise a deformable member. 
     The breast interface may comprise a resilient and conformable flange for engaging and creating a fluid seal against the breast. 
     A fluid may be disposed in the tube. The fluid may be an incompressible fluid such as water or oil. In other embodiments, a tensile element may be disposed in the tube. The tensile element may comprise a rope, a wire, or a cable. The tensile element may be operatively coupled with the movable member and the actuatable assembly, and may also be concentrically disposed with an axial compressive element that absorbs reactive loads of the tensile element. 
     The device may further comprise a driving mechanism that is operatively coupled with the actuatable assembly, and that is configured to actuate the actuatable assembly. The driving mechanism may include electromechanical device such as a motor. The driving mechanism may be releasably coupled to the actuatable assembly. 
     The breast interface may comprise an exit valve that is configured to control flow of the expressed breast milk into a collection vessel. The exit valve may control the flow by preventing the expressed milk from flowing through the valve when the deformable member is deformed, and allowing the expressed breast milk to flow through the valve when the deformable member is in an undeformed configuration. The exit valve may be integrally formed into the deformable member. 
     The device may further comprise a second actuatable assembly, a second breast interface and a second tube. The second breast interface may be sized to engage a second breast and fluidly seal thereagainst. The second breast interface may have a movable member disposed within at least a portion thereof, and the movable member may deform in response to actuation by either the actuatable assembly or the optional second actuatable assembly and thereby form a vacuum in the second breast interface which is applied to the second breast to express milk therefrom. The second tube may be operatively coupled to the second actuatable assembly and the second breast interface. 
     The device may further comprise a housing having a controller for controlling actuation of the actuatable assembly. The controller may control calculation and display of breast milk production information, and the controller may also control communication with other devices. A power source may be disposed in the housing and the power source provides power to the device for expression and collection of milk. The housing may have a drive mechanism disposed therein for actuating the actuatable assembly. 
     The device may further comprise a collection vessel fluidly coupled with the breast interface. The device may also comprise a sensor adjacent the breast interface, and that is configured to measure an aspect of mil passage therepast. The device may also comprise a display unit for displaying data related to the expression of the milk. A system for expression and collection of breast milk may include the device previously described above. Any of these components may be separate from the other components or they may be disposed in a housing or pendant. 
     In another aspect of the present invention, a device for applying pressure or vacuum to a patient comprises an actuatable assembly, a target tissue interface, and a tube. The target tissue interface is preferably sized to engage a target tissue and fluidly seal thereagainst. The target tissue interface has a deformable member disposed within at least a portion thereof, and the deformable member deforms in response to actuation of the actuatable assembly. This forms a vacuum or pressure in the target tissue interface and applies the vacuum or the pressure to the target tissue. The tube is operatively coupled to the actuatable assembly and the target tissue interface. 
     In yet another aspect of the present invention, a method for expressing and collecting breast milk comprises providing a breast expression and collection device having a breast interface and an actuatable assembly operatively coupled to the breast interface. The breast interface comprises a deformable member. The method also comprises engaging and fluidly sealing a breast with the breast interface and actuating the actuatable assembly. The method also comprises deforming the deformable member in response to actuation of the actuatable assembly thereby creating and applying a vacuum to the breast, and expressing and collecting milk from the breast. 
     The engaging step may comprise engaging a resilient and conformable flange on the breast interface with the breast thereby creating a fluid seal between the breast interface and the breast. 
     Actuating the actuatable assembly may displace a fluid. The fluid may be disposed in a tube that is fluidly coupled with the actuatable assembly and the deformable member. Actuating the actuatable assembly may comprise moving a piston or applying a tension to a tensile element disposed in the tube. The method may further comprise releasing the actuatable assembly from a driving mechanism that is operatively coupled therewith. 
     The method may further comprise repeating the actuating, the deforming and the expressing steps. The method may further comprise quantifying production of the expressed milk and transmitting data related to the expression of breast milk between the breast expression and collection device and a mobile device. The mobile device may be a smart phone, tablet, or computing device. The data may be displayed on a display. The method may also comprise controlling flow of the expressed milk into a collection vessel with a valve fluidly coupled to the breast expression and collection device. Controlling the flow may comprise opening the valve when the deformable member is undeformed, and closing the valve when the deformable member is deformed. Aspects of breast milk may also be sensed with a sensor that may be fluidly or otherwise coupled with the breast interface. 
     The breast expression and collection device may further comprise a second breast interface and a second actuatable assembly operatively coupled to the second breast interface. The second breast interface may comprise a deformable member. The method may further comprise engaging and fluidly sealing a second breast with the second breast interface, and actuating the first or the second actuatable assembly. The method may also comprise deforming the deformable member in the second breast interface in response to actuation of the second actuatable assembly thereby creating and applying a vacuum to the second breast, and expressing and collecting milk from the second breast. Expressing and collecting milk from both breasts may occur simultaneously or it may alternate between both breasts. 
     In still another aspect of the present invention, a method of applying a differential pressure to a patient comprises providing a differential pressure device having an interface and an actuatable assembly operatively coupled to the differential pressure device. The interface comprises a deformable member and the method further comprises engaging and fluidly sealing the interface with a target region on the patient, and actuating the actuatable assembly. The method also comprises deforming the deformable member in response to actuation of the actuatable assembly thereby creating a positive pressure or a vacuum and applying the positive pressure or the vacuum to the target region. Any of the components may be separate from the other components, or they may be diposed in a housing or pendant. 
     Deforming the deformable member may create a positive pressure that is applied to the target region. The target region may comprise the mouth or nose, and applying the positive pressure reduces or eliminates apnea or similar disorders while the patient is sleeping. Deforming the flexible membrane may create a vacuum that is applied to the target region. The target region may comprise a body fluid reservoir, and thus the vacuum causes expression of a body fluid from the reservoir. 
     These and other embodiments are described in further detail in the following description related to the appended drawing figures. 
     INCORPORATION BY REFERENCE 
     All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: 
         FIG. 1  is a perspective view of an exemplary embodiment of a pumping device. 
         FIG. 2  is a perspective view of an exemplary embodiment of a pumping device. 
         FIG. 3  is a cross-section of an exemplary embodiment of a pumping device. 
         FIG. 4  illustrates an exemplary embodiment of an actuatable assembly coupled to a driving mechanism. 
         FIGS. 5A-5B  illustrate an exemplary embodiment of an actuatable assembly coupled to a pendant unit. 
         FIG. 6  is a cross-sectional view of an exemplary embodiment of a breast interface. 
         FIG. 7  is a cross-sectional view of another exemplary embodiment of a breast interface. 
         FIG. 8A  is a cross-sectional view of an exemplary embodiment of an integrated valve in an open position. 
         FIG. 8B  is a cross-sectional view of an exemplary embodiment of an integrated valve in a closed position. 
         FIG. 9A  is a cross-sectional view of an exemplary embodiment of integrated sensors within a breast interface. 
         FIG. 9B  is a cross-sectional view of another exemplary embodiment of integrated sensors within a breast interface. 
         FIG. 10  illustrates an exemplary embodiment of a pendant unit and a mobile device. 
         FIG. 11  illustrates an exemplary embodiment of a pendant unit in communication with a mobile device. 
         FIG. 12  is a cross-sectional view of an exemplary embodiment of a breast interface with a mechanical deformable member. 
         FIG. 13  is a cross-sectional view of an exemplary embodiment of a mechanical driver for a mechanical deformable member. 
         FIG. 14  is a graph illustrating the pump performance of an exemplary embodiment compared to a commercial device. 
         FIG. 15  is a graph illustrating the pumping efficiency of an exemplary embodiment compared to a commercial device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Specific embodiments of the disclosed devices and methods will now be described with reference to the drawings. Nothing in this detailed description is intended to imply that any particular component, feature, or step is essential to the invention. One of skill in the art will appreciate that various features or steps may be substituted or combined with one another. 
     The present invention will be described in relation to the expression and collection of breast milk. However, one of skill in the art will appreciate that this is not intended to be limiting, and the devices and methods disclosed herein may be used in other applications involving the creation and transmission of a pressure differential, such as in the treatment of sleep apnea and/or other remote pressure needs. 
       FIG. 1  illustrates an exemplary embodiment of the present invention. Pumping device  100  includes breast interfaces  105 , a tube  110 , and a controller or pendant unit  115  operatively coupled to breast interfaces  105  through tube  110 . Breast interfaces  105  include resilient and conformable flanges  120 , for engaging and creating a fluid seal against the breasts, and collection vessels  125 . The device may optionally only have a single breast interface. Pendant unit  115  houses the power source and drive mechanism for pumping device  100 , and also contains hardware for various functions, such as controlling pumping device  100 , milk production quantification, and communication with other devices. Tube  110  transmits suitable energy inputs, such as mechanical energy inputs, from pendant unit  115  over a long distance to breast interfaces  105 . Breast interfaces  105  convert the energy inputs into vacuum pressure against the breasts in a highly efficient manner, resulting in the expression of milk into collection vessels  125 . 
     One of skill in the art will appreciate that components and features of this exemplary embodiment can be combined or substituted with components and features of any of the embodiments of the present invention as described below. Similarly, components and features of other embodiments disclosed herein may be substituted or combined with one another. 
     Hydraulic Pumping Device 
     Hydraulic systems can reduce pumping force requirements, and therefore also reduce the size of the pumping device, while maintaining high pumping efficiency. In a preferred embodiment, the pumping device can utilize a hydraulic pumping device to generate a pressure differential against the breast for the expression and collection of milk. 
     Exemplary hydraulic pumping devices are depicted in  FIGS. 2 and 3 .  FIG. 2  illustrates a pumping device  150  with a syringe  155  fluidly coupled to breast interface  160  by tube  165 . Syringe  155  is coupled to tube  165  through a three-way valve  170 . Breast interface  160  contains an exit port  175 . The syringe  155  drives a fluid  180  contained within tube  165  against or away from a flexible member contained within breast interface  160  to create the pressure differential necessary for milk expression from the breast. 
       FIG. 3  illustrates another embodiment of a pumping device  200 . The actuatable assembly  205  includes an assembly housing  210 , a driving element  215 , radial seals  220 , and a shaft  222 . Driving element  215  is operatively coupled to a pendant unit, such as pendant unit  115 , through shaft  222 . The tube  225  contains a fluid  230  and is fluidly coupled to the actuatable assembly  205  and the breast interface  235 . The breast interface  235  consists of an interface housing  240 , a flexible membrane  245 , a reservoir  250 , a sealing element  255 , an expression area  260 , and a drain port  265 . The sealing element  255  includes deformable portion  270 . The drain port  265  is coupled to a collection vessel  275  and includes a flap valve  280 . 
     Actuatable assembly  205  displaces fluid  230  contained within tube  225 , which can be a flexible line. Fluid  230  occupies reservoir  250  within breast interface  235  and is coupled with flexible membrane  245 . Flexible membrane  245  transmits vacuum pressure from fluid  230  to the deformable portion  270  of sealing element  255 . When a breast is engaged into and fluidly sealed with breast interface  235  by sealing element  255 , displacement of the actuatable element  215  produces substantial vacuum pressure against the breast through flexible membrane  245  and deformable portion  270 , resulting in the expression of breast milk into expression area  260 . The expressed milk drains through drain port  265  into collection vessel  275 . Drain port  265  is configured with a flap valve  280  to provide passage of milk while maintaining vacuum pressure in expression area  260 . 
     The fluid for the hydraulic pumping device can be any suitable fluid, such as an incompressible fluid. In many embodiments, the incompressible fluid can be water or oil. Alternatively, the fluid can be any suitable gas, such as air. Suitable incompressible fluids and gases for hydraulic systems are known to those of skill in the art. 
     One of skill in the art will appreciate that components and features of any of the exemplary embodiments of the hydraulic pumping device can be combined or substituted with components and features of any of the embodiments of the present invention as described herein. 
     Actuation Mechanism 
     Many actuation mechanisms known to those of skill in the art can be utilized for the actuatable assembly  205 . Actuatable assembly  205  can be a piston assembly, a pump such as a diaphragm pump, or any other suitable actuation mechanism. The optimal configuration for actuatable assembly  205  can depend on a number of factors, such as: vacuum requirements; size, power, and other needs of the pumping device  200 ; and the properties of the fluid  230 , such as viscosity, biocompatibility, and fluid life requirements. 
       FIG. 3  illustrates an exemplary embodiment in which actuatable assembly  205  is a piston assembly and driving element  215  is a piston. Actuatable assembly  205  includes radial seals  220 , such as O-rings, sealing against assembly housing  210  to prevent undesired egress of fluid  230  and to enable driving of fluid  230 . 
       FIG. 4  illustrates another exemplary embodiment of an actuatable assembly  300  including a pair of pistons  305 . 
     In preferred embodiments, the actuatable assembly includes a driving element powered by a suitable driving mechanism, such as a driving mechanism residing in pendant unit  115 . Many driving mechanisms are known to those of skill in the art. For instance, the driving element, such as driving element  215 , may be actuated electromechanically by a motor, or manually by a suitable user-operated interface, such as a lever. Various drive modalities known to those of skill in the art can be used. In particular, implementation of the exemplary hydraulic pumping devices as described herein enables the use of suitable drive modalities such as direct drive and solenoids, owing to the reduced force requirements of hydraulic systems. 
     Referring now to the exemplary embodiment of  FIG. 4 , the pistons  305  include couplings  310  to a crankshaft  315 . The crankshaft  315  is operatively coupled to a motor  320  through a belt drive  325 . The crankshaft  315  drives the pair of pistons  305  with the same stroke timing in order to apply vacuum pressure against both breasts simultaneously, a feature desirable for increased milk production. Alternatively, the crankshaft  315  can drive the pair of pistons  305  with any suitable stroke timing, such as alternating or offset stroke cycles. 
     The driving mechanism can be powered by any suitable power source, such as a local battery or an AC adaptor. The driving mechanism can be controlled by hardware, such as onboard electronics located within pendant unit  115 . 
       FIG. 5  illustrates an exemplary embodiment of an actuatable assembly  350  that includes releasable coupling  355 . Preferably, actuatable assembly  350  is releasably coupled to a pendant unit  360  and the driving mechanism housed therein. The coupling can be a mechanical coupling or any suitable quick release mechanism known to those of skill in the art. The releasably coupled design allows for flexibility in the configuration and use of the pumping device. For instance, user comfort can be improved through the use of differently sized breast interfaces for compatibility with various breast sizes. Additionally, this feature enables a common pumping device to be used with interchangeable breast interfaces, thus reducing the risk of spreading pathogens. Furthermore, the releasable coupling enables easy replacement of individual parts of the pumping device. 
     One of skill in the art will appreciate that components and features of any of the exemplary embodiments of the actuation mechanism can be combined or substituted with components and features of any of the embodiments of the present invention as described herein. 
     Flexible Membrane 
     In many embodiments such as the embodiment depicted in  FIG. 3 , the flexible membrane  245  is located within breast interface  235  and disposed over at least portion thereof, forming reservoir  250  between the interface housing  240  and the flexible membrane  245 . Preferably, the flexible membrane  245  deforms substantially when subject to the negative pressures created when the fluid  230  is displaced from reservoir  250  by actuatable assembly  205 . The amount of deformation of the flexible membrane  245  can be controlled by many factors, (e.g., wall thickness, durometer, surface area) and can be optimized based on the pumping device (e.g., pump power, vacuum requirements). 
       FIG. 6  illustrates an exemplary flexible membrane  370  with a specified thickness and durometer. 
       FIG. 7  illustrates another embodiment of flexible membrane  375  with corrugated features  380  for increased surface area. 
     Suitable materials for the flexible membrane are known to those of skill in the art. In many embodiments, the flexible membrane can be made of a material designed to expand and contract when subject to pressures from the coupling fluid such as silicone, polyether block amides such as PEBAX, and polychloroprenes such as neoprene. Alternatively, the flexible membrane can be fabricated from a substantially rigid material, such as stainless steel, nitinol, high durometer polymer, or high durometer elastomer. In these embodiments, the rigid material would be designed with stress and/or strain distribution elements to enable the substantial deformation of the flexible membrane without surpassing the yield point of the material. 
       FIGS. 8A and 8B  illustrate preferred embodiments of a breast interface  400  in which an exit valve  405  is integrated into the flexible membrane  410  to control the flow of expressed milk through exit port  415 . The exit valve  405  is opened to allow fluid flow when the flexible membrane  410  is relaxed, as shown in  FIG. 8A , and is closed to prevent fluid flow when the flexible membrane  410  is deformed, as shown in  FIG. 8B . The exit valve  405  enables substantial vacuum pressure to be present in expression area  420  during extraction, while allowing milk to drain during the rest phase of the pump stroke. While many conventional breast pump valves function on pressure differentials alone, the exit valve  405  can preferably be configured to also function on the mechanical movement of flexible membrane  410 . Incorporation of an integrated exit valve  405  with mechanical functionality as described herein can improve the sealing of the breast interface  400  during vacuum creation. Furthermore, the implementation of an exit valve integrally formed within the flexible membrane  410  such as exit valve  405  reduces the number of parts to be cleaned. 
     One of skill in the art will appreciate that components and features of any of the exemplary embodiments of the flexible membrane can be combined or substituted with components and features of any of the embodiments of the present invention as described herein. 
     Milk Collection and Quantification System 
     With reference to  FIG. 3 , expressed milk drains through exit port  265  in flexible membrane  245  into a collection vessel  275 . Collection vessel  275  can be any suitable container, such as a bottle or a bag. In many embodiments, collection vessel  275  is removably coupled to flexible membrane  245 . Collection vessel  275  can be coupled directly or remotely via any suitable device such as extension tubing. 
     In many instances, it can be desirable to track various data related to milk expression and collection, such as the amount of milk production. Currently, the tracking of milk production is commonly accomplished by manual measurements and record-keeping. Exemplary embodiments of the device described herein may provide digital-based means to automatically measure and track milk production for improved convenience, efficiency, and accuracy. 
       FIGS. 9A and 9B  illustrates exemplary embodiments of a breast interface  450  with one or more integrated sensors  455 . Sensors  455  are preferably located in flap valve  460 , but may also be located in exit valve  465 , or any other suitable location for monitoring fluid flow. In a preferred embodiment, at least one sensor  455  is integrated into a valve that is opened by fluid flow and detects the length of time that the valve is opened. The sensor signal can be interrogated to quantify the fluid flow. Suitable sensors are known to those of skill in the art, such as accelerometers, Hall effect sensors, and photodiode/LED sensors. The breast interface can include a single sensor or multiple sensors to quantify milk production. 
       FIG. 10  illustrates an exemplary embodiment of pendant unit  500  in which milk expression data is shown on a display screen  505 . In many embodiments, the pendant unit  500  collects, processes, stores, and displays data related to milk expression. Preferably, the pendant unit  500  can transmit the data to a second device, such as a mobile phone  510 . 
       FIG. 11  illustrates data transmission  515  between pendant unit  500  and a mobile phone  510 . Suitable methods for communication and data transmission between devices are known to those of skill in the art, such as Bluetooth or near field communication. 
     In exemplary embodiments, the pendant unit  500  communicates with a mobile phone  510  to transmit milk expression data, such as expression volume, duration, and date. The mobile phone  510  includes a mobile application to collect and aggregate the expression data and display it in an interactive format. Preferably, the mobile application includes additional features that allow the user to overlay information such as lifestyle choices, diet, and strategies for increasing milk production, in order to facilitate the comparison of such information with milk production statistics. Additionally, the pendant unit  500  can send information about the times of pump usage to the mobile phone  510  so that the mobile application can identify when pumping has occurred and set reminders at desired pumping times. Such reminders can help avoid missed pumping sessions, and thus reduce the incidence of associated complications such as mastitis. 
     One of skill in the art will appreciate that components and features of any of the exemplary embodiments of the milk collection and quantification system can be combined or substituted with components and features of any of the embodiments of the present invention as described herein. 
     Mechanical Pumping Device 
       FIG. 12  illustrates an alternative embodiment of a breast interface  600  in which a mechanical deformable member  605  can be used in place of a flexible membrane. The mechanical deformable member  605  can be constructed from similar techniques as those used for the flexible membrane as described herein. The mechanical deformable member  605  is coupled to a tensile element  610 . In some instances, tensile element  610  is disposed within an axial load absorbing member  615 . The axial load absorbing member  615  is disposed within tube  620 . Preferably, tensile element  610  is concentrically disposed within axial load absorbing member  615  and axial load absorbing member  615  is concentrically disposed within tube  620 . Alternative arrangements of tensile element  610 , axial load absorbing member  615 , and tube  620  can also be used. 
       FIG. 13  illustrates the tensile element  610  coupled to driving element  625  of an actuatable assembly  630  within an assembly housing  635 . Driving element  625  is operatively coupled to a driving mechanism, such as a driving mechanism housed within a pendant unit, through shaft  640 . Axial load absorbing member  615  within tube  620  is fixedly coupled to the assembly housing  635 . Displacement of the driving element  625  transmits tensile force through tensile element  610  to the mechanical deforming member  605  to create vacuum pressure against the breast. 
     The tensile element  610  can be any suitable device, such as a wire, coil, or rope, and can be made from any suitable material, such as metals, polymers, or elastomers. Axial load absorbing member  615  can be made from any suitable axially stiff materials, such as metals or polymers, and can be configured into any suitable axially stiff geometry, such as a tube or coil. 
     One of skill in the art will appreciate that components and features of any of the exemplary embodiments of the mechanical pumping device can be combined or substituted with components and features of any of the embodiments of the present invention as described herein. 
     Experimental Data 
       FIGS. 14 and 15  illustrate experimental pumping data obtained from a commercial breast pump device and an exemplary embodiment of the present invention. The exemplary embodiment utilized an incompressible fluid for pumping and had a maximum hydraulic fluid volume of 4 cc, while the commercial device utilized air for pumping and had a maximum volume of 114 cc. 
       FIG. 14  illustrates a graph of the pump performance as quantified by vacuum pressure generated per run. For the exemplary embodiment, pressure measurements were taken for 1 cc, 2 cc, 3 cc, and 4 cc of fluid volume displaced by the pump, with the run number corresponding to the volume in cc. For the commercial device, measurements were taken with the pump set to one of seven equally incremented positions along the vacuum adjustment gauge representing 46 cc, 57 cc, 68 cc, 80 cc, 91 cc, 103 cc, and 114 cc of fluid volume displaced by the pump, respectively, with the run number corresponding to the position number. Curve  700  corresponds to the exemplary embodiment and curve  705  corresponds to the commercial device. The exemplary embodiment generated higher levels of vacuum pressure per displacement volume compared to the commercial device, with maximum vacuum pressures of −240.5 mmHg and −177.9 mmHg, respectively. 
       FIG. 15  illustrates a graph of the pump efficiency as measured by the maximum vacuum pressure per maximum volume of fluid displaced, with bar  710  corresponding to the exemplary embodiment and bar  715  corresponding to the commercial device. The exemplary embodiment demonstrated a 42-fold increase in pumping efficiency compared to the commercial device, with efficiencies of −71.1 mmHg/cc and −1.7 mmHg/cc, respectively. 
     While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.