Abstract:
An apparatus for delivering fluid from a fluid container comprises a housing to which a fluid container is attachable, a slider movably disposed in the housing and a resilient having a first end connected to the housing and a second end connected to the slider. Upon receiving an external force, the slider moves relative to the housing from a first position toward a second position to deform the resilient member from an original state to a deformed state, and upon release of the external force, the resilient member is allowed to resume to the original state to move the slider toward the first position to urge the slider against the fluid container to deliver fluid from the fluid container under a constant fluid flow rate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This claims priority to Singapore Patent Application Serial No. 10201604323Y filed May 30, 2016, the disclosure of which is hereby incorporated by reference as if set forth in its entirety herein. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to an apparatus and system for delivering fluid from a fluid container. In particular, it relates to an apparatus and system for infusion and injection of fluid medical substance. 
       BACKGROUND 
       [0003]    The use of ambulatory, mechanically driven infusion devices or pumps have gain wide acceptance due to its ease of use, safe and effective means of drug delivery in both hospital and non-hospital based settings. The salient benefits are derived from the absence of programming or infusion settings, unlike electronic pumps which can lead to serious adverse events arising from human errors. 
         [0004]    The general principle of such mechanical pumps is based on a force or pressure action on a body of fluid within an enclosed container or receptacle such that the fluid is pushed out through a flow restrictor connected to the container. For any given pressure acting on the fluid, the flow rate achieved is determined by the internal diameter of the lumen of the restrictor based on Bernoulli&#39;s and/or Hagen principle. 
         [0005]    Albeit the safety element imbued in mechanical pumps, there are limitations that relates to flow accuracy and costs, particularly when the pump is intended for single use only. The flow rate accuracy which is typically designed to meet prevalent international standards of +/−15% limits the device to its use with only drugs that allow greater tolerant ranges. There are also other issues pertaining to storage and operational use, for example if the device is constructed with elastomeric membranes as reservoir, the pressure generated would be affected by the time duration and conditions of storage. 
       SUMMARY 
       [0006]    In one embodiment, a reusable spring driven apparatus that enables fluid delivery including the infusion of medication at an accurate and uniform flow rate is disclosed. 
         [0007]    The disclosed embodiments can employ the use of a constant force tape spring to produce a significantly uniform force that acts on a body of fluid filled in a generally tubular container such as a syringe. In one embodiment, a syringe has a rigid cylindrical barrel that is open on the back end and a plunger or a piston like contraption is axially movable within the container through the back end. The front end of the barrel has a tip or nozzle that lends itself to fluid communication with the outlet of a tube along which a flow restriction element such as a valve or a clip is provided, either by its internal diameter or a purposely designed capillary in its path. When the plunger, which includes a fluid sealing feature, is pushed towards the nozzle, the fluid contents e.g. liquid medicine inside the barrel would be discharged via the nozzle. 
         [0008]    The apparatus that drives the plunger includes a resilient member, e.g. a constant force spring of a thin, flat tape shape connected to a slider which is movably disposed in a housing. The spring has a first end protruding out of the slider and connected to the housing, and a second end connected to the slider. When no external force is applied, the spring is coiled about the second end, with a major portion of the spring wounded and received in the slider. When an external force is applied to the slider, as the first end of the spring is connected to the housing, the slider is moved relative the housing in a direction away from the first end, to create the required linear displacement that uncoils the spring out of the slider to store a potential energy in the spring. A syringe can be attached to the housing, with the plunger abutting against the slider. The slider counteracts against the plunger to exert a driving force to the plunger. When the valve or clip connected to the nozzle of the syringe is opened, the potential energy stored in the spring is allowed to release, such that the driving force presses against the plunger in pushing the fluid out of the syringe, to deliver the fluid to a user e.g. a patient to whom the syringe is connected. 
         [0009]    In one embodiment, an apparatus is configured to support syringes filled with any volume of liquid medicine up to the maximum capacity that is specified for a particular model of a syringe. This feature provides less limitations to the selection and use of the syringes as the volume of medication needs no longer be restricted to any specified volume of liquid medicine filled in the syringe. 
         [0010]    In one embodiment, the housing includes a hollow mandrel in which the slider is movably disposed, and a sleeve telescopically coupled to an external side surface of the mandrel, through helical thread grooves formed on the inner surface of the sleeve and corresponding helical thread ridges formed on the external surface of the hollow mandrel. When an external force is applied against the slider, by e.g. the engagement of the plunger of a syringe attached to the sleeve, rotating the hollow mandrel relative to the sleeve will displace the slider and the coiled section of the spring away from the first end of the spring, relative to the hollow mandrel. The displacement maybe equivalent to the length the plunger needed to travel with respect to the syringe barrel, in order to push the fluid out from the syringe. 
         [0011]    The slider maybe pushed away from the first end with a distance longer than the plunger travel distance, to reserve in the spring a residual or pre-stressed force for acting on the plunger via the slider. This pre-stressed force is advantageous to provide a relatively more constant force against the plunger until the volume of the fluid filled in the syringe is completely dispensed, to ensure the liquid medicine delivery in a relatively more constant flow rate. 
         [0012]    In addition to the practical benefits described above, embodiments described herein provide a technological advantage whereby moving a coiled section of the spring is relatively easier to achieve and control, for example via an axle mechanism coupled to the slider that moves along a track guide in the hollow mandrel. 
         [0013]    Another additional advantage is the use of a coupling element on the slider for engaging a syringe plunger in creating a pre-stress force in the spring. The aforesaid coupling element enables the use of the approximate constant range of the force profile in driving the plunger of a syringe, for fluid delivery under a relatively more constant flow rate. The result of achieving a relatively more constant force profile throughout the displaced distance of the plunger enables the syringe to be filled with varying volume of fluid without affecting the intended flow rate of fluid delivery. 
         [0014]    A further aspect of the present disclosure is the use of hollow mandrel and telescopic sleeve to support syringes filled with different volume of liquid medicine. In one embodiment, the slider is movably disposed in the hollow mandrel and the syringe is attached to the sleeve. When the hollow mandrel is rotated relative to the sleeve by means of the screw threads engagement, surface overlaps between the sleeve and the hollow mandrel can be progressively adjusted and set at any position relative to each other to adapt to syringes of plungers extended in different lengths. The uncoiling of the coiled section of the spring is due to the action of the plunger and coupling on the slider when the hollow mandrel and the sleeve overlaps incrementally. The combined effect is to displace the coiled section of the spring and the slider away from the first end of the spring which is affixed to the hollow mandrel, causing uncoiling and extension of the spring and storing potential energy in the spring. 
         [0015]    In another embodiment, uncoiling of the spring can also be achieved by directly sliding the hollow mandrel into the sleeve element to cause more overlapping surface areas between the sleeve and the hollow mandrel, although the force required in this method is appreciably higher compared to a rotational movement of the sleeve relative to the housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1A  is a perspective view of an apparatus for delivering fluid according to one embodiment; 
           [0017]      FIG. 1B  is a perspective view showing the apparatus of  FIG. 1A  to which a fluid container is attached for fluid delivery; 
           [0018]      FIG. 2  is an exploded perspective view of  FIG. 1A ; 
           [0019]      FIG. 3  is a partial enlarged view of portion  3  of  FIG. 2 ; 
           [0020]      FIG. 4A  is a cross sectional perspective view of  FIG. 1A  showing the slider at the first position adjacent to the entrance of the sleeve; 
           [0021]      FIG. 4B  is a perspective view showing the position of the slider of the apparatus shown in  FIG. 4A ; 
           [0022]      FIG. 5  is a cross sectional perspective view of  FIG. 1A  showing the slider at the second position; 
           [0023]      FIG. 6  is a cross sectional perspective view of the apparatus of  FIG. 1A  to which a filled fluid container is to be attached; 
           [0024]      FIGS. 7(A), 7(B), 7(C) and 7(D)  are cross sectional perspective views showing a method of attaching a fluid container to the apparatus of  FIG. 1 ; 
           [0025]      FIG. 8A  is a cross sectional perspective view of the apparatus of  FIG. 1A  to which a fluid container is attached and ready for delivering fluid from the fluid container; 
           [0026]      FIG. 8B  is a perspective view showing the slider of the apparatus shown in  FIG. 8A ; 
           [0027]      FIG. 9  is a cross sectional perspective view of the apparatus of  FIG. 1A  to which a fluid container is attached, after completion of the fluid delivery; 
           [0028]      FIG. 10  is a perspective view of the slider and spring assembly of the apparatus shown in  FIG. 2 ; 
           [0029]      FIG. 11  is a side view of  FIG. 10 ; 
           [0030]      FIG. 12  is a diagram showing a system for fluid delivery according to an embodiment; 
           [0031]      FIG. 13  is a chart showing a flow profile of an apparatus of  FIG. 1A  used to deliver fluid from a fluid container attached to the apparatus; 
           [0032]      FIG. 14  is a diagram showing mobile connectivity of an apparatus of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Examples of embodiments will be shown to provide an understanding of the principles of the design features, its function, manufacture, use of the device and methods disclosed. The embodiments shown are intended to be exemplary and non-limiting. The features described in the embodiment may be combined with variants or modifications of other embodiments to achieve the goals of a device with the features and novelties described. Such variants or modifications are intended to be within the scope of the present disclosure. 
         [0034]    By way of a non-limiting example,  FIGS. 1A, 1B, 2 and 3  illustrate an apparatus  10  for delivering fluid from a fluid container according to one embodiment. Apparatus  10  has a housing  13 , a slider  210  movably disposed in housing  13  and a resilient member  215  connected between the housing  13  and the slider  210 . In the present embodiment, housing  13  includes a hollow mandrel  101  and a sleeve  301  movably coupled to hollow mandrel  101 , and slider  210  is movably disposed in the hollow mandrel  101 . Sleeve  301  has an entrance  307  formed at one end. Entrance  307  includes a rim  308  extending radially and inwardly from side wall  306  of sleeve  301 , and an opening  309  surrounded by rim  308 . 
         [0035]    The resilient member is a thin, flat shaped tape spring  215  made of elastically deformable material, e.g. metal, and coiled to form a reel as shown in  FIGS. 2, 3 ,  4 A and  4 B. Spring  215  has a first end  217  at the outer end of the reel, and a second end  212  at the inner end of the reel. Spring  215  is wound around an axle  216  at the second end  212 , and the axle  216  is attached to the slider  210 . A hollow core  218  may be used to support spring  215  and coupled to axle  216  via a bearing  219 . The first end  217  extends out of the slider  210  and is connected to the housing  13  i.e. in the present embodiment, the first end  217  is connected to the hollow mandrel  101 . 
         [0036]    The spring  215  is at the original, un-deformed state when coiled and with a major portion of the spring  215  received in the slider  210 , as shown in  FIGS. 4A and 4B . Upon receiving an external force F 1 , the slider  210  moves relative to the hollow mandrel  101  away from the entrance  307 , causing the spring  215  to be pulled out and uncoil from the slider  210  and stores a potential energy in the spring  215 , as shown in  FIG. 5 . The potential energy will generate a driving force required to push fluid out of a fluid container, such as a syringe, attached to the apparatus  10 . The displacement of the slider  210  in the hollow mandrel  101  is constrained by guide channels  203  and  204  that could be made from separately formed parts installed within the inner walls of the hollow mandrel  101 , or the guide channels  203  and  204  could be integrated to the hollow mandrel  101  itself. The guide channels  203 ,  204  assist in aligning the direction of the displacement of the slider  210  to be in a generally parallel direction as the axis of the plunger movement within the fluid container. The choice of the number of springs or its dimensions i.e. width, outer diameter, thickness and spring material determines the force that is desired. 
         [0037]    The axle  216  may be configured to be free to rotate relative to the slider  210 , to ease the spring  215  coiling and uncoiling about the axle  216 . Alternatively, axle  216  may be fixed to slider  210  while the second end  212  of the spring  215  is rotatably attached around the axle  216  to maintain connection between the slider  210  and the spring  215  during coiling and uncoiling of the spring  215  around the axle  216 . 
         [0038]    In this embodiment, the constraints in the volume space of the hollow mandrel  101  corresponds to the use of a single spring, in order to provide a desired force for expelling fluid from a fluid container attached to the apparatus  10 . In other embodiments, the spring set could be a single spring or multiple springs arranged in appropriate configurations to provide desired force. By way of example, multiple springs could be arranged within a common axis or with their axes along the lateral direction in which they are displaced when the apparatus is in use. 
         [0039]    The mandrel  101  shown in  FIGS. 4A and 4B  is at fully extended position out of the sleeve  301 . The slider  210  is disposed in mandrel  101  and movable relative to mandrel  101  long the channels  203  and  204 . When the spring  215  is coiled, a majority portion of spring  215  is wound around axle  216  and received in the slider  210 , while the slider  210  is located generally at the first position, adjacent to the entrance/open end  307 / 309  of the sleeve  301  as shown in  FIG. 4A . When an external force F 1  is applied to slider  210  along direction  12  i.e. away from entrance  307 , the slider  210  will be pushed away from entrance  307 , as shown in  FIG. 5 . 
         [0040]    The sleeve  301  has helical thread grooves  305  formed on its inner sidewall. Screw threads  105  of corresponding dimension and pitch are formed on the outer surface of the hollow mandrel  101 . Engagement of the thread grooves  305  and screw threads  105  will allow rotation of the hollow mandrel  101  relative to the telescopic sleeve  301  and by such rotation, the hollow mandrel  101  will be moved relative to the sleeve  301  along axial direction  14 . The screw threads  105  could be a single loop or multiple loops around the outer circumference of the hollow mandrel  101 . 
         [0041]    As shown in  FIGS. 6 and 7 (A) to  7 (D), in use, a syringe  40  is firstly filled with a desired amount of liquid medicine  401  in the barrel  406 . A tubing  415  connected to the nozzle  408  is then shut off, by a valve or clip  417  attached on tubing  415  to seal the liquid medicine  401  in the syringe  40 . As such, the plunger  402  is prevented from moving relative to barrel  406 . 
         [0042]    In this embodiment, a seat  211  is attached to the slider  210 , and is rotatable relative to slider  210 . The advantages of seat  211  is to reduce torsional forces acting on the plunger  402  by the slider  210 , when the mandrel  101  is rotated into the telescopic sleeve  301 . However, the slider  210  may also be directly engaged to the plunger, without the presence of seat  211 . 
         [0043]    The plunger  402  is then inserted through entrance  307  of sleeve  301 , into hollow mandrel  101  ( FIGS. 6 and 7 (A)). After the plunger  402  and flange  403  pass through the entrance  307 , the barrel  406  of syringe  40  is twisted, by 90 degree for example, so that the oval-shaped flange  403  and similarly oval-shaped opening  309  are positioned with the longer axis of the flange  403  and the longer axis of the opening  309  aligned perpendicular to each other, to lock the barrel  406  to the sleeve  301 . Other forms and means of affixing the syringe of other configurations may be adopted which should not be considered to be excluded from the scope as defined by the claims appended thereafter. 
         [0044]    Once the barrel  406  is fixed to the sleeve  301 , as shown in  FIGS. 7(B), 7(C) and 7(D) , the mandrel  101  is rotated to move into the sleeve  301 , to bring the seat  211  of slider  210  into engagement with the plunger  402 . As the barrel  406  and plunger  402  are both relatively stationary with respect to the sleeve  301  since the valve or clip  417  is closed, further advancement of the mandrel  101  into the sleeve  301  will cause the slider  210  to move towards the closed end  103  of the mandrel  101 , resulting in the spring  215  being uncoiled and pulled out of the slider  210 , as shown in  FIG. 7(D) . 
         [0045]    With the spring  215  uncoiled, there stores a potential energy in the spring  215  which generates a driving force F 2  acting against the plunger  402 , as shown in  FIG. 8A . The apparatus  10  is now ready for delivering the fluid i.e. liquid medicine from the syringe  40  attached to the apparatus  10 . A shown in  FIG. 9 , when the valve or clip  417  is opened, driving force F 2  will prevail, which pushes the plunger  402  to move into the barrel  406  of syringe  40 , to expel the liquid medicine  401  out of the syringe  40  through nozzle  408 , to complete the fluid delivery. Throughout the whole process of fluid delivery, the driving force F 2  is maintained at a substantial constant value, which enables the fluid to be delivered under a contact flow rate. 
         [0046]    The slider  210  could be affixed with a magnetic sensor  252  that is in communication with a magnetic linear strip  254  attached on the adjacent channel  203  and/or  204  of housing  13 . Interaction of the sensor  252  and strip  254  could detect the position of the slider  210  relative to the mandrel  101 , which may be displayed on a screen  256  integrated on the apparatus  10  or onto a separate display  257  in signal communication with the sensor  252 . 
         [0047]    A shown in  FIGS. 10 and 11 , projections or stubs  221 ,  222 ,  223  and  224  may be formed at the corners of the slider  210  to create a clearance or gap  226  between the main body portion  210   a  of the slider  210  and the channels  203 ,  204  that allows displacement sensors  252  to be installed. The communication between the displacement sensor  252  and the display screen  256  or  257  can be established by Bluetooth, WiFi or direct cable connections. A skilled person in the art should be able to extrapolate the data on position and or displacement of the slider  210  relative to the channel  203 / 204  to obtain valuable information like flow rate at which the fluid is expelled, volume expelled and volume remaining in the syringe. With a built in data base of drug dose limits, commonly known as drug library, the aforesaid data could be used to provide alarms for patient risk situations related to overdose or under dose. 
         [0048]    Apparatus  10  may include a coupling element  209  positioned and connected between the slider  210  and the seat  211 . Coupling element  209  is configured to cause the first end  217  of spring  215  to be positioned at a distance away from the initial unstressed position of the spring  215  within the hollow mandrel  101 , such that the total distance the axis of the springs traveled is longer than the displacement required for the plunger  402  to fully discharge the fluid from the syringe. In principle, the length of the coupling element  209  is configured to be sufficient to cause the spring  215  to be uncoiled from the slider  210  so that the driving force F 2  exerted on the plunger  402  would have already reached its constant level when fluid start to flow. Typically this deflected length is about 1 to 1.5 times of the outer diameter of the spring  215  in coiled form. The coupling element  209  assists in generating a relatively more constant driving force acting on the fluid through the plunger, resulting in a relatively more constant flow profile during the fluid delivery, as shown in  FIG. 13 . 
         [0049]      FIG. 12  shows a system  80  for fluid delivery. The system  80  includes an array of docking stations  50  each being connected to a display unit  60  that is connected to a controller  70  via a direct or wireless communication network and power supply cable, for use in e.g. a patient centre for automated medication service. Each docking station  50  is configured to detachably hold an apparatus  10  and a syringe  40  attached to the apparatus  10  in a manner as illustrated above. In use, system  80  may be set up at a medical center or any suitable location for providing medication administration to patients. 
         [0050]    As shown in  FIG. 14 , a system  82  for fluid delivery includes one or more apparatus  10  as illustrated above, and a mobile platform  822  connected to each of the apparatus  10  with sensors and stripes installed thereon. Displacement of the slider in each apparatus and flow rate data can be communicated to the mobile platform via wireless network protocols such as Bluetooth, WiFi and/or GSM, which are monitored and controlled for to increase the applicability of the apparatus for medicament delivery to patients.