Patent Publication Number: US-2023133890-A1

Title: Living hinge seal for silicone-free syringe barrel

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 63/275,183, filed on Nov. 3, 2021 and titled, “Living Hinge Seal for Silicone-Free Syringe Barrel,” which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to medical devices. In some instances, the present disclosure relates to a lubrication-free syringe used to deliver fluid to or withdraw fluid from a patient. In some embodiments, the present disclosure relates to a syringe plunger having a tip seal configured to permit axial translation of a plunger within a lubrication-free syringe barrel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments disclosed herein will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. These drawings depict only typical embodiments, which will be described with additional specificity and detail through use of the accompanying drawings in which: 
         FIG.  1    is a perspective view of an embodiment of a syringe. 
         FIG.  2    is a perspective exploded view of the syringe of  FIG.  1   . 
         FIG.  3 A  is a perspective view of an embodiment of a syringe plunger of the syringe of  FIG.  1   . 
         FIG.  3 B  is a side view of the plunger of the syringe of  FIG.  1   . 
         FIG.  4 A  is a cross-sectional view of a plunger seal of the syringe plunger of  FIGS.  3 A and  3 B  in a formed state. 
         FIG.  4 B  is a cross-sectional view of the plunger seal of the syringe plunger of  FIGS.  3 A and  3 B  in a deflected state. 
         FIG.  5 A  is a perspective view of a portion of the syringe of  FIG.  1    with the plunger seal in a pressure state. 
         FIG.  5 B  is a perspective view of a portion of the syringe of  FIG.  1    with the plunger seal in a vacuum state. 
         FIG.  6    is a side view of an embodiment of a syringe barrel of the syringe of  FIG.  1   . 
         FIG.  6 A  is a perspective view of a proximal portion of the syringe barrel of  FIG.  6   . 
         FIG.  7    is side view of an embodiment of a syringe plunger injection mold. 
     
    
    
     DETAILED DESCRIPTION 
     A syringe may be used to deliver fluids to or withdraw fluids from a patient. In certain instances, some components of the syringe (e.g., barrel, plunger tip) are coated with a lubricant, such as silicone oil, to facilitate or ease axial translation of a plunger within the barrel. However, silicone oil or other lubricants can negatively react with certain medicaments disposed within the barrel. For example, particles comprising poly vinyl alcohol agglomerate when interacting with silicone oil, sodium tetradecyl sulfate foam is defoamed when interacting with silicone oil, and silicone oil has a negative effect when injected into the eye. 
     Embodiments herein describe embodiments of syringes free of a lubricant, such as silicone oil. In some embodiments within the scope of this disclosure, the syringe includes a barrel defining a reservoir, a syringe plunger, and a Luer lock fitting. The syringe plunger includes an integrally formed handle and a plunger tip disposed at a distal end of the handle. The plunger tip includes a wiper portion having two seals, a pressure seal and a vacuum seal, configured to sealingly engage with an internal surface of the barrel. A flexing hinge couples the wiper portion to a central portion of the plunger tip. The flexing hinge allows the wiper portion to be proximally deflected as the syringe plunger is inserted into the reservoir. The flexing hinge also allows the wiper portion to rock from a pressure state where the pressure seal seals against the internal surface of the barrel when the reservoir is pressurized by distal movement of the syringe plunger and a vacuum state where the vacuum seal seals against the internal surface of the barrel when a vacuum or negative pressure is formed in the reservoir by proximal movement of the syringe plunger. 
     The syringe plunger may be formed from a material having a low co-efficient of friction to allow the seals to slide against the internal surface of the barrel without adding a lubricant to the seals and/or the internal surface. For example, the syringe plunger may be formed from high density polyethylene (HDPE), polypropylene, nylon, low density polyethylene (LDPE), or polyoxy methylene (POM). Other materials are contemplated. In some embodiments, a syringe plunger formed from HDPE is gamma irradiated to reduce the co-efficient of friction relative to a non-irradiated syringe plunger. The syringe plunger may be formed using an injection molding process. In some such embodiments, a cavity of a mold used to form the syringe plunger has parting lines along a length of the handle and circumferentially at a proximal end of the plunger tip such that a parting line does not cross the seals to prevent mold flashing from forming across the seals. If the mold flashing were to cross the seals, the mold flashing may cause fluid leakage at the plunger tip adjacent the mold flashing. 
     The barrel may include detents formed at a proximal end following insertion of the syringe plunger. The barrel may also include a zero draft internal diameter where the internal diameter is equivalent at a proximal end and a distal end of the barrel. Furthermore, in some embodiments, the barrel is formed of a clear, rigid thermoplastic material, such as polycarbonate (PC), polypropylene, polystyrene, polypropylene, cyclo-olefin polymer (COP), cyclo-olefin copolymer (COC), amorphous nylon or glass. 
     Embodiments may be understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood by one of ordinary skill in the art having the benefit of this disclosure that the components of the embodiments, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of various embodiments, as represented in the figures, is not intended to limit the scope of the disclosure, but is merely representative of various embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated. 
     Reference throughout this specification to “an embodiment” or “the embodiment” means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment. 
       FIGS.  1  and  2    illustrate an embodiment of a syringe.  FIGS.  3 A and  3 B  illustrate an embodiment of a syringe plunger of the syringe.  FIGS.  4 A- 5 B  illustrate an embodiment of a plunger seal of the syringe plunger.  FIGS.  6  and  6 A  illustrate an embodiment of a syringe barrel of the syringe.  FIG.  7    illustrates an embodiment of a syringe plunger injection mold. In certain views each device may be coupled to, or shown with, additional components not included in every view. Further, in some views only selected components are illustrated, to provide detail into the relationship of the components. Some components may be shown in multiple views, but not discussed in connection with every view. Disclosure provided in connection with any figure is relevant and applicable to disclosure provided in connection with any other figure or embodiment. 
     As illustrated in  FIGS.  1  and  2   , a syringe  100  may be understood to include two broad groups of components; each group may have numerous subcomponents and parts. The two broad component groups are: a syringe plunger  110  and a syringe barrel  150 . In the illustrated embodiment, a Luer-lock nut  170  is coupled to a distal end of the syringe barrel  150  to form a male Luer-lock fitting. In some embodiments, the syringe barrel  150  and the Luer-lock nut  170  comprise a unibody construct. In other embodiments, a male Luer-slip fitting is disposed at the distal end of the syringe barrel  150 . Other coupling features or tips are likewise within the scope of this disclosure. 
     As illustrated in  FIGS.  3 A and  3 B , the syringe plunger  110  may comprise a plunger tip  120  and a handle  130 . The handle  130  may be a unibody construct formed by an injection molding manufacturing technique as described below. The material of the handle  130  can include any suitable material having a low coefficient of friction on glass or PC to facilitate sliding movement of the syringe plunger  110  within the syringe barrel  150  without use of a lubricant. For example, the static and/or kinetic coefficient of friction of the material of the handle  130  can be relatively low. In some embodiments, the static and kinetic coefficient of frictions may be substantially equivalent to prevent a stick-slip behavior where the plunger sticks to the syringe barrel  150  and then suddenly slips. Examples of suitable materials include HDPE, polypropylene, nylon, LDPE, or POM. Other materials are contemplated. 
     The handle  130  of the depicted embodiment includes a thumb pad  131  disposed at a proximal end of the handle  130 . The thumb pad  131  may be used to manipulate the syringe plunger  110  relative to the syringe barrel  150  to inject a fluid, such as a medicament, from the syringe barrel  150  or to draw the fluid into the syringe barrel  150 . A proximal surface of the thumb pad  131  can include features to enhance a user&#39;s interaction with the thumb pad  131 . The features may include ribs, grooves, bumps, divots, surface texturing, etc. In other embodiments, the thumb pad  131  may be a ring configured to receive a user&#39;s digit, such as a thumb. 
     In some embodiments, a plurality of ribs  132  are disposed between the thumb pad  131  and the plunger tip  120 . The number of ribs  132  may be three, four, five, six, or more. In another embodiment, the handle  130  may include an elongate cylinder disposed between the thumb pad  130  and the plunger tip  120 . A width of the handle  130  transversely across the ribs  132  may be smaller than a diameter of a bore  157  of the syringe barrel  150  such that the ribs  132  help to maintain co-axial alignment of the plunger tip  120  with the bore  157  of the syringe barrel  150 . For example, the width of the handle may be from about 0.10 millimeter to about 0.25 millimeter smaller than the diameter of the bore  157 . This configuration may be configured to help to ensure substantial equal circumferential sealing of the plunger tip seals  123 ,  124  with an internal surface  156  of the syringe barrel  150 . 
     A proximal alignment disk  133  and a distal alignment disk  134  can be disposed at a distal portion of the handle  130  adjacent or near the plunger tip  120 . The disks  133 ,  134  may be longitudinally spaced apart and have a diameter substantially equivalent to the diameter of the handle  130 , such that the disks  133 ,  134  help to maintain co-axial alignment of the plunger tip  120  with the bore  157  of the syringe barrel  150 . This configuration helps to ensure substantial equal circumferential sealing of the plunger tip seals  123 ,  124  with an internal surface  156  of the syringe barrel  150 . 
     In the illustrated embodiment, as shown in  FIGS.  3 A and  3 B , the plunger tip  120  is coupled to and disposed at a distal end of the handle  130 . The plunger tip  120  is configured to slidingly seal against the internal surface  156  of the barrel  150  without the use of a lubricant. In the embodiment illustrated in  FIG.  4 A , the plunger tip  120  includes a wiper  121 , a hinge  122 , and a central portion  126 . The central portion  126  is in axial alignment with the handle  130 . The hinge  122  is circumferentially coupled to the central portion  126 . The hinge  122  includes a circumferential necked down portion  127  such that the hinge  122  is configured to flex proximally and distally relative to a longitudinal axis of the syringe plunger  110 . The necked down portion  127  may have a thickness ranging from about 0.2 millimeter to about 0.8 millimeter. 
     The wiper  121  extends radially outward from the hinge  122 . The wiper  121  includes a circumferential distal seal  123 , a circumferential proximal seal  124 , and a circumferential recess  125  disposed between the distal seal  123  and the proximal seal  124 . A distal surface  128  of the wiper  121  includes an angle α ranging from about 30 degrees to about 80 degrees relative to the longitudinal axis of the syringe plunger  110  as shown in  FIG.  4 A , prior to insertion of the syringe plunger  110  into the bore  157  of the syringe barrel  150 . The wiper  121  may be proximally deflected, as shown in  FIG.  4 B , when the syringe plunger  110  is inserted into the bore  157  as the wiper  121  engages with the internal surface  156  of the bore  157  to ensure sealing engagement of the seals  123 ,  124  with the internal surface  156 . The angle α may range from about 5 degrees to about 30 degrees following insertion of the plunger tip  120  into the bore  157 . An outside diameter D of the wiper  121  (measurement D shown in  FIG.  3 B ) can be larger than the diameter of the bore  157 . 
     As depicted in the embodiment of  FIG.  4 A , the distal seal  123  includes a convex radius r 1 . The proximal seal  124  includes a convex radius r 2 . The seals  123 ,  124  are disposed at an angle β relative to the longitudinal axis of the syringe plunger  110  prior to insertion of the plunger tip  120  into the bore  157 , as shown in  FIG.  4 A . The seals  123 ,  124  are disposed substantially parallel to the longitudinal axis of the syringe plunger  110  following deflection of the hinge  122  when the plunger tip  120  is inserted into the bore  157 , as shown in  FIG.  4 B . The recess  125  is disposed between the seals  123 ,  124  and has a depth relative to a tangent line between the seals  123 ,  124  ranging from about 0.05 millimeter to about 0.4 millimeter. 
       FIGS.  5 A and  5 B  illustrate the plunger tip  120  in a vacuum state and a pressure state, respectively. As shown in  FIG.  5 A , when the plunger tip  120  is displaced proximally, direction of arrow, within the bore  157  of the syringe barrel  150 , a vacuum or negative pressure can be generated within the bore  157  distal of the plunger tip  120 . When the vacuum is generated, the wiper  121  may be displaced or flexed distally about the hinge  122  such that the proximal seal  124  is biased toward the internal surface  156  to ensure sealing engagement of the proximal seal  124  with the internal surface  156 . As shown in  FIG.  5 B , when the plunger tip  120  is displaced distally, direction of arrow, within the bore  157  of the syringe barrel  150 , a positive pressure can be generated within the bore  157  distal of the plunger tip  120 . When the positive pressure is generated, the wiper  121  may be displaced or flexed proximally about the hinge  122  such that the distal seal  123  is biased toward the internal surface  156  to ensure sealing engagement of the distal seal  123  with the internal surface  156 . 
       FIGS.  6  and  6 A  illustrate an embodiment of the syringe barrel  150 . The syringe barrel  150  can be formed as a unibody construct using any suitable technique, such as injection molding, 3D printing, machining, over-molding, etc. The syringe barrel  150  may be formed of any suitable transparent or translucent rigid or semi-rigid material. For example, the material of the syringe barrel  150  can be glass, PC, polypropylene, cyclo-olefin polymer (COP), cyclo-olefin copolymer (COC), or amorphous nylon. Other materials are contemplated. As illustrated, the syringe barrel  150  includes an elongate, tubular body  151  having an internal surface  156  that defines the bore  157  extending therethrough. The bore  157  is configured as a reservoir to contain fluid, such as a medicament to be injected into a patient. A male Luer fitting  153  is disposed at a distal end of the body  151  and is in fluid communication with the bore  157 . The male Luer-lock nut  170  may be coupled to the male Luer fitting  153  as shown in  FIG.  1   . A flange  152  is disposed at a proximal end of the body  151 . The flange  152  extends radially outward from the body  151  and can be used to grip the syringe barrel  150  during use. 
     As depicted, the body  151  includes an internal detent  154  disposed adjacent the proximal end to retain the syringe plunger  110  within the bore  157 . The number of detents  154  may be one, two, three, four, or more that are spaced equidistantly around a circumference of the body  151 . A height of the detent  154  may range from about 2.0 millimeters to about 2.5 millimeters from the internal surface  156 . In other words, the proximal disk  133  has a diameter larger than a transverse distance between the detents  154  such that the proximal disk  133  can engage the detents  154  when the syringe plunger  110  is displaced proximally to prevent the syringe plunger  110  from inadvertently being removed from the syringe barrel  150 . The detent  154  can include a rectangular, circular, or dome shape. Other shapes are contemplated. The detent  154  may be formed in the body  151  following insertion of the plunger tip  120  into the bore  157  using pressure and/or heat applied by a detent forming tool. 
       FIG.  7    illustrates an embodiment of an injection mold  200  that may be used to form the syringe plunger  110 . As illustrated, the injection mold  200  may include an upper mold portion  201 , a lower mold portion  202 , a slide portion  204 , and a cavity  206 . The cavity  206  includes a handle portion  207  disposed within the upper mold portion  201  and the lower mold portion  202 . The handle portion  207  includes a negative shape of the handle  130  of the syringe plunger  110  to receive molten material to form the handle  130  as previously described. A longitudinal parting line  203  divides the upper mold portion  210  from the lower mold portion  202  and extends along a longitudinal axis of the handle portion  207 . 
     A plunger tip portion  208  of the cavity  205  may be disposed within the slide portion  204 . The plunger tip portion  208  includes a negative shape of the plunger tip  120  of the syringe plunger  110 . A vertical parting line  205  divides the slide portion  204  from the upper and lower mold portions  201 ,  202 . Thus, the plunger tip portion  208  may be configured such that the vertical parting line  205  does not cross into the plunger tip portion  208  of the cavity  206 . 
     In use, molten material is injected into the cavity  206  to form the syringe plunger  110 . Following cooling of the molten material, the upper mold portion  201  is separated from the lower mold portion  202  along the parting line  203  releasing the handle  130  of the syringe plunger  110  from the handle portion  207  of the cavity  206 , as indicated by the arrows. The upper and lower mold portions  201 ,  202  are also moved along the vertical parting line  205  to expose a proximal surface of the plunger tip  120  of the syringe plunger  110 . The slide portion  204  is moved away from the upper mold portion  201  and the lower mold portion  202 , as indicated by the arrow. The plunger tip  120  is ejected from the plunger tip portion  208 . The formed plunger tip  120  is free of mold flashing across the seals  123 ,  124  because the vertical parting line  205  did not cross the seals  123 ,  124 . This design may be configured to prevent leakage around the plunger tip  120 . Mold flashing crossing the seals  123 ,  124  may prevent the plunger tip  120  from sealing with the internal surface  156  of the syringe barrel  150 . In other words, mold flashing on the seals  123 ,  124  may allow fluid to leak around the plunger tip  120 . Thus, embodiments wherein the seals  123 ,  124  are free of mold flashing may be configured to facilitate sealing. 
     Any methods disclosed herein comprise one or more steps or actions for performing the described method. The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified. For example, a method of manufacturing a syringe plunger may include one or more of the following steps: injecting a molten material into a cavity of the mold; wherein the cavity comprises a syringe plunger shaped void comprising: a plunger tip portion comprising a first seal portion and a second seal portion, and a plunger handle portion, a longitudinal parting line extending proximally of a plunger tip portion of the cavity, and a circumferential parting line disposed proximally of the plunger tip portion; parting the mold along the longitudinal parting line; and ejecting a plunger tip of a molded syringe plunger from the plunger tip portion of the cavity, wherein the plunger tip is free of molding flashing extending longitudinally across a first seal and a second seal of the plunger tip. Other steps are also contemplated. 
     In the above description of embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim requires more features than those expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment. 
     It will be appreciated that various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure. Many of these features may be used alone and/or in combination with one another. 
     The phrases “coupled to” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be coupled to or in communication with each other even though they are not in direct contact with each other. For example, two components may be coupled to or in communication with each other through an intermediate component. 
     The directional terms “distal” and “proximal” are given their ordinary meaning in the art. That is, the distal end of a medical device means the end of the device furthest from the practitioner during use. The proximal end refers to the opposite end, or the end nearest to the practitioner during use. 
     “Fluid” is used in its broadest sense, to refer to any fluid, including both liquids and gases as well as solutions, compounds, suspensions, body fluids, etc., which generally behave as fluids. 
     References to approximations are made throughout this specification, such as by use of the term “substantially.” For each such reference, it is to be understood that, in some embodiments, the value, feature, or characteristic may be specified without approximation. For example, where qualifiers such as “about” and “substantially” are used, these terms include within their scope the qualified words in the absence of their qualifiers. For example, where the term “substantially equivalent” is recited with respect to a feature, it is understood that in further embodiments, the feature can have a precisely equivalent configuration. 
     The terms “a” and “an” can be described as one, but not limited to one. For example, although the disclosure may recite a housing having “a stopper,” the disclosure also contemplates that the housing can have two or more stoppers. 
     Unless otherwise stated, all ranges include both endpoints and all numbers between the endpoints. 
     Recitation in the claims of the term “first” with respect to a feature or element does not necessarily imply the existence of a second or additional such feature or element. 
     The claims following this written disclosure are hereby expressly incorporated into the present written disclosure, with each claim standing on its own as a separate embodiment. This disclosure includes all permutations of the independent claims with their dependent claims. Moreover, additional embodiments capable of derivation from the independent and dependent claims that follow are also expressly incorporated into the present written description. 
     Without further elaboration, it is believed that one skilled in the art can use the preceding description to utilize the invention to its fullest extent. The claims and embodiments disclosed herein are to be construed as merely illustrative and exemplary, and not a limitation of the scope of the present disclosure in any way. It will be apparent to those having ordinary skill in the art, with the aid of the present disclosure, that changes may be made to the details of the above-described embodiments without departing from the underlying principles of the disclosure herein. In other words, various modifications and improvements of the embodiments specifically disclosed in the description above are within the scope of the appended claims. Moreover, the order of the steps or actions of the methods disclosed herein may be changed by those skilled in the art without departing from the scope of the present disclosure. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order or use of specific steps or actions may be modified. The scope of the invention is therefore defined by the following claims and their equivalents.