DESC:FIELD

The present disclosure relates generally to plungers for use in syringes. More particularly, the present disclosure relates to plungers having an improved plunger top for use in syringes and methods related thereto. The disclosure also relates to an improved plunger rod adapted for attachment with a plunger assembly. The syringes include prefilled or non-filled syringes.

BACKGROUND

Syringes for example, pre-filled syringes, are usually used in flush applications. Such pre-filled syringes are typically filled with a saline solution and are used to flush catheters. During use, the nurse or medical professional “bottoms out” the plunger top in the syringe barrel at the end of the flushing procedure. The process of bottoming out the plunger top in the barrel may cause a phenomenon known as reflux. Reflux is the reversal of fluid flow up through the catheter, usually due to the spring back of the plunger top at the end of a flush injection. Reflux may occur when the plunger top compresses to force out additional saline and subsequently springs back to shape, causing saline to be pulled back into the syringe. Reflux can also pull blood back into the catheter, clogging it. This phenomenon of reflux may be detrimental to the maintenance of the catheter line.

Thus, plungers having a plunger top are a critical component of any syringe for example any prefilled syringe, because they must demonstrate both perfect Plunger Barrel Seal Integrity (PBSI) and flawless gliding behavior. This ensures that syringe contents are administered safely and consistently to patients even after several years of storage.

Existing syringe plungers designs have attempted to prevent the flow of fluid from the catheter back into the syringe, a phenomenon known as reflux, which can occur when the stopper or plunger top compresses to force out additional fluid or saline and subsequently springs back to shape, causing the syringe to pull fluid or saline back into the syringe. While effective in reducing reflux, these designs do not consistently prevent all reflux from occurring. Further still, many of these designs include a significant amount of dead space volume. The dead space volume in some plunger designs can harbor contaminants and make sterilization more difficult. A plunger that minimizes dead space and enhances sterility would be beneficial.

Many syringe plungers do not provide a consistent, reliable seal within the syringe barrel. This can lead to leakage, inaccurate fluid delivery, and potential contamination. The assembly of some syringe plunger components can be complex and labor-intensive, making large-scale manufacturing challenging. A plunger design that simplifies the assembly process would be advantageous. Further, existing plunger designs may have limited ability to be customized for different syringe sizes, materials or applications. A more versatile plunger design that can be easily adapted would expand the range of uses.

To address these issues, a number of syringe plungers and methods of fabrication thereof have been developed. However, there remains a need for improved syringe plungers and methods of fabrication thereof that can further reduce or eliminate reflux within the syringe. A plunger top for a syringe that creates an effective seal within the syringe barrel and effectively addresses the issue of dead space volume is also desirable. Thus, the present disclosure aims to provide an improved syringe plunger that enhances performance, simplifies manufacturing, and offers great versatility compared to existing solutions.

OBJECTS AND SUMMARY:

Certain exemplary aspects and examples of the present disclosure are provided below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the disclosure might take and that these aspects are not intended to limit the scope of the disclosure. Indeed, the invention may encompass a variety of aspects and examples that may not be set forth below. The illustrations and variations described herein are meant to provide examples of the devices and methods of disclosure. It is contemplated that combinations of aspects of specific embodiments and/or examples or variations or combinations of the specific embodiments and/or examples or variations are within the scope of this disclosure.

One of the objects of the present disclosure is to provide an improved plunger with a plunger top which achieves a “positively zero” or an essentially zero reflux which meets the ISO standard for dead space. This is particularly important in the context of medical syringes, where the prevention of reflux is crucial to ensure accurate and reliable fluid delivery. The plunger top is designed with a specific geometry and material selection to achieve a “positively zero” or essentially zero reflux, meeting the ISO standard for dead space.

Another object of the present disclosure is to provide an improved plunger with a plunger top which achieves an effective and active seal within a syringe barrel. The concept of an active seal involves an increase in pressure inside the syringe barrel which will cause the forward seal of the plunger top to have a higher contact pressure with the inside walls of the barrel, maintaining a higher contact pressure than the internal fluid pressure, thereby preventing leakage at the plunger top seal. The active seal mechanism of the present disclosure works by leveraging the increase in pressure inside the syringe barrel during use. As the pressure rises, the forward seal of the plunger top experiences a corresponding increase in contact pressure, maintaining this higher contact pressure even as the internal fluid pressure continues to build. The ensures the seal is able to reliably contain the fluid within the syringe, preventing any leakage or spillage. The active seal design of the present disclosure provides more consistent and predictable sealing performance that is less affected by variations in fluid properties or environmental conditions.

Another object of the present disclosure is to provide an improved plunger with a plunger top which ensures that syringe contents are administered safely and consistently to patients even after several years of storage.

Another object of the present disclosure is to provide an improved plunger with a plunger top which ensures effectively reducing and/or eliminating reflux of fluid back into the syringe upon the release of pressure on the plunger rod.

Another object of the present disclosure is to provide a plunger rod attachment design that can be easily inserted into the plunger top of a pre-filled, sterilized syringe with the application of minimal force thereto and which is securely held within the plunger top during use in the syringe.

Yet another object of the present disclosure is to provide a plunger rod that can be easily assembled with and/or inserted into the plunger top with ease and which ensure secure engagement of the plunger rod with the plunger top during use within the syringe.

In some examples of the present disclosure, there is provided a syringe having an improved plunger design, with a plunger top having features to provide minimum gliding force and maximize the vortex effect during use. The syringe comprises a plunger rod, a plunger having a plunger top, a syringe barrel and a tip closure member. The improved plunger with a plunger top is designed with at least two sealing rings that help create a reliable seal integrity while also maintain the gliding force required to operate the plunger within the syringe barrel. The improved plunger top incorporates a conical tip to create and maximize the vortex effect, when the plunger is subjected to spin within the syringe barrel or a transparent container for example made of plastic, glass or any transparent container vial with or without solution. The conical angle of the plunger top helps in increasing the centrifugal throw which converts into a vortex. The specific conical angle(s) of the plunger top helps increase the centrifugal throw, converting it into a vortex and enhancing the mixing and agitation of the fluid within the container. The combination of the sealing rings and the conical tip has advantages. The minimum gliding force ensures that the plunger can be operated with ease requiring less effort from a user, which can be particularly beneficial in medical and healthcare settings where precise control and dexterity are crucial. The vortex effect created by the conical tip is advantageous in various applications, such as reconstituting powdered medications or ensuring through mixing of solutions prior to administration. The enhanced agitation and mixing can help improve the homogeneity of the fluid, leading to more accurate and reliable dosing.

In some examples of the present disclosure, there is provided a plunger having a plunger top adapted for attachment with a plunger rod for use within a syringe barrel of a syringe, said plunger top comprises: a main body that defines an open proximal or rear end and a closed distal or front end. The main body is designed with at least two sealing rings that form an outer contact and sealing area with an inner wall of the syringe barrel when the plunger top is slidably arranged within the syringe barrel. The main body of the plunger top incorporates at least one arch area or a change in profile area in between the two-sealing ring(s). The arch or change in profile area helps to create a more effective and reliable seal between the plunger top and the inner wall of the syringe barrel. The varying geometry in this region allows the sealing rings to conform better to the barrel’s surface, enhancing the overall sealing integrity. Additionally, the arch or change in profile area helps to reduce the gliding force required to move the plunger top within the syringe barrel minimizing the friction and resistance experienced during the plunger’s movement improving the overall ease of the use and control by the user.

In some examples of the present disclosure, the plunger top includes a main body having a unitary structure. The unitary design ensures that the various features and elements of the plunger top, such as the sealing rings, arch or change in profile areas, and the overall shape, are precisely aligned and integrated, contributing to the overall performance and reliability of the plunger during use. In some examples, the plunger top may be fabricated in parts or having one or more parts which may be assembled together, for example, the part forming conical tip may form one part and the body underneath the conical tip of the plunger top may form another part. This modular approach may provide additional flexibility in the manufacturing process, allowing for the use of different materials or the incorporation of specialized features in specific components of the plunger top.

In some examples of the present disclosure, the plunger top comprises a main body with a conical tip that has both an inner angle and an outer angle. In some examples, the inner angle(s) forming the conical tip of the plunger top is at least more than 90°, creating a relatively obtuse conical shape and edges. Additionally, the edges of the conical tip are designed to be rounded, rather than sharp edges. The obtuse inner angle, greater than 90° helps to reduce the friction experienced by the plunger top as it moves within the syringe barrel. The rounded edges further contribute to this reduced friction, providing a smoother movement being more effortless movement of the plunger top within the syringe barrel during use. In some examples, the inner angle forming the conical tip of the plunger top is at least more than 100°. In some examples, the inner angle forming the conical tip of the plunger top is at least more than 120°.

In some examples of the present disclosure, the plunger top comprises a main body with a conical tip that has both an inner angle and an outer angle. In some examples, the outer angle(s) forming the conical tip of the plunger top is at least more than 10°. In some examples, the outer angle forming the conical tip of the plunger top is at least more than 20°. The combination of the inner and outer angle(s) of the conical tip creates a unique outer surface geometry. The combination of the inner and outer angle(s) of the conical tip creates a unique surface geometry that optimizes the plunger top’s performance in various applications, such as pre-filled syringes. The larger surface area of the conical tip, achieved through the specific combination of inner and outer angle(s), helps to distribute the pressure more evenly during the flushing procedure. Such a pressure distribution leads to a reduction in the overall pressure experienced by the liquid, making the flushing process smoother and more controlled. The specific angle ranges outlined in these and above examples are designed to optimize the performance of the plunger top, taking into account factors such as fluid dynamics, material properties, and manufacturing considerations. However, it is to be understood that the inner and outer angle(s) forming the conical tip is not limited to these specific examples and may vary. The present disclosure intends to encompass a broader or varying range of inner and outer angle(s) that may be used to achieve the desired performance characteristics. The inner and outer angle(s) may vary depending on factors such as the material properties of the plunger top, the syringe barrel, and the specific applications.

In some examples of the present disclosure, the plunger top includes a main body having at least two sealing ring(s) that form the outer contact and sealing area with the inner wall of the syringe barrel when the plunger top is slidably arranged within the syringe barrel. In some examples, the sealing ring(s) are designed to have an equal dimensional width as seen in an axial direction. This symmetrical approach ensures that the sealing ring(s) provide a consistent and uniform contact with the inner wall of the syringe barrel, creating an effective and reliable seal. This symmetrical approach has several advantages, including consistent sealing pressure around the circumference of the barrel to minimize the risk of leaks, smooth and stable movement of the plunger top during operation, and easier manufacturing and assembly since the sealing rings are identical.

In some examples, the sealing ring(s) may be formed with non-equal dimensional widths as seen in the axial direction. The varying widths of the sealing ring(s) may be tailored to optimize factors such as sealing integrity, fluid dynamics, or the interaction between the plunger top and the syringe barrel.

In some examples of the present disclosure, the plunger top includes a main body having at least two sealing rings wherein dimensional width as seen in an axial direction of at least one of the sealing rings is greater than the other sealing ring. The ability to adjust the relative widths of the sealing rings allows for more precise fitting and adaptation to different housing geometries.

In some examples of the present disclosure, the plunger top includes a main body having an arch area or a change in profile area preferably in between the two-sealing ring(s) to reduce friction, prevent leakage of fluid and reduce break loose forces of the outer contact and sealing area of the plunger top with respect to the inner wall of the syringe barrel. The arch area or change in profile area of the plunger top has slightly curved profile and compressed in form for less contact area with the inner wall of the syringe barrel which further helps in reducing friction forces. Further, the arch area or change in profile area is configured to enhance and give more strength to the plunger top.

In some examples of the present disclosure, the plunger top includes a main body having a first undercut profile being proximal to and underneath the conical tip which prevents detachment of the plunger top while pulling the plunger rod wherein the tip end of the plunger rod forming a lock feature is fixedly received within the first undercut. The plunger top is further provided with a second undercut proximal to and underneath the first undercut. The plunger top is further provided with a third undercut proximal to and underneath the second undercut wherein the walls forming an inner periphery of the third undercut have angled profile for smooth assembly and entry of the plunger top with the plunger rod. As such, when the plunger top is assembled with the plunger rod, the distal end profile of the plunger rod is fixedly received within said first, second and third undercuts, ensuring that the plunger top remains securely attached to the plunger rod, preventing any detachment of the plunger top with the plunger rod.

In some examples of the present disclosure, the plunger top includes a main body having a proximal face wherein one or more projections are provided so that the plunger top when assembled on the plunger rod does not stick to the plunger rod. In addition, said one or more projections helps in enhancing the sealing of the plunger top with the plunger rod. In some examples, the proximal face of the plunger top is provided with at least two projections.

In some examples of the present disclosure, the plunger top includes a main body wherein the proximal face of the plunger top is having a diameter which is at least two times greater than the height of the plunger top in axial direction which further helps in reducing friction forces.

In some examples of the present disclosure, the plunger rod being an elongated plunger rod body has a proximal and distal end wherein the proximal end of the plunger rod includes a circular base profile which helps in pulling or pushing of the plunger rod from or within the syringe barrel. The distal end of the plunger rod forms a locking profile or front attachment end which is fixedly received having a matching shape and configuration within the first, second and third undercuts of the plunger top which prevents detachment of the plunger top when assembled over the plunger rod. When the locking profile or front attachment end of the plunger rod enters the undercut space, the plunger rod is locked in place and is prevented from separating from the plunger top. In addition, the plunger rod is provided with one or more ribs to provide strength as well as to make the plunger rod lighter in configuration having improved gliding features within the syringe barrel during use.

In some examples, the plunger top or stopper design of the present disclosure is intended to prevent reflux by creating a gap between the back portion of the flexible core member of the plunger top or stopper and the face of the front forward end attachment portion of the plunger rod. Due to this gap and the flexibility of the flexible membrane attaching the flexible core member to the plunger top or stopper main body, the flexible core member is able to deflect proximally and store potential energy that is released in the form of positive displacement as soon as the plunger rod force is ceased, preventing mid-stream reflux.

In some examples, the plunger rod is provided having a design which allows for easy assembly and secure engagement with the plunger top. The plunger rod is designed with a specific geometry and features that facilitate a seamless and intuitive connection with the plunger top. This could involve the use of complementary shapes, such as a tapered or stepped interface, that guides the plunger rod into the plunger top and ensures a tight, secure fit. Additionally, the plunger rod may incorporate locking mechanisms, such as snap-fit features or threaded connections, that provide a robust and reliable engagement with the plunger top, preventing any unintended separation during use. The design features incorporated into the plunger rod create a strong, durable connection that can withstand the various forces and pressures encountered during the fluid delivery process. This secure engagement helps to maintain the integrity of the plunger assembly, preventing any unwanted separation or displacement of the plunger rod, which could compromise the accuracy and safety of the fluid delivery.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS:

The foregoing and other objects, features, and advantages of the present disclosure will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which like reference numerals refer to like parts throughout, wherein:

FIGS. 1A & 1B illustrate a front and perspective view respectively of an improved plunger with a plunger top of according to some examples of the present disclosure;

FIG. 1C illustrates a cross-sectional view of the improved plunger with a plunger top of Figs. 1A & 1B;

FIG. 1D illustrates a top view of the improved plunger with a plunger top of Figs. 1A & 1B;

FIGS. 1E & 1F illustrate a bottom and bottom perspective view respectively of the improved plunger with a plunger top of Figs. 1A & 1B;

FIGS. 2A & 2B illustrate a perspective and side view respectively of a plunger rod with the plunger top of Figs. 1A and 1B;

FIG. 3A illustrates a schematic cross-sectional view of a plunger rod, plunger top, syringe barrel and tip closure member in accordance with some examples of the present disclosure;

FIG. 3B illustrates a schematic side view of a plunger rod, plunger top, syringe barrel and tip closure member in accordance with some examples of the present disclosure;

FIG. 3C illustrates a perspective view of a plunger rod, plunger top, syringe barrel and tip closure member in accordance with some examples of the present disclosure.

DETAILED DESCRIPTION:

Embodiments and/or examples of the present disclosure will now be described in detail with reference to the drawings wherein like reference numerals designate identical or corresponding elements. In the drawings and in the description, the term "proximal", "bottom", "down" or "lower" or “rear” refers to a location on the device that is closest to a user using the device and farthest from an end user i.e. who is being pierced by the piercing device i.e. in connection with whom the device is used when the device is used in its normal operation. Conversely, the term "distal", "top", "up" or "upper" refers to a location on the device that is farthest from the clinician using the device and closest to the patient in connection with whom the device is used when the device is used in its normal operation. For example, the distal region of a needle will be the region of the needle containing the needle tip which is to be inserted e.g. into an end user’s earlobe.

As used herein, the terms first, second, third, etc. are understood to describe different structures/elements so as to distinguish one from another. However, the terms are not structurally limiting unless the context indicates otherwise.

The term "substantially" means that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect of the characteristic it intended to provide.

Moreover, the Figures may show simplified or partial views, and the dimensions of elements in the Figures may be exaggerated or otherwise not in proportion for clarity. In addition, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a terminal includes reference to one or more terminals. In addition, where reference is made to a list of elements (e.g., elements a, b, c), such reference is intended to include any one of the listed elements by itself, any combination of less than all of the listed elements, and/or a combination of all of the listed elements.

Further, for purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, “longitudinal”, and derivatives thereof shall relate to the disclosure as it is oriented in the drawing figures. However, it is to be understood that the disclosure may assume various alternative variations, except where expressly specified to the contrary. It is also to be understood that the specific devices illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments and/or examples of the disclosure. Hence, specific dimensions and other physical characteristics related to the embodiments and/or examples disclosed herein are not to be considered as limiting.

Reference is now made to Figs. 1A to 1F, wherein some examples of a plunger 10 including an improved plunger top 12 of the present disclosure is illustrated. As illustrated in FIGS. 1A and 1F, plunger top 12 comprises a main body 12a defining an open proximal or rear end 24 and a closed distal or front end 22. The open proximal or rear end 24 of the plunger top 12 is configured to receive an attachment tip end 40 portion of a plunger rod 14 as shown in Fig. 3A. The open proximal or rear end 24 of the plunger top 12 is defined by an inside wall surface and is adapted for receiving the front attachment tip end 40 portion of the plunger rod 14 and locking the plunger rod 14 securely within the plunger top 12.

The plunger 10 including the improved plunger top 12 having an outer surface area 28 that contacts the fluid within a syringe 16 as illustrated in Fig. 3A and forms a seal with the inner wall 32 of the generally cylindrical barrel 18 of syringe 16 during use. While the figures herein depict a separate plunger top 12, it is contemplated that the plunger top 12 may be fixedly received on plunger rod 14 or integrally formed with a plunger rod 14 for use with a syringe 16 as shown in Fig. 3A. Thus, the plunger top 12 as shown in Fig. 3A is adapted for attachment with a plunger rod 14 for use within a syringe barrel 18. The plunger top 12 is preferably made of an elastomeric material selected from the group of thermoplastic elastomers, non-porous rubber material, natural rubber, synthetic rubber, thermoplastic vulcanizates (TPV) and/or combinations thereof. The plunger top 12 of the disclosure is particularly useful with flush syringes i.e. pre-filled syringes such as those for use in connection with a catheter, as is well known in the art. However, it is to be understood that the plunger top 12 of the disclosure can also be used with a non-filled syringe 16.

As shown in Fig. 1A, the plunger top 12 includes a main body 12a having a unitary structure. The plunger top 12 having a conical tip 26 configured to enter within an open proximal or rear end 24 of a syringe barrel 18 as shown in Fig. 3A. The formation of conical tip 26 is defined by an inner and an outer angle. Inner angle(s) forming the conical tip 26 of the plunger top 12 is at least more than 90° which helps in reducing friction and provide smooth movement of the plunger top 12 within the syringe barrel 18. Further, the outer angle(s) forming the conical tip 26 of the plunger top 12 is at least more than 10°. A combination of the inner and outer angle(s) of the conical tip 26 creates an outer surface area 28 providing more and/or greater contact area with the liquid for example of a pre-filled syringe and helps in reducing pressure in flushing procedure.

As shown in Fig. 1C, the plunger top 12 has at least two sealing rings 30a, 30b, preferably having equal dimensional width as seen in an axial direction A. In some examples, the sealing rings 30a, 30b may be formed having non-equal dimensional width as seen in the axial direction A. Said at least two sealing ring(s) 30a, 30b form the outer contact and sealing area with the inner wall 32 of the syringe barrel 18 when the plunger top 12 is slidably arranged within the syringe barrel 18 of the syringe 16 as shown in Fig. 3A. A proximal end part of the second sealing ring 30b has a curved profile 34b which further helps in reducing friction.

As shown in Figs. 1A, 1B and 1C, the plunger top 12 has at least one arch area or a change in profile area 36 in between the two-sealing ring(s) 30a, 30b to reduce friction, prevent leakage of fluid and reduce break loose forces of the outer contact and sealing area of the plunger top i.e. in particularly of the sealing ring(s) 30a, 30b with respect to the inner wall 32 of the syringe barrel 18 as shown in Fig. 3A. The arch area or change in profile area 36 of the plunger top 12 has a slightly curved profile 34a and compressed in form creating less contact area with the inner wall 32 of the syringe barrel 18 which further helps in reducing friction forces. Further, the arch area or change in profile area 36 is configured to enhance and give more strength to the plunger top 12 during use in the syringe 16.

Further, the conical tip 26 of the plunger top 12 includes a tip end 76 that is substantially centered within the shape of the conical tip 26. The outer surface area 28 of the conical tip 26 portion has a sloped outer surface that extends from the distal end of the first sealing ring 30a all the way to the tip end 76 of the conical tip 26. This sloped surface facilitates zero reflux and minimizes the dead space within the syringe 16 during use. The conical shape of the tip 26 is not limited to a strictly conical form but may also include other volumetric shapes that are capable of self-centering with respect to the opening or outlet 74 of the syringe barrel 18. Such alternative shapes may include substantially conical, spheroid, ellipsoid, cubic, and/or any other shape that allows the plunger top 12 to properly align and seal with the syringe barrel 18.

Referring to Fig. 1C, the plunger top 12 has a first undercut 38a profile being proximal to and underneath the conical tip 26 which prevents detachment of the plunger top 12 once assembled with the plunger rod 14 for example, while pulling the plunger rod 14 (as shown in Fig. 3A) wherein the tip end 40 of the plunger rod 14 forming a lock feature which is fixedly received within the first undercut 38a. At the same time, the first undercut 38 profile provides support to create adequate pressure to the conical tip 26 during use in the syringe 16. The first undercut 38 profile provides, thus, provides structural support to the conical tip 26, allowing it to generate adequate pressure during use in the syringe 16. The undercut design creates a tight fit between the plunger top 12 and rod 14, while also reinforcing the conical tip 26 to optimize its sealing performance within the syringe barrel.

The plunger top 12 is further provided with a second undercut 38b located proximally and underneath the first undercut 38a. The plunger top 12 is further provided with a third undercut 38c that is proximal to and underneath the second undercut 38b. The third undercut 38c having an inner periphery defined by walls 42 wherein walls 42 that have an angled profile for smooth assembly of the plunger top 12 with the plunger rod 14. As such, when the plunger top 12 is assembled with the plunger rod 14 as shown in Fig. 3A, a distal attachment end 40 profile of the plunger rod 14 is fixedly received within said first 38a, second 38b and third 38c undercuts preventing detachment of the plunger top 12 from the plunger rod 14 during use conditions. Each of the first 38a, second 38b and third 38c has a specific width dimension that contributes to the overall structural integrity and assembly of the plunger system. As can be seen, the width of the first undercut 38a is greater than the widths of the second 38b and third 38c. Such a graduated undercut profile, with the largest undercut closest to the conical tip 26, provides optimal structural support and attachment strength to the plunger top 12. However, in some examples, varying and/or similar dimensional changes in the widths of the said first 38a, second 38b and third 38c undercuts can be done. For example, widths of first 38a and second 38b can be equal. Respective similar dimensional changes can be done in the distal attachment end 40 profile of the plunger rod 14 for a secure fitment with the plunger top 12. It is to be understood that if the undercut widths on the plunger top 12 are modified, corresponding changes would also be made to the distal attachment end 40 profile of the plunger rod 14 ensuring a secure and compatible fitment between the plunger top and plunger rod components, regardless of the specific undercut dimensions used.

As shown in Fig. 1E and 1F, the plunger top 12 has a proximal face 44 wherein one or more projections 46 are provided so that the plunger top 12 once assembled on the plunger rod 14 does not stick to the plunger rod 14. In addition, said one or more projections 46 helps in enhancing the sealing of the plunger top 12 with the plunger rod 14. In some examples, the proximal face 46 of the plunger top 12 is provided with at least two projections 46. It is to be understood that the positioning of these projections may vary in that such projections 46 may be evenly spaced apart on the proximal face 44 or such projections 46 may be arranged in a non-uniform pattern. In some examples,

Further, as shown in Fig. 1C, 1E & 1F, the plunger top 12 comprises a width and a height. The width is having a diameter which is at least two times greater than the height of the plunger top 12 as seen in axial direction A which further helps in reducing friction forces. Thus, as described above, the plunger top 12 including a sealing portion 30a, 30b adapted to form a seal with the syringe 16 and a central conical tip portion 26 adapted to contact fluid within the syringe 16, allowing for precise fluid control and delivery. The large diameter provides a stable base for the plunger top 12 and helps distribute forces more evenly during use.

Referring to Figs. 2A and 2B, a new plunger body design is shown having a plunger rod 14. The plunger rod 14 is preferably made of a rigid plastic material including thermoplastic material. The plunger rod 14 has an elongated plunger rod body 54 portion having a proximal 24 and distal 22 end and a sidewall portion 56 extending along an axial direction A between the proximal 24 and distal 22 end. The sidewall portion 56 of the plunger rod 14 is provided with one or more longitudinally extending ribs 58 to provide additional strength as well as to make the plunger rod 14 lighter in configuration. The ribs 58 also improve the gliding features of the plunger rod 14 within the syringe barrel 18 during use.

The proximal end 24 of the plunger rod includes a base profile 48 in a circular shape which helps in pulling or pushing of the plunger rod 14 from or within the syringe barrel 18. It is to be understood that the shape of base profile 48 is not limited to circular shape only and may include any other shape such as oval, square or the like. Further, the base profile 48 at its proximal face has a plurality of projections creating a thumb press area 52 for application of force to the plunger rod 14 during use. In addition, closer to the distal end 22 of the plunger rod 14 a top profile 64 in a circular shape is provided. The top profile 64 is adjoined with the ribs 58. Both the top profile 64 and the base profile 48 serve provide strength to the ribs 58 and further improve the gliding features of the plunger rod 14 within the syringe barrel 18 during use.

The distal end 22 of the plunger rod 14 forms a front attachment end 40 with a specific locking profile 50 as shown in Fig. 3A. This locking profile 50 is designed to be fixedly received within the first 38a, second 38b and third 38c undercuts on the plunger top 12. The undercuts have a corresponding shape and configuration that perfectly matches the locking profile 50 on the plunger rod 14. This precise fit prevents any detachment of the plunger top 12 once it is assembled and/or fixedly received over the plunger rod 14.

The plunger rod 14 comprises longitudinal ribs 58 that define and interior hollow portion(s) between them. In some examples, the ribs 58 define the interior hollow portion(s) being in equidistant spaced apart arrangement in between the ribs 58 with respect to one another. However, in some examples the ribs 58 can be arranged without maintaining such equidistant spaced apart arrangement in between the ribs 58. It is to be understood that the specific shape and configuration of the plunger rod 14 provides sturdiness to the body portion 54 of the plunger rod 14 and has other advantages in terms of providing ease in use, reduction of production cost and easier manufacturing process and assembly.

The plunger rod 14 design having a length allows for flexibility in the number and arrangement of the longitudinal ribs 58. In the example shown, the number of ribs 58 is even numbers, however, in some examples, the number of ribs 58 may be in odd numbers, for example the plunger rod 14 may include three or five ribs 58 design. One or more notches 62 is/are provided on the ribs 58. These notches 62 help in reducing friction experienced by the plunger rod 14 during use within the syringe barrel 18. The location of such notches 62 as shown in the ribs 58, preferably, is in center of the rib length, on at least one of the ribs 58. However, in some examples, the number of notches 62 and its location on the ribs may be varied as per need. The entire plunger rod 14 preferably has a unitary structure. The single-piece design has advantages in terms of assembly, durability, and cost effectiveness. However, it is to be understood that the plunger rod 14 may alternatively be made up of one or more individual parts that are assembled together.

Reference is now made to FIG. 3A to 3C, which show a syringe 16 in accordance with some examples of the present disclosure. As shown, the syringe 16 comprises a plunger top 12 and a plunger rod 14 wherein the plunger top 12 and plunger rod 14 are adapted for use within a syringe barrel 18. The syringe 16 has a generally cylindrical body and is preferably of a type that is pre-filled and sterilized for use in flush applications. In some examples, it is to be understood that a non-filled syringe 16 may also be used. The syringe barrel 18 has a distal or front end 22, and an open proximal or rear end 24 for receiving the plunger top 12 and plunger rod 14 assembly, and a sidewall 32 with a diameter extending between the proximal 22 and distal end 24. As shown in Fig. 3A, the plunger top 12 contacts the fluid within the syringe 16 and forms a seal with the inner side wall 32 of the syringe barrel 18 to contain the fluid inside syringe 16. The distal end 22 includes and terminates into an outlet 74 and/or a mechanism for attachment of a separate medical device (such as a catheter) or a tip closure member shown in the form of a luer 20 or a luer cap. The opening outlet 74 has a second internal diameter that is less than the first internal diameter of the syringe barrel 18.

The syringe barrel 18 has an interior surface 70 that includes a slight taper 66 at a forward end closer to the distal or front end 22 thereof. The taper 66 is adapted for contacting a corresponding taper 68 formed in the conical tip 26 of the plunger top 12. When a forward force is applied to the plunger rod 14, the interaction between the tapered surfaces 66 and 68 applies a radial force to the plunger top 12. The slight taper 66 in the syringe barrel 18, not being limited to, has an angle of at least more than 0.1°. Such a precise taper angle, combined with the matching taper 68 on the plunger top 12 conical tip 26, creates an effective sealing interface. The radial force generated helps to maintain a tight seal between the plunger top 12 and the syringe barrel 18 during use, preventing leakage and ensuring accurate fluid control. In some examples, the slight taper 66 in the syringe barrel 18, not being limited to, may have an angle of at least more than 0.2°, 0.3°, 0.4°. These specific taper angle ranges have been carefully selected to optimize the performance of the syringe system. However, it is to be understood that the taper angle is not limited to only such specific angle and may vary. The tapered design of both the syringe barrel 18 and plunger top 12 facilitates in zero reflux by creating a positive displacement of fluid into any attached catheter after the plunger top 12 has been fully bottomed or depressed. During use the application of pressure and force on the plunger rod 14 advances the plunger top 12 into the syringe barrel 18 until the conical tip 26 portion contacts the interior surface 70 of the syringe barrel 18 forming a seal and trapping fluid from flowing into the luer 20 and any attached catheter. Instead, the tapered interface creates a positive displacement of the fluid, forcing it out through the outlet 74 and into the connected medical device. This zero reflux capability is one of the key advantages of the tapered barrel and plunger top design.

Thus, the improved design of the syringe 16, including the plunger top 12 and plunger rod 14 achieves significant performance benefits. Once the plunger rod 14 is fully depressed and bottomed within the syringe barrel 18, and the force on the plunger rod 14 is released, the system achieves positive displacement of the fluid. Moreover, the improved plunger top 12 with the conical tip 26 has a profile adapted to create a positive seal with the opening outlet at the front end 22 of the syringe barrel 18 wherein the plunger top 14 seats against the opening outlet 74 and seal the opening without any deformation of the conical tip 26 portion. The combination of the plunger top 12 conical tip 26 profile and the tapered interior 66 of the syringe barrel 18 ensures a secure, leak-proof seal. This seal traps the fluid inside the syringe and, upon release of the plunger rod 14, positively displaces the fluid out through the outlet 74 and into the connected medical device.

Although this disclosure has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the present disclosure extends beyond the specifically disclosed embodiments and/or examples to other alternative embodiments and/or examples and/or uses of the disclosure and obvious modifications and equivalents thereof. Thus, from the foregoing description, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the disclosure as set forth in the claims.

Accordingly, it is not intended that the scope of the foregoing description be limited to the exact description set forth above, but rather that such description be construed as encompassing such features that reside in the present disclosure, including all the features and embodiments and/or examples that would be treated as equivalents thereof by those skilled in the relevant art.

While aspects of the present disclosure have been described in detail with reference to the illustrated embodiments and/or examples, those skilled in the art will recognize that many modifications may be made thereto without departing from the scope of the present disclosure. The present disclosure is not limited to the precise construction and compositions disclosed herein; any and all modifications, changes, and variations apparent from the foregoing descriptions are within the spirit and scope of the disclosure as defined in the appended claims. Moreover, the present concepts expressly include any and all combinations and sub combinations of the preceding elements and features. The description is provided for clarification purposes and is not limiting. Words and phrases are to be accorded their ordinary, plain meaning unless indicated otherwise.

The scope of the present disclosure herein disclosed is not limited by the particular disclosed embodiments and/or examples described above but determined only by a fair reading of the appended claims. All changes and variations that fall within the meaning and range of equivalency of the claims are to be embraced within their scope.
List of reference numerals:

10 plunger
12 plunger top,
12a main body
14 plunger rod
16 syringe
18 syringe barrel
20 tip closure member/luer member
22 distal end or front end
24 proximal end or rear end
26 conical tip/conical tip portion
28 outer surface area of the conical tip
30a sealing ring/sealing portion
30b sealing ring/sealing portion
32 inner wall of the syringe barrel
34a curved profile
34b curved profile
36 arch area or a change in profile area
38a first undercut
38b second undercut
38c third undercut
40 tip end or distal end or front attachment end of plunger rod
42 walls of third undercut
44 proximal face
46 projection(s)
48 base profile
50 locking profile
52 thumb press area
54 plunger rod body/portion
56 sidewall portion
58 ribs
60 interior hollow ribs
62 notch
64 top profile
66 taper
68 corresponding taper
70 interior surface
72 sidewall of syringe barrel
74 opening outlet
76 tip end of conical tip
A axial direction
,CLAIMS:WE CLAIM:

1. A plunger (10) comprising a plunger top (12) adapted for attachment with a plunger rod (14) for use within a syringe barrel (18) of a syringe (16), said plunger top (12) comprising:
a main body (12a) defining an open proximal or rear end (24) and a closed distal or front end (22);
at least two sealing rings (30a, 30b) forming an outer contact and sealing area with an inner wall (32) of the syringe barrel (18) when the plunger top (12) is slidably arranged within the syringe barrel (18) of the syringe (16);
at least one arch area or a change in profile area (36) in between the two-sealing ring(s) (30a, 30b); wherein the plunger top (12) is configured to create a positive seal with the syringe barrel (18) and to prevent fluid reflux during use.

2. The plunger (10) as claimed in claim 1, wherein the closed distal or front end (22) forms a conical tip (26), wherein the conical tip (26) is defined by an inner and an outer angle(s).

3. The plunger (10) as claimed in claim 2, wherein the inner angle(s) forming the conical tip (26) of the plunger top (12) is at least more than 90°, and the conical tip (26) has rounded edges.

4. The plunger (10) as claimed in claim 2, wherein the outer angle(s) forming the conical tip (26) of the plunger top (12) is at least more than 10°.

5. The plunger (10) as claimed in any one of claims 1 to 4, wherein a combination of the inner and outer angle(s) of the conical tip (26) creates an outer surface area (28).

6. The plunger (10) as claimed in any one of claims 1 to 5, wherein the conical tip (26) of the plunger top (12) includes a tip end (76) that is substantially centered within the conical tip (26), the outer surface area (28) of the conical tip (26) portion includes a sloped outer surface extending from a distal end of the first sealing ring (30a) to the tip end (76) of the conical tip (26), the sloped outer surface of the conical tip (26) facilitating zero reflux and minimizes the dead space within the syringe (16) during use.

7. The plunger (10) as claimed in claim 1, wherein a proximal end part of the second sealing ring (30b) has a curved profile (34b) .

8. The plunger (10) as claimed in claim 1, wherein the arch area or change in profile area (36) of the plunger top (12) has a slightly curved profile (34a); the change in profile area (36) is compressed in form, creating less contact area with the inner wall (32) of the syringe barrel (18).

9. The plunger (10) as claimed in claim 1, wherein the plunger top (12) has a first undercut (38a) profile; the first undercut profile (38a) is located proximal to and underneath the conical tip (26).

10. The plunger (10) as claimed in any one of claims 1 to 9, wherein the plunger top (12) further comprises a second undercut (38b) located proximal to and underneath the first undercut (38a); and a third undercut (38c) located proximal to and underneath the second undercut (38b).

11. The plunger (10) as claimed in any one of claims 1 to 10, wherein the third undercut (38c) has an inner periphery defined by walls (42); the walls (42) have an angled profile for smooth assembly of the plunger top (12) with the plunger rod (14).

12. The plunger (10) as claimed in any one of claims 1 to 11, wherein the plunger rod (14) has a tip end (40) forming a lock feature; the lock feature at the tip end (40) is fixedly received within the first undercut (38a) of the plunger top (12).

13. The plunger (10) as claimed in any one of claims 1 to 12, wherein each of the first 38a, second 38b and third 38c has a specific width dimension; wherein width of the first undercut (38a) is greater than the widths of the second (38b) and third (38c).

14. The plunger (10) as claimed in claim 1, wherein the plunger top (12) has a proximal face (44); the proximal face (44) of the plunger top (12) has one or more projections (46).

15. The plunger (10) as claimed in claim 1, wherein the plunger top (12) comprises a width and a height, wherein the width having a diameter which is at least two times greater than the height of the plunger top (12) as seen in axial direction (A).

16. The plunger (10) as claimed in claim 1, wherein the main body (12a) of the plunger top (12) has a unitary structure.

17. The plunger (10) as claimed in claim 1, wherein the main body (12a) of the plunger top (12) fabricated in parts or having one or more parts.

18. The plunger (10) as claimed in claim 1, wherein the plunger top (12) is made of an elastomeric material selected from the group of thermoplastic elastomers, non-porous rubber material, natural rubber, synthetic rubber, thermoplastic vulcanizates (TPV) and/or combinations thereof.

19. The plunger (10) as claimed in claim 1, wherein the plunger rod (14) has an elongated plunger rod body (54) portion with a proximal (24) and a distal (22) end and a sidewall portion (56) extending along an axial direction (A) between the proximal (24) and distal (22) end.

20. The plunger (10) as claimed in claim 19, wherein the sidewall portion (56) of the plunger rod (14) provided with one or more longitudinally extending ribs (58).

21. The plunger (10) as claimed in claim 19, wherein the distal end (22) of the plunger rod (14) forms a front attachment end (40); the front attachment end (40) has a locking profile (50); the locking profile (50) is fixedly received within the first (38a), second (38b) and third (38c) undercuts; the first, second and third undercuts have corresponding shapes and configurations that match the locking profile (50).

22. The plunger (10) as claimed in claim 1, wherein the syringe barrel (18) comprising a distal or front end (22), an open proximal or rear end (24) for receiving the plunger top (12) and plunger rod (14) assembly and a sidewall (72) having a first internal diameter extending between the proximal (22) and distal end (24).

23. The plunger (10) as claimed in claim 22, wherein the distal end (22) including an opening outlet (74) and/or a mechanism for attachment of a separate medical device or a tip closure member (20) and wherein the opening outlet (74) has a second internal diameter which is less than the first internal diameter.

24. The plunger (10) as claimed in any one of claims 1 to 23, wherein the syringe barrel (18) includes an interior surface (70) having a slight taper (66) at a forward end closer to the distal or front end (22) thereof adapted for contacting a corresponding taper (68) formed in the conical tip (26) of the plunger top (12).

25. The plunger (10) as claimed in claim 24, wherein the slight taper (66) in the syringe barrel (18) has an angle of at least more than 0.1 degree.