# Patent

## Title
Quick release plunger

## Abstract

A stopper configured to slidably move within the hollow lumen of a syringe to facilitate movement of fluid within the syringe. The stopper includes a base and one or more capture members extending rearwardly from the base. The one or more capture members each include a beveled edge configured to interact with a piston of a fluid injection apparatus, wherein the one or more capture members are radially deflected upon rotation of the stopper relative to the piston to facilitate removal of the stopper from the piston. The stopper is configured for slidable movement within a body of a syringe and forms a fluid tight seal with an inner wall of the body of the syringe. Also disclosed is a plunger which includes the stopper.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a Continuation of U.S. application Ser. No. 13/792,155, filed Mar. 10, 2013, issued as U.S. Pat. No. 9,174,003, and claims the benefit of U.S. Provisional Patent Application No. 61/707,690, filed Sep. 28, 2012, and entitled “QUICK RELEASE PLUNGER” and of U.S. Provisional Patent Application No. 61/710,570, filed Oct. 5, 2012, and entitled “QUICK RELEASE PLUNGER,” the entire contents of which are hereby incorporated by reference.


BACKGROUND
A number of injector-actuated syringes and powered injectors have been developed for use in medical procedures, such as, for example, angiography, computed tomography, and nuclear magnetic resonance. Numerous advances have been made in the area of injector-actuated syringes and power injectors for use therewith. Nonetheless, newly developed and developing medical procedures constantly test the limits of current injector systems. For example, some procedures require the use of high pressures but also require physiochemical properties of the syringe that make attainment of high pressures difficult. Changes in syringes to meet the requirements of the newly developed and developing medical procedures may result in necessary changes to other portions of the injector to properly operate with the syringe, which puts care providers at the disadvantage of having to obtain new and costly injectors each time a new syringe is developed.
SUMMARY
In an embodiment, a syringe system may include a syringe body having a hollow lumen, a proximal open end, and a distal end. The syringe body may be configured to house a fluid therein. The syringe system may further include a plunger positioned in the hollow lumen of the syringe body, forming a seal with an inner wall of the syringe body. The plunger may include a removable piston having a shaft extending from the distal end towards the proximal open end, a stopper removably connected to a distal portion of the shaft, and at least one coupler attached to the distal portion of the shaft. The stopper may be configured to slidably move within the hollow lumen to facilitate movement of the fluid within the syringe body. The coupler may be configured to facilitate removal and attachment of the stopper from the piston.
In an embodiment, a plunger apparatus that can be at least partially removed from a syringe may include a removable piston having a shaft extending from a distal end of the syringe towards a proximal open end of the syringe, a stopper removably connected to a distal portion of the shaft, and at least one coupler attached to the distal portion of the shaft. The stopper may be configured to slidably move within a hollow lumen of the syringe to facilitate movement of fluid within the syringe. The coupler may be configured to facilitate removal and attachment of the stopper from the piston.
In an embodiment, hydraulically-activated plunger in a fluid delivery system may include a first syringe comprising a first diameter, a proximal end, a distal end having an aperture, and a hollow lumen configured to house a fluid therein, and a stopper configured to slidably move within the hollow lumen to facilitate movement of the fluid within the hollow lumen, an internal piston having a distal end and a proximal end. The distal end may be removably attached to the stopper and configured to move the stopper within the hollow lumen of the first syringe, and the proximal end may be fluidly attached to a second syringe having a proximally positioned tip and a second diameter that is smaller than the first diameter. The plunger may further include a third syringe having a distally positioned tip and a third diameter that is smaller than the first diameter, wherein the distally positioned tip of the third syringe is in fluid communication with the proximally positioned tip of the second syringe and an external piston fluidly connected to the third syringe. The external piston may include a plunger and the second syringe and the third syringe may each contain an incompressible fluid sealed therein.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a side view of a syringe according to an embodiment.
FIG. 2 depicts a stopper according to an embodiment.
FIG. 3 depicts a piston according to an embodiment.
FIG. 4A depicts a piston having a separable coupler according to an embodiment.
FIG. 4B depicts a cross-sectional top view and bottom view of a coupler according to an embodiment.
FIG. 4C depicts a cross-sectional top view and bottom view of an alternate coupler according to an embodiment.
FIG. 4D depicts a separable coupler according to an embodiment.
FIG. 5 depicts a side view of various parts of a clamping mechanism according to an embodiment.
FIG. 6A depicts a clamping mechanism engaged with a piston according to an embodiment.
FIG. 6B depicts a piston disengaged from a clamping mechanism according to an embodiment.
FIG. 6C depicts a piston disengaged from a clamping mechanism according to an embodiment
FIG. 7A depicts a piston disengaged from a clamping mechanism according to an embodiment.
FIG. 7B depicts a piston engaged with a clamping mechanism according to an embodiment.
FIG. 8 depicts a piston having an angled end according to an embodiment.
FIG. 9 depicts a piston having multiple, detachable couplers according to an embodiment.
FIG. 10 depicts a piston having a hydraulic assist according to an embodiment.
FIG. 11 depicts a piston having a volume measuring scale according to an embodiment.



DETAILED DESCRIPTION
This disclosure is not limited to the particular systems, devices and methods described, as these may vary. The terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope.
As used in this document, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Nothing in this disclosure is to be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior invention. As used in this document, the term “comprising” means “including, but not limited to.”
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 orientation of embodiments disclosed in the figures. However, embodiments may assume alternative variations and step sequences, except where expressly specified to the contrary. The specific devices and processes illustrated in the attached drawings and described in the following specification, are exemplary embodiments. Hence, physical characteristics related to the embodiments disclosed herein are not to be considered as limiting.
The word “proximal” refers to a direction relatively closer to a clinician or operator using the device described herein, and the word “distal” refers to a direction relatively further from the clinician or operator. For example, the end of a syringe placed nearest the body of a patient is considered a distal end of the syringe, while the end closes to the clinician is a proximal end of the syringe. The terms “axial” or “axially” refer generally to an axis around which the particular objects being referred to are preferably formed (although not necessarily symmetrically therearound). The term “radial” refers generally to a direction normal to the axis or along a radius of an object having a circular cross-section.
Various embodiments are directed to plungers for syringes, including stoppers that may be connected and disconnected from the piston. In various embodiments, such plungers may be manually, hydraulically, or electrically activated. In the embodiments disclosed herein, the same injector can be used for a variety of different syringes because of the ease of attaching and removing the piston portion of the syringe to the stopper portion through the use of a coupler. Furthermore, the present disclosure provides a quick and easy solution for care providers because the piston can be inserted and connected to the stopper without a specific orientation. For example, a user may advance the piston forward until it engages with the connector by snapping into place, regardless of orientation, as will be described in greater detail herein. In addition, a simple 1⁄4 turn twist at any orientation may allow for detachment of the two elements.
FIG. 1 depicts a syringe, generally designated 10, that may include a cylindrical syringe body 1 defining a hollow lumen 4 therein, an open proximal end 3, and a conical shaped distal end 2 having an aperture 5. A plunger, generally designated 12, may be positioned in the hollow lumen 4 of the syringe body 1 extending from the conical shaped distal end 2 and towards the open proximal end 3. The plunger 12 may include a piston 100 having a shaft 115 extending from a proximal thumb rest 110 to a distal stopper 20. In various embodiments, an attachment may be attached to the distal end 2 of the syringe 10 to facilitate delivery and/or movement of the fluid of the syringe body 1 to or from, for example, a blood vessel and/or the like of a human or an animal patient. Specific examples of attachments may include, for example, needles, catheters, tubes, and/or the like.
The stopper 20 may generally have a circumference that is substantially equal to an inner circumference of the syringe body 1 and may be received by the open proximal end 3 of the syringe body. The stopper 20 may slidably move within the lumen 4 to facilitate movement of fluid within the syringe body 1. The type of fluid is not limited by this disclosure and may include any fluids including, for example, a pharmaceutical drug, a radiopharmaceutical, a contrast agent, a radioactive contrast agent, gene therapy fluid, and/or the like. In some embodiments, the stopper 20 may facilitate movement of the fluid towards and through the distal end 2 of the syringe 10. In other embodiments, the stopper 20 may facilitate movement of the fluid towards the proximal end 3 of the syringe 10. In particular embodiments, as shown in FIG. 2, the stopper 20 may have a cylindrical body 22 and a protrusion tip 21 sized and configured to substantially fill at least a portion of the conical shaped distal end 2 of the syringe body 1 (FIG. 1).
Referring back to FIG. 1, the piston 100 may provide a generally reciprocal movement of the stopper 20 through the syringe body 1. In some embodiments, movement of the stopper 20 and/or the piston 100 may allow for the fluid to be drawn into the lumen 4 of the syringe body 1 by placing the distal end 2 of the syringe body and/or an attachment thereto into the fluid and withdrawing the plunger 12. In some embodiments, movement of the stopper 20 and/or the piston 100 may allow for the fluid to be expelled from the lumen 4 of the syringe body 1 by advancing the piston into the syringe body. In some embodiments, the stopper 20 may be fixedly attached to a proximal end 105 of the piston 100. In other embodiments, the stopper 20 may be detachably connected to the proximal end 105 of the piston 100, allowing the piston to be removed and used with one or more different components discussed herein, such as stoppers and the like. For example, in the case of pre-filled syringes, various components may be reused to reduce the amount of disposable materials.
As depicted in FIG. 3, the plunger 12 configured according to some embodiments may include, for example, a piston 100 having a proximal end 107 and a distal end 105. The proximal end 107 may include at least a thumb rest 110 that may be configured to be used by an operator to move the plunger 12 axially forward or backward within the syringe body 1 (FIG. 1). In some embodiments, a coupler 150 may be attached to the distal end 105 of a piston 100. Referring also to FIG. 4A, in some embodiments, a proximal end 135 of the coupler 150 may be detachably connected to a shaft 115 of the piston 100 using a fastening mechanism such as, for example, screws, snaps, rivets, and/or the like, as will be described in greater detail herein. In other embodiments, the coupler 150 may be fixedly attached to the shaft 115 using, for example, an adhesive. In still other embodiments, the coupler 150 may be a contiguous part of the piston 100 by, for example, injection molding the piston to include the coupler.
In various embodiments, the coupler 150 may include a substantially circumferential groove 140 (or 140′ in FIG. 4C) at a distal end 130 of the piston 100. In some embodiments, the groove 140 (or 140′) may be continuous for the entire length of the coupler 150. In other embodiments, the circumferential groove 140 (or 140′) may contain one or more gaps therein. In some embodiments, the groove 140 (or 140′) may have at one or more extensions (element 147 in FIG. 4B or 147′ in FIG. 4C)) extending radially from the groove. In particular embodiments, the groove 140 may include about 1 to about 8 extensions. In other particular embodiments, the groove 140 may include 2 extensions, 3 extensions, 4 extensions, 5 extensions, 6 extensions, or 8 extensions. The extensions 147 (or 147′) may extend outwardly from the groove 140 (or 140′) at least to an outer circumference of the piston 100. In some embodiments, the extensions 147 (or 147′) may extend beyond the outer circumference of the piston 100. The extensions 147 (or 147′) may have a substantially triangular shape, such as, for example, a substantially equilateral triangle, a substantially isosceles triangle, a right triangle, and the like. In some embodiments, the extensions 147 may include at least one or more notches 155 on one or more sides of the extensions on an outermost portion of each extension. The notches 155 may have any cross-sectional shape such as, for example, a square (as shown in FIG. 4B), a rectangle, a triangle, a circle, an ellipse, and/or the like. In various embodiments, the notches 155 may or may not be symmetrical. In some embodiments, the extensions 147 and the notches 155 may intersect in a flat 170 (FIG. 4A) such that the flat is substantially tangential to the outer surface of the extension.
In some embodiments, as illustrated in FIG. 4D, the notches 155′ may extend from the surface of the extension 147′. The notches 155′ may have, for example, a triangular cross-section having straight and/or curved sides, or any other shape (not shown). In some embodiments, the notches 155′ may or may not be symmetrical. In various embodiments, an outermost edge of the notches 155′ may extend beyond the outermost circumference of a tapered flange 145′. In some embodiments, the notches 155′ may be angled to extend from the proximal end of the extensions 147′ distally towards the tapered flange 145′ forming a helical ridge. In some embodiments, the notches 155′ may be tapered distally along the circumferential surface of the extensions 147′. Various embodiments may have one or more notches 155′, such as, for example, two notches.
In some embodiments, the coupler 150 may include the tapered flange (145 in FIG. 3 or 145′ in FIG. 4C) extending distally from the groove 140 (or 140′). In some embodiments, a maximum radius of the tapered flange 145 (or 145′) may be equal to or shorter than the radius of the piston 100. In some embodiments, one or more deflectors 157 (FIG. 4A) may be disposed as one or more protuberances on the outer surface of the tapered flange 145 and may be axially distal to the notches 155. The shape of the deflectors is not limited by this disclosure, and may include any shape. Specific examples of deflector shapes may include conical shapes, hemispherical shapes, triangular shapes, and/or the like.
In various embodiments, the proximal end of the piston 100 may be detachably connected to one or more actuating mechanisms (not shown) such as, for example, a hydraulic assembly and/or an electric motor to aid the motion of the piston.
Referring to FIGS. 5 and 6A-6C, the distal portion of the piston 100 and/or the coupler 150 may be configured to engage the stopper 20 (FIG. 1) as described herein. In some embodiments, the stopper 20 (FIG. 1) may include at least a base 200 including one or more capture members 220 protruding rearwardly beyond the rear surface 255 of the base by an amount sufficient to capture and retain the tapered flange 145 of the coupler 150. The capture members 220 may be constructed of a flexible material such that the capture members flex outwardly when contacted by the tapered flange 145 and subsequently snap back to an original position after passing the tapered flange to engage the circumferential groove 140. While embodiments having two capture members 220 are shown and described here, embodiments having more than two capture members are also envisioned, depending on, among other things, the shape of the coupler and/or the number of extensions 147. The capture members 220 may include inwardly facing shoulders 215 that may be sized and designed to engage the circumferential groove 140 extending from each capture member on a proximal end of the capture member. In certain embodiments, the capture members 220 may further include extensions 225 extending proximally beyond the inwardly facing shoulders 215. In various embodiments, the base 200 may or may not be detachable from the stopper 20 (FIG. 1). In embodiments where the base 200 is detachable from the stopper 20, the base may have one or more helical threads 260 at its distal end 270 that may be configured to be screwed into an opening in the proximal end 25 of the stopper (FIG. 1).
As shown in FIG. 6A, in operation, the piston 100 may be positioned to contact the base 200 and engage the tapered flange 145. As the piston 100 is pushed against the base 200, the inwardly facing shoulders 215 may be forced outwardly until the tapered flange 145 passes beyond the shoulders of the capture members 220, as described in greater detail herein. This design may allow the piston 100 to stably engage with the stopper 20 (FIG. 1) at any axial position of the plunger 12 along the syringe axis without substantially dislocating the stopper from its position along the syringe axis. In some embodiments, the shoulders 215 may be aligned to engage the circumferential groove 140 when the stopper 20 (FIG. 1) is properly mounted in the syringe body 1. In some embodiments where the circumferential groove 140 contains one or more gaps as described herein, the gaps may allow the shoulders 215 to release up with a deflector to prevent the shoulders from being loaded in the gap. In embodiments having deflectors disposed on the tapered flange 145 as previously described herein, the deflectors may deflect the capture members 220 to prevent the capture members from lining up with the notches 155.
After retention of the coupler 150 (FIG. 3) by the capture members 220, the stopper 20 may resist disconnection from the piston 100 upon rearward movement of the piston. In some embodiments, the capture members 220 may be designed such that forces exerted on the capture members upon rearward movement of the piston 100 substantially prevent radially outward movement of the capture members. In some embodiments, shoulders 215 of the capture members 220 may be positioned such that the load experienced upon rearward movement of the piston 100 is at a position equal to or greater in radial distance relative to axis B than one or more anchors 250 where the capture members are attached to the base 200. Thus, a bending movement created by a rearward movement of the piston 100 may cause the capture members 220 to deflect radially inward and assist in preventing disconnection of the stopper 20 (FIG. 1) from the piston 100.
When the piston 100 is twisted about its axis B, the extensions 147 (or 147′) may push the capture members 220 radially outward as the radial distance of the groove 140 surface increases allowing the piston to be disengaged from the stopper 20 upon rearward movement of the piston while it is twisted. In embodiments having notches 155 extending from the extensions 147, the notches may act as position indicators and/or twist-stops to stop the piston 100 from further twisting. In some embodiments, the flats 170 may provide positions at which the piston 100 may be disengaged from the stopper 20 (FIG. 1). This design may allow for detachment of the piston 100 from the stopper 20 with a twist of the piston that depends on the number of extensions 147 or the number of capture members 220. In particular embodiments, the twist of the piston 100 may be less than 180°, less than 120°, less than 90°, less than 72°, less than 60°, or less than 45°.
In embodiments such as those depicted in FIGS. 4D and 6C, the piston 100 may be twisted about its axis B in such a manner that the notches 155′ extending from the extensions 147′ may push the beveled edges 210 (FIG. 5) of the capture members 220. In some embodiments, the beveled edges 210 (FIG. 5) may be pushed axially forward in a direction forward of the outer circumference of the tapered flange 145′. In some embodiments, the beveled edges 210 (FIG. 5) may be pushed such that the inwardly facing shoulders 215 of the base 200 are disengaged from the tapered flange 145′. This movement may disconnect the stopper 20 (FIG. 1) from the piston 100 when the stopper 20 is connected to the base 200. Additionally, in embodiments in which the notches 155′ are formed as distally angled helical ridges on the extension 147′ surface, twisting the piston 100 may result in pushing the beveled edges 210 radially outward by the extension surface and axially forward by the notches. As such, the inwardly facing shoulders 215 of the capture members 220 may clear the tapered flange 145′ while the piston 100 is being twisted. In embodiments where a user attempts to attach the piston 100 in an orientation where the notches 155 extending from the extension 147′ line up with the beveled edges 210, the one or more deflectors 157 (FIG. 4A) may push the beveled edges to either side of the deflector so that the beveled edges do not get stuck in the notches.
In various embodiments, as depicted in FIGS. 7A and 7B, one or more cantilevered capture members 320 may be disposed at the distal end of the piston 300 anchored from the distal wall 310 of the piston and disposed around a central extension 340 of the piston. In such embodiments, the capture members may have outwardly extending shoulders 325 and beveled surfaces 327 at the distal end of the capture members 320. In some embodiments, the piston 300 may have at least two capture members 320. In some embodiments, the piston 300 may have 2, 3, 4, 5, 6, or 8 capture members 320. In some embodiments, the piston 300 may have capture members 320 that may be symmetrically disposed around the central extension 340.
In various embodiments, the stopper 350 may have one or more retainer arms 360. In other embodiments, a base (not shown) having retainer arms 360 may be fabricated to fit into a stopper 20 for retrofitting one or more commercially available stoppers. As the piston 300 is moved forward through an opening 355 provided by the retainer arms 360 of in the stopper 350, the beveled surfaces 327 may tend to push the capture members 320 radially inward. Upon passing the retainer arms 360 of the stopper 350, the capture members 320 may snap back to engage the shoulders 325, thereby preventing the piston 300 from detaching from the stopper upon rearward movement of the piston. In various embodiments, the capture members 320 may be placed around the piston head 340 such that a rearward movement of the piston 300 pushes the capture members radially outward.
As depicted in FIG. 8, some embodiments may include a piston 500 having a coupler that is an angled flange 510 contiguously connected to the piston 500 via a hinge 525 such that a distal surface 535 of the angled flange may form an angle θ, with the axis D of piston 500. In particular embodiments, the angle θ may be acute. In some embodiments, the hinge 525 may have an open position wherein the radially outermost portion of the distal surface 535 of the angled flange 510 extends no further than the outer wall 530 of the piston 500. In some embodiments, the hinge 525 of the angled flange 510 may have a closed position wherein the angled flange 510 tilts about the hinge at an increased angle θ.
In some embodiments, the plunger 12 may be operated by moving the piston 100 forward and twisting it. The angled flange 510 may engage with one or more threads 555 disposed on an inner wall of the stopper 550. Upon further forward movement, the angled flange 510 may tilt about the hinge 525, thereby placing the hinge in the closed position, and further engaging with the threads 555. This may prevent the piston 500 from detaching from the stopper 550 when moved in a rearward direction. Likewise, twisting in an opposite direction may disengage the angled flange 510 from the threads 555, thereby placing the hinge in the open position and allowing the piston 500 to be detached from the stopper 550. Such a design may allow for an easy engagement and/or detachment of the piston 500 from the stopper 550 in, for example, pre-filled syringes. Such a design may also allow for an easy engagement and/or detachment of any axial position of the stopper 550 without substantially dislocating the stopper from its axial position.
As depicted in FIG. 9, some embodiments of the piston 400 may include a plurality of axially-stacked detachable couplers 410, 410A, 410B. In various embodiments, the plurality of couplers 410, 410A, 410B may be stacked on a spring loaded platform 420 in an axially disposed cavity 430 within the piston 400. Retainer arms 425 at the opening of the cavity 430 may prevent the end coupler 410 from receding back into the cavity 430. When using the piston 400, the end coupler 410 may be removed or detached from the piston after using the piston with a first syringe. Another coupler 410A (or 410B) may replace the removed end coupler 410 and become the new end coupler for using the piston 400 with a second (or a subsequent) syringe. In various embodiments, the end coupler 410 may be removed by any means of removal now known or later developed, such as, for example, twisting the piston 400, detaching the piston using the various quick-release mechanisms described herein, or breaking the end coupler off. In some embodiments, any number of couplers 410 may be loaded inside the cavity 430 for use, where the number of piston heads is only limited by the size of the cavity and/or the storage capability of the cavity. A specific number of piston heads may be, for example about 1 piston head to about 10 piston heads. In some embodiments, the detachable coupler 410 may reduce cross-contamination, such as, for instance, when a single piston 400 is used with multiple syringes, where one of the detachable couplers may be removed and disposed of after each use.
In some embodiments, the piston may be part of a hydraulically activated or an electrically activated assembly. In some embodiments, for example, as depicted in FIG. 10, an internal piston 620 may have a hydraulic assist so as to reduce the force required by an operator using the syringe assembly 600 to deliver the contents of the syringe. A first syringe 605 portion of the syringe assembly 600 may have a diameter D3. The internal piston 620 may be connected to both the first syringe 605 and a second syringe 625 having a diameter D2. The diameter D2 of the second syringe 625 may generally be smaller than the diameter D3 of the first syringe 605. In some embodiments, the internal piston 620 may be connected to the first syringe 605 in such a manner that a proximal end 615 of the internal piston engages a first stopper 610 located in the first syringe. In some embodiments, the internal piston 620 may be connected to the second syringe 625 in such a manner that a distal end 617 of the piston engages a second stopper 630 located in the second syringe. A first tip 631 of the second syringe 625 may be connected to a second tip 632 of a third syringe 635. The third syringe 635 may have a diameter D1 that may be generally smaller than the diameter D2 of the second syringe 625.
In some embodiments, a lumen of the second syringe 625 and a lumen of the third syringe 635 may each be filled with an incompressible fluid 675. In particular embodiments, the incompressible fluid 675 may be sealed within the respective lumens of the second syringe 625 and the third syringe 635. An external piston 650 connected to the third syringe 635 may engage a plunger 640. When the external piston 650 is moved forward, the fluid 675 pushes the internal piston 620 which further pushes the first stopper 610. In some embodiments, because the fluid 675 is incompressible, the force placed upon the internal piston 620 is amplified by a factor of (D2)2/(D1)2 as the external piston 650 is moved forward. The diameters of various syringes 605, 625, 635 may be optimized by a skilled artisan depending on particular requirements for particular embodiments and/or usage thereof.
In any of the various embodiments disclosed herein, it may be desirable to determine the total volume delivered using a plurality of syringes. Pistons of some embodiments may have a sliding scale or a marker system for indicating and/or measuring the volume of fluid disposed out of or collected into the syringe before the piston is detached. For example, as illustrated in FIG. 11, a piston 725 may have at least a measuring scale 730 configured to indicate a volume displaced by the plunger 710 after the piston 725 is engaged with the plunger and moved forward through the syringe 700. In some embodiments, the scale 730 may be detachably affixed to an O-ring 750 such that the O-ring detaches from the scale when piston 725 engages with the plunger 710 and attaches to the piston marking an initial volume. As the piston 725 is moved forward through the syringe 700, the scale 730 may slide along the O-ring 750, thus indicating the volume being delivered or removed. A user of the syringe 700 may determine the volume of a particular fluid delivered or removed by observing the scale 730 marked on the syringe. The O-ring 750 may indicate a total volume delivered at the end of delivery by the syringe 700, including the volume delivered from other syringes.
Although various embodiments have been described in detail for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that the disclosure is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements. For example, it is to be understood that this disclosure contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.

## Claims

1. A stopper configured to slidably move within a hollow lumen of a syringe to facilitate movement of fluid within the syringe, the stopper comprising:
a base; and
one or more capture members extending rearwardly from the base, the one or more capture members each comprising a beveled edge,
wherein the beveled edge is configured to interact with a piston of a fluid injection apparatus and wherein the one or more capture members are radially deflected upon rotation of the stopper relative to the piston to facilitate removal of the stopper from the piston, and
wherein the stopper is configured for slidable movement within a body of a syringe and to form a fluid tight seal with an inner wall of the body of the syringe.

2. The stopper according to claim 1, wherein each of the one or more capture members comprise an inwardly facing shoulder.

3. The stopper according to claim 2, wherein the one or more capture members extend rearwardly from the base by an amount sufficient to releasably capture and retain a tapered flange on a coupler attached to the piston.

4. The stopper according to claim 3, wherein upon rotation of the stopper relative to the piston, the beveled edge is configured to be pushed radially outward such that the inwardly facing shoulders of the one or more capture members are disengaged from the tapered flange.

5. The stopper according to claim 3, wherein the inwardly facing shoulder of each of the one or more capture members is configured to engage a circumferential groove proximal to the tapered flange on the piston.

6. The stopper according to claim 5, wherein the one or more capture members may further comprise one or more extensions which extend proximally from the inwardly facing shoulder.

7. The stopper according to claim 5, wherein the one or more capture members are formed from a flexible material such that the one or more capture members flex radially outward when contacted by a taper of the tapered flange and subsequently snap back to an original position after passing the tapered flange to engage the circumferential groove.

8. The stopper according to claim 5, wherein the stopper is configured to resist disconnection from the piston upon rearward movement of the piston.

9. The stopper according to claim 5, wherein the one or more capture members are designed such that forces exerted on the one or more capture members upon a rearward movement of the piston substantially prevents radially outward movement of the one or more capture members.

10. The stopper according to claim 9, wherein a bending movement created by the rearward movement of the piston causes the one or more capture members to deflect radially inward.

11. The stopper according to claim 1, wherein the base is detachable from the stopper.

12. The stopper according to claim 1, wherein the stopper comprises a cylindrical body and is configured to substantially fill at least a portion of a conical shaped distal end of the syringe.

13. A plunger apparatus comprising:
a stopper configured to slidably move within a hollow lumen of a syringe to facilitate movement of fluid within the syringe, the stopper comprising:
a base; and
one or more capture members extending rearwardly from the base, the one or more capture members each comprising a beveled edge and an inwardly facing shoulder,
wherein the beveled edge is configured to interact with a piston of a fluid injection apparatus and wherein the one or more capture members are radially deflected upon rotation of the stopper relative to the piston to facilitate removal of the stopper from the piston.

14. The plunger apparatus of claim 13, further comprising a coupler for connection to a distal portion of the piston, wherein the coupler comprises a substantially circumferential groove having a plurality of extensions extending radially from the circumferential groove, wherein the extensions are configured to facilitate removable attachment of the stopper to the piston and wherein the inwardly facing shoulder of the one or more capture members are configured for engaging the circumferential groove.

15. The plunger apparatus of claim 14, wherein the coupler is fixedly attached to the distal portion of the piston.

16. The plunger apparatus of claim 14, wherein each of the plurality of extensions includes one or more notches on one or more sides of each extension on an outermost portion of each extension, wherein each of the one or more notches has a cross-sectional shape that is square, rectangular, triangular, circular, or elliptical.

17. The plunger apparatus of claim 14, wherein the coupler comprises a tapered flange extending distally from the circumferential groove, wherein the tapered flange is configured to removably secure the coupler to the stopper by locking with one or more capture members located on the stopper.

18. The plunger apparatus of claim 17, wherein the one or more capture members is constructed of a flexible material such that the one or more capture members flex outwardly when contacted by the tapered flange and subsequently snap back to an original position after passing the tapered flange to engage the circumferential groove.

19. The plunger apparatus of claim 17, wherein the one or more capture members protrude rearwardly beyond a rear surface of the base by an amount sufficient to capture and retain the tapered flange to effectively resist disconnection of the stopper from the piston.

20. The plunger apparatus of claim 19, wherein the one or more capture members may be configured to move radially outward from the base as a radial distance of the circumferential groove increases when the piston is rotated about an axis, allowing the piston to be detached from the stopper.