Syringe with bidirectional plunger advancement mechanism for microdosing syringe pumps

Abstract

A syringe for a microdosing syringe pump is disclosed. The syringe includes a reservoir having an outlet port, a plunger having a track, the plunger received within a portion of the reservoir, and a plunger drive mechanism including a gear connected to one end of a shaft and a pin disposed adjacent the other end of the shaft, the plunger drive mechanism being received within the plunger and the pin disposed within and engaging the track. In use, rotation of the gear in a first direction advances the plunger a first distance into the reservoir as the pin moves within the track, and rotation of the gear in a second direction opposite the first direction advances the plunger a further distance into the reservoir as the pin moves within the track. This design prevents overdosing in the event of a runaway failure of the motor.

Description

[Technical Field]

[0001] Disclosure Areas The present disclosure relates generally to syringes for microdosing syringe pumps, and more particularly to syringes having a bi-directional advancement mechanism and a runaway pump motor safety feature. [Background technology]

[0002] Background to the disclosure This section provides background information, not necessarily prior art, to inventive concepts related to the present disclosure.

[0003] Microdosing syringe pumps are known in the art and are often used to deliver medications such as insulin, other hormones, chemotherapy drugs, antibiotics, and painkillers, to name a few. These devices generally include a syringe with a reservoir, a plunger, and a means for driving the plunger into the reservoir to deliver the medication to the patient. Often, the means for driving the plunger comprises a telescoping screw drive set in which an end gear telescopes outward when driven in a rotational manner in one direction. Other systems use a threaded rod that is rotated to drive a nut connected to the plunger; rotation of the rod drives the nut upward, driving the plunger into the reservoir. Other systems use a scissoring system to drive the plunger into the reservoir. In general, the mechanism for all these systems usually involves rotation of a part that drives the plunger, and the rotation is always in the same direction.

[0004] One problem with all of these prior art plunger drive mechanisms is that they require complex methods to address overdose issues. Such issues can arise when a runaway motor event occurs. In such an event, the motor that drives the plunger through any of the aforementioned mechanisms continues to operate after the intended dose has been delivered, thus causing administration to continue and the patient to be overdosed.

[0005] It would be desirable to provide a plunger drive mechanism that avoids the problem of runaway motor events and does so in a cost-effective and simple manner. The present invention provides an elegant, mechanical, always-on guard against runaway motor events. The present invention also provides accurate and reproducible dosing in microdosing syringe pump systems. Summary of the Invention [Problem to be solved by the invention]

[0006] An aspect of the present invention is to provide a syringe for a microdosing syringe pump. [Means for solving the problem]

[0007] Disclosure Overview This section provides a general overview of the present disclosure and is not intended to be construed as an exhaustive disclosure of its entire scope or all features, aspects, and objectives.

[0008] One aspect of the invention is a syringe for use in a microdosing syringe pump, the syringe including a reservoir having an outlet port, a plunger having a track, the plunger received within a portion of the reservoir, and a plunger driver including a gear connected to one end of a shaft and a pin disposed adjacent the other end of the shaft, the plunger driver received within the plunger and the pin disposed within and engaging the track, such that rotation of the gear in a first direction advances the plunger within the reservoir a first distance as the pin moves within the track, and rotation of the gear in a second direction opposite the first direction advances the plunger within the reservoir a second distance as the pin moves within the track, the second distance being greater than the first distance.

[0009] Another aspect of the present disclosure is to provide a syringe for a microdosing syringe pump, the syringe including: a reservoir having an outlet port; a plunger having a track, the track including a plurality of slots, each slot including a linear run, a cam run, and an end point, the plunger received within a portion of the reservoir; and a plunger drive mechanism including a gear connected to one end of a shaft and a pin disposed adjacent the other end of the shaft, the plunger drive mechanism received within the plunger, the pin disposed within and engaging the track, wherein rotation of the gear in a first direction advances the plunger a first distance into the reservoir when the pin moves within a first slot of the plurality of slots, and rotation of the gear in a second direction opposite the first direction advances the plunger a second distance greater than the first distance when the pin moves within the second slot.

[0010] These and other features and advantages of the present disclosure will become apparent to those skilled in the art from the detailed description herein. The drawings accompanying the detailed description are now described.

[0011] The drawings described herein are for illustrative purposes of only selected embodiments, not all implementations, and are not intended to limit the disclosure to only those actually shown. With this in mind, various features and advantages of exemplary embodiments of the present disclosure will become apparent to those of ordinary skill in the art from the following description and appended claims, when considered in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 shows a reservoir for a syringe designed in accordance with the present invention. [Figure 2] FIG. 1 shows a plunger for a syringe designed in accordance with the present invention. [Figure 3] 1 illustrates a plunger advancement device for a syringe designed in accordance with the present invention. [Figure 4] 4 shows an assembled syringe designed in accordance with the present invention in an initial loading position using the reservoir of FIG. 1, the plunger of FIG. 2, and the plunger advancement device of FIG. 3. [Figure 5] 5 shows the assembled syringe of FIG. 4 after partial advancement of the plunger into the reservoir. [Figure 6] 3 is a schematic diagram illustrating the track system of the plunger shown in FIG. 2 and designed in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Detailed Description of Disclosure In the following description, details are set forth to provide an understanding of the present disclosure.

[0014] For clarity, exemplary aspects are described herein to convey the scope of the present disclosure to those skilled in the relevant arts. Numerous specific details are set forth, such as examples of specific components, devices, and methods, to provide a thorough understanding of various aspects of the present disclosure. It will be apparent to those skilled in the art that certain details, such as well-known processes, well-known device structures, well-known technologies, etc., are already well-understood by those skilled in the art and therefore need not be described herein, and that the exemplary embodiments may be embodied in many different forms, none of which should be construed as limiting the scope of the present disclosure.

[0015] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" may be intended to include the plural forms unless the context clearly dictates otherwise. The terms "comprise," "comprising," "including," "including," and "having" are inclusive and thus specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, procedures, and operations described herein should not be construed as necessarily requiring their performance in the particular order described or illustrated, unless specifically identified as such. It should also be understood that additional or alternative steps may be employed.

[0016] When an element or structure is referred to as "adjacent," "engaged," "connected," "coupled," "operably connected," or "in operative communication with" another element or structure, it may be directly abutting, engaged, connected, or coupled to the other element or layer, or intervening elements or structures may be present. In contrast, when an element is referred to as "directly abutting," "directly engaged," "directly connected," or "directly coupled" to another element or structure, there may be no intervening elements or layers. Other words used to describe relationships between elements should be interpreted similarly (e.g., "directly between" as opposed to "between," "directly adjacent" as opposed to "adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0017] Terms such as first, second, and third may be used herein to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. When used herein, the terms "first," "second," and other numbers do not imply sequence or order unless clearly and explicitly dictated by the context. Thus, without departing from the teachings of the exemplary embodiments, a first element, component, region, layer, or section described below could be referred to as a second element, component, region, layer, or section.

[0018] For purposes of explanation herein, the terms "top," "bottom," "right," "left," "rear," "front," "vertical," "horizontal," and their derivatives will refer to the present invention as oriented in the figures. However, it should be understood that the present disclosure may contemplate various alternative orientations and sequences of steps, unless expressly specified to the contrary. It should also be understood that the specific devices and processes illustrated in the accompanying drawings and described in the following detailed description are illustrative embodiments of the inventive concepts defined in the appended claims. Therefore, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered limiting, unless the claims expressly state otherwise.

[0019] A syringe contains a reservoir, also known as the barrel of the syringe. In this specification and claims, the two terms will be used interchangeably. A typical syringe includes at least a barrel, a plunger, and a plunger drive mechanism.

[0020] FIG. 1 shows a reservoir for a syringe designed in accordance with the present invention, generally designated 10. Reservoir 10 is generally cylindrical in shape and includes a barrel wall 12 extending from an open first end 14 to a closed second end 16. Second end 16 includes an outlet port 18 through which medication exits and is dispensed from reservoir 10. Outlet port 18 is ultimately connected to a patient to deliver the medication to the patient. Reservoir 10 preferably includes an optional fill port 20. Alternatively, reservoir 10 could be filled through open end 14 or through outlet port 18, as known to those skilled in the art. Reservoir 10 is preferably formed of a one-piece design. It may be formed from a non-metallic polymeric material, such as a thermoplastic material, by way of example only. Alternatively, it may be formed from a metallic material, such as a stainless steel or metal alloy, by way of example only.

[0021] FIG. 2 illustrates a plunger for a syringe designed in accordance with the present invention, generally designated 40. The plunger 40 includes a cylindrical plunger barrel 42 sized to fit snugly inside the reservoir 10. This means that the outer diameter of the plunger 40 is only slightly smaller than the inner diameter of the reservoir 10. The plunger barrel 42 has an open end 44 opposite a closed end 46. The closed end 46 includes an integral piston 48 having a front surface 50 with a beveled rim 52 and a groove 54. The groove 54 includes a front wall 56 opposite a rear wall 58 and a bottom 60. The groove 54 is for receiving an O-ring, also known as an O-ring gland. For clarity, the O-ring is not shown, but those skilled in the art will readily understand that an O-ring is typically used to provide a seal between the piston 48 and the interior wall of the reservoir 10 to prevent leakage of medication from the reservoir 10 when the plunger 40 is advanced within the reservoir 10. Those skilled in the art will understand the design considerations for selecting an O-ring with the appropriate volume fill factor, compression rate, and elongation rate for the groove 54, as well as the elastomer or rubber material from which the O-ring is formed. Also shown in FIG. 2 is an optional through-hole 62 extending from the exterior of the plunger barrel 42 to the interior of the barrel 42. The optional through-hole 62 is intended to facilitate assembly of the components, as described herein, in one embodiment. A portion of the interior wall of the plunger barrel 42 includes a track 64. If an optional through-hole 62 is present, the track 64 then faces the through-hole 62, as shown. The track 64 includes a plurality of slots 66, which in one embodiment are cut into the interior wall of the plunger barrel 42. As shown in one embodiment, each slot 66 includes a linear run 68, a cam run 70, and an end point 72. The cam run 70 is also known as a cam surface. In this embodiment, the cam run 70 is angled away from the piston 48. Each slot 66 connects to adjacent slots 66 along the length of the track. The slots 66 may have shapes other than those shown, as will be understood by those skilled in the art. The slots 66 are separated from one another by separator walls 74.The slots 66 form a zigzag pattern along the track 64. Each zig and zag portion is designed to deliver an equivalent dose, as described herein. The plunger 40 may also include a bypass track 120, as described in FIG. 6. While the track 64 is shown cut into the interior wall of the plunger barrel 42 and does not penetrate therethrough, this need not be the case. The plunger 40 may be formed from a material of sufficient strength to allow the track 64 to be cut completely through the plunger barrel 42, if desired. The plunger 40 is preferably formed as a unitary piece and may be formed from a polymeric material, such as a thermoplastic, or a metal, such as stainless steel or a metal alloy.

[0022] FIG. 3 illustrates a plunger advancement device for a syringe designed in accordance with the present invention, generally designated 90. Plunger advancement device 90 includes a gear 92, such as a spur gear, at one end. A shaft 94 is secured to gear 92, and on the opposite side of gear 92 is a pin 96 that is received in a through hole 98 in shaft 94. Pin 96 may be secured in place using an adhesive or may be friction-fit into through hole 98. In one embodiment, pin 96 is secured to through hole 98 prior to assembly of the syringe, or in another embodiment, it is placed within through hole 98 during assembly, as described herein. Gear 92 is operably connected to a motor of a microdose syringe pump (not shown), which is used to rotate plunger advancement device 90 in both clockwise and counterclockwise directions. This may be accomplished using one or more drive gears between the driven shaft of the motor and gear 92, as will be understood by those skilled in the art. This drive of gear 92 will cause pin 96 to rotate in a clockwise or counterclockwise direction while remaining in the same plane of rotation in both directions. Plunger advancer 90 may be formed as a unitary piece including pin 96, as described herein. Plunger advancer 90 and pin 96 may be formed from a polymeric composition, such as a thermoplastic composition. Alternatively, plunger advancer 90 and pin 96 may be formed from a metallic material, such as stainless steel or a metal alloy.

[0023] FIG. 4 illustrates an assembled syringe, generally designated 110, designed in accordance with the present invention. The syringe 110 is shown in an initial loading position and includes the reservoir 10, plunger 40, and plunger advancement device 90. The fill port 20, if present, is positioned so that the reservoir 10 can be filled when the syringe 110 is in this position and the piston 48 is positioned just inside the reservoir. In use, the syringe 110 will be placed inside a microdosing syringe pump (not shown) and will be supported at least by the closed end 16 of the reservoir 10 and the gear 92. It may also be supported by the open end 14 of the reservoir 10 when placed inside the microdosing syringe pump. It is supported to prevent any axial or longitudinal movement of the reservoir 10 during use, particularly when the plunger 40 is telescopically engaged within the reservoir 10 by the plunger advancement device 90. The plunger advancer 90, when driven by the gear 92, can be rotated in both a clockwise and counterclockwise direction. The plunger advancer 90 is supported at least at the gear 92 to prevent longitudinal movement of the shaft 94 during its rotation and use. In one embodiment, as described above, the plunger 40 includes a throughbore 62 opposite the track 64. In that embodiment, to assemble the syringe 110, the plunger advancer 90 without the pin 96 is inserted into the open end 44 of the plunger 40. The throughbore 98 of the shaft 94 is then aligned with the throughbore 62 of the plunger 40, and the pin 96 can be inserted into the throughbore 98 of the shaft 94 using the throughbore 62 of the plunger 40. The pin 96 has a length sufficient to fully engage and move within the track 64 when it is received within the throughbore 98. As shown in FIG. 4, when the syringe 110 is in this position, the pin 96 is positioned in the slot 66 closest to the piston 48 .

[0024] FIG. 5 shows the assembled syringe 110 of FIG. 4 after partial advancement of the plunger 40 into the reservoir 10. Advancement is caused by rotation of the plunger advancement device 90, and thereby the pin 96, in both clockwise and counterclockwise directions. As the direction of rotation is changed, the pin 96 moves within and engages the track 64, moving from one slot 66 to the next, driving the plunger 40 into the reservoir 10 and thus forcing the medication out the outlet port 18. While the shaft 94 is rotated in each direction, the plunger advancement device 90 does not change longitudinal position, but the plunger 40 moves longitudinally within the reservoir 10. This movement is best shown in FIG. 6.

[0025] FIG. 6 is a schematic diagram showing the track 64 of the plunger 40 designed in accordance with the present invention, as shown in FIG. 2 . It shows the track 64 in more detail and also shows an optional bypass track 120 that, in one embodiment, can be used to assemble the syringe 110. In one embodiment, the pin 96 is secured within the through-hole 98 prior to assembly of the syringe 110, and the bypass track 120 is used to allow the plunger advancement device 90 to be inserted into the plunger 40. In this assembly method, the pin 96 is inserted into the plunger 40 at the pin entry point of the bypass track 120, after which the pin 96 can advance within the bypass track 120 to fully insert the shaft 94 into the plunger 40. When the shaft 94 is fully inserted into the plunger 40, the pin 96 will be positioned at the pin rest point 126 at the beginning of the track 64. In embodiments without bypass track 120, pin 96 is inserted into through-hole 62 and through-hole 98 when they are aligned. In embodiments with bypass channel 120, bypass channel 120 is accessible only at the beginning of use of syringe 110 in the microdosing syringe pump. Once dose delivery begins, bypass channel 120 can no longer be accessed by pin 96. If the motor rotates gear 92 in the wrong direction at the start of dosing, pin 96 will lock into pin rest point 126, plunger 40 will rotate in place, and no dose will be dispensed. Dosing will begin after rotation of gear 92 is reversed, as described herein. In both embodiments, pin 96 is positioned at pin rest point 126 before the first dose of medication is dispensed from reservoir 10.

[0026] The mechanism of syringe 110 will be explained with particular reference to FIG. 6. For ease of explanation, upward motion in FIG. 6 will be explained as a clockwise rotation of shaft 94, and downward motion in FIG. 6 will be explained as a counterclockwise rotation of shaft 94, although one skilled in the art will understand that it could also be described in the opposite sense. Referring back to FIG. 6, when the first dose is administered, gear 92 is rotated in a clockwise direction, causing pin 96 to move from pin rest point 126 along first path of travel 128 to end point 130 of first path of travel 128. First path of travel 128 includes linear run 68 followed by cam run 70 and end point 72. As the pin 96 is rotated, due to the shape of the cam run 70, which slopes downward away from the piston 48, the pin 96 will move the plunger 40 into the reservoir 10 as it rotates against the cam run 70. This occurs because the pin 96 is always in the same plane of rotation during rotation, regardless of the direction of rotation, and the cam run 70 has a slope that points away from the piston 48. Therefore, the plunger advancement device 90 cannot move longitudinally, and the rotation of the pin 96 against the cam run 70 causes the plunger 40 to telescope away from the gear 92 and into the reservoir 10. Once the pin 96 reaches the end point 72, there will be no further advancement of the plunger 40 into the reservoir 10, even if the gear 92 is further rotated clockwise. Instead, the plunger 40 will simply rotate in place within the reservoir 10. This is a safety feature that prevents overdosing in the event that the microdosing syringe pump motor (not shown) malfunctions and continues to rotate the gear clockwise. In summary, rotation of gear 92 in a first direction advances plunger 40 a first distance into reservoir 10, delivering a first dose. In normal function, the next dose is delivered by reversing the rotation of gear 92 and rotating it in a counterclockwise manner. As gear 92 is driven in a counterclockwise rotation, pin 96 moves along second dose pin travel path 132 from pin position 130 to pin position 134. Second dose travel path 132 includes an initial linear run 68 followed by a cam run 70 that terminates at endpoint 72.Again, in the event of a runaway motor malfunction, once pin 96 reaches pin position 134, continued counterclockwise rotation will not advance another dose; plunger 40 will simply rotate with reservoir 10 without further advancement. Thus, rotation of gear 92 in a second direction, opposite the first direction, will advance plunger 40 a further distance into reservoir 10 to deliver the second dose. For delivery of a third dose, rotation of gear 92 is alternated in the opposite counterclockwise direction, and pin 96 moves from pin position 134 to pin position 138 along a third dose travel path 136. Third dose travel path 136 includes a straight run 68 followed by a cam run 70 and an endpoint 72. As can be seen from the figure, continuing to reverse the direction of rotation of gear 92 after each dose will continue to advance plunger 40 further into reservoir 10 until pin 96 reaches the end of track 64 at open end 44 of plunger 40. Thus, one can see how pin 96 moves through the zigzag pattern of track 64, delivering a dose at each zig and zag, and that each dose is the same. The length of cam run 70 relative to the width of separation wall 74 ensures that pin 96 cannot bounce back into the straight run 68 of slot 66 that it previously traveled when it descends along cam run 70 to end point 72 of slot 66 and the rotation of gear 92 is reversed to deliver the next dose. As described above, slot 66 can have other shapes than that shown, so long as the slot shape includes a cam run 70 shape that advances plunger 40 into reservoir 10 when gear 92 is driven in one rotational direction and further into reservoir 10 when gear 92 is driven in the opposite rotational direction. As can be understood from this description, when syringe 110 is used as described above with alternating rotational directions applied to gear 92, plunger 40 moves further away from gear 92 and telescopes into reservoir 10. Each change in rotational direction advances plunger 40 further into reservoir 10.Once pin 96 reaches the end of track 64, plunger 40 can no longer be driven further into reservoir 10, and any rotation of gear 92 simply rotates plunger 40 in place within reservoir 10. The relative positions of reservoir 10 and plunger advancer 90 do not change within the microdosing syringe pump during use. Plunger advancer 90 only rotates forward and backward, with no longitudinal movement, and similarly, reservoir 10 has no longitudinal movement.

[0027] As described, the syringe 110 according to the present invention is designed for use in microdosing syringe pumps known to those skilled in the art. The present invention prevents any potential overdose of medication caused by a runaway motor within the syringe pump continuing to drive gear 92 in a predetermined rotational direction. This safety feature is a result of the mechanical design of track 64, and therefore, the safety feature is always "on" in this syringe 110. Microdosing syringe pumps are commonly used to deliver medications such as insulin, other hormones, chemotherapy drugs, antibiotics, and painkillers. Therefore, the need to ensure accurate dosing is crucial, and the present invention ensures that this occurs. The rotational drive direction of the motor found in such microdosing syringe pumps can be controlled by switching electrical signals and via software, as known in the art. The present invention is also advantageous because it eliminates the need for precision motor control and a motor encoder system in the syringe pump. A preferred feature of the present invention is to include some over-rotation of the pin 96 with each dosing cycle as the pin 96 reaches the end point 72 of each slot 66. This ensures that the pin 96 reaches the end point 72 with each rotation for proper dosing. It also helps allow for manufacturing tolerances that do not need to be tightly controlled in the manufacturing process, which alleviates the need for precise control when rotation is reversed. The microdosing syringe pump will include software to control the function of the motor and monitor the required and dispensed doses. For example, in some cases, the software may instruct the motor to engage in three consecutive dosing cycles to deliver the appropriate amount of medication. In other instances, a single dose will be delivered at a time. Furthermore, the software may instruct the motor to deliver a dose every hour. Such dose control by software is known to those skilled in the art and will not be further described herein.

[0028] The foregoing disclosure has been described in accordance with relevant legal standards; therefore, the description is illustrative rather than limiting in nature. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Variations and modifications to the disclosed embodiments will be apparent to those skilled in the art and may fall within the scope of the present disclosure. Accordingly, the scope of legal protection afforded this disclosure can only be determined by studying the following claims.

Claims

1. A syringe, the syringe comprising: a reservoir having an outlet port; a plunger having a track, the plunger being received within a portion of the reservoir; a plunger drive mechanism including a gear connected to one end of a shaft and a pin disposed adjacent the other end of the shaft, the plunger drive mechanism being received within the plunger, the pin being disposed within and engaging the track; Rotation of the gear in a first direction advances the plunger a first distance into the reservoir as the pin moves within the track, and rotation of the gear in a second direction opposite the first direction advances the plunger a further distance into the reservoir as the pin moves within the track.

2. 10. The syringe of claim 1, wherein the track comprises a plurality of slots.

3. 3. The syringe of claim 2, wherein the pin moves within a first slot of the plurality of slots when the gear is rotated in the first direction, and moves within a second slot of the plurality of slots when the gear is rotated in the second direction.

4. 3. The syringe of claim 2, wherein each of the slots includes a linear run, a cam run, and an end point.

5. 3. The syringe of claim 2, wherein the track and the plurality of slots are cut into an inner wall of the plunger.

6. 3. The syringe of claim 2, wherein each of the plurality of slots is separated from adjacent slots by a separation wall.

7. 3. The syringe of claim 2, wherein the plurality of slots form a zigzag pattern within the track.

8. 10. The syringe of claim 1, wherein the plunger further includes a bypass track in communication with the track.

9. 10. The syringe of claim 1, wherein the plunger further comprises a piston having an O-ring.

10. 5. The syringe according to claim 4, wherein the plunger further includes a piston, and the cam running portion is inclined in a direction away from the piston.

11. 3. The syringe of claim 2, wherein the track and the plurality of slots are formed through a wall of the plunger.

12. A syringe, the syringe comprising: a reservoir having an outlet port; a plunger having a track, the track comprising a plurality of slots, each of the slots comprising a straight run, a cam run, and an end point, the plunger being received within a portion of the reservoir; a plunger drive mechanism including a gear connected to one end of a shaft and a pin disposed adjacent the other end of the shaft, the plunger drive mechanism being received within the plunger, the pin being disposed within and engaging the track; Rotation of the gear in a first direction advances the plunger a first distance into the reservoir as the pin moves within a first slot of the plurality of slots, and rotation of the gear in a second direction opposite the first direction advances the plunger a further distance into the reservoir as the pin moves within a second slot of the plurality of slots.

13. 13. The syringe of claim 12, wherein the first slot of the plurality of slots is adjacent to the second slot of the plurality of slots.

14. 13. The syringe of claim 12, wherein the track and the plurality of slots are cut into an interior wall of the plunger.

15. 13. The syringe of claim 12, wherein each of the plurality of slots is separated from adjacent slots by a separation wall.

16. 13. The syringe of claim 12, wherein the plurality of slots form a zigzag pattern within the track.

17. 13. The syringe of claim 12, wherein the plunger further includes a bypass track in communication with the track.

18. 13. The syringe of claim 12, wherein the plunger further comprises a piston having an O-ring.

19. 13. The syringe according to claim 12, wherein the plunger further includes a piston, and the cam running portion is inclined in a direction away from the piston.

20. 13. The syringe of claim 12, wherein the track and the plurality of slots are cut through a wall of the plunger.

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