Syringe with bi-directional plunger advancement mechanism for micro-dosing syringe pump

Abstract

A syringe for a micro-dosing 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, a plunger driver including a gear connected to one end of a shaft and a pin located near an opposite end of the shaft, the plunger driver received within the plunger, the pin located within the track and engaging the track. In use, rotation of the gear in a first direction advances the plunger into the reservoir a first distance as the pin travels in the track, and rotation of the gear in a second direction opposite the first direction advances the plunger into the reservoir a further distance as the pin travels in the track. This design prevents over-dosing in the event of a runaway motor failure.

Description

Technical Field

[0001] This disclosure generally relates to a syringe for a micro-dosing syringe pump, and more particularly to a syringe having a bidirectional propulsion mechanism and runaway pump motor safety features. Background Technology

[0002] This section provides background information, which is not necessarily prior art to the inventive concept associated with this disclosure.

[0003] Microdosing syringe pumps are known in the art and are frequently used to deliver medications such as insulin, other hormones, chemotherapy drugs, antibiotics, and analgesics (to name just a few). These devices include a syringe, which typically comprises a reservoir, a plunger, and a means for driving the plunger into the reservoir to deliver the medication to the patient. The means for driving the plunger typically includes a retractable screw drive that extends outward when an end gear is rotated in one direction. Other systems use a threaded rod that is rotated to drive a nut connected to the plunger; the rotation of the rod drives the nut upward and the plunger into the reservoir. Other systems use a scissor system to drive the plunger into the reservoir. Generally, for all these systems, the mechanism typically involves rotation of the parts driving the plunger, and the rotation is always in the same direction.

[0004] One problem with all these existing plunger actuator mechanisms is that they require complex methods to address the problem of overdose. This problem can arise when a runaway motor event occurs. In such an event, the motor driving the plunger via one of the aforementioned mechanisms continues to operate after the intended dose has been delivered, thus continuing drug administration and potentially leading to an overdose on the patient.

[0005] The aim is to provide a plunger actuator mechanism that avoids the problem of runaway motor events and does so in a cost-effective and simple manner. This invention provides an elegant, mechanical, always-on protective device against runaway motor events. It also provides accurate and repeatable dosing in microdosing syringe pump systems. Summary of the Invention

[0006] This section provides a general overview of this disclosure and is not intended to be construed as a full disclosure of its entire scope or all its features, aspects and objectives.

[0007] One aspect of the invention is a syringe for a microdosing syringe pump. The syringe includes: a reservoir having an outlet port; a plunger having a track, wherein the plunger is received within a portion of the reservoir; a plunger driver including a gear connected to one end of a shaft and a pin located near the opposite end of the shaft, wherein the plunger driver is received within the plunger, and wherein the pin is located within the track and engages the track; and thus, when the pin travels in the track, rotation of the gear in a first direction advances the plunger into the reservoir a first distance, and rotation of the gear in a second direction opposite to the first direction advances the plunger into the reservoir a second distance, wherein the second distance is greater than the first distance.

[0008] Another aspect of this disclosure is to provide a syringe for a microdosing syringe pump. The syringe includes: a reservoir having an outlet port; a plunger having a track including a plurality of slots, each slot including a straight section, a cam section, and an end point, wherein the plunger is received within a portion of the reservoir; a plunger driver including a gear connected to one end of a shaft and a pin located near the opposite end of the shaft, the plunger driver being received within the plunger, wherein the pin is located within the track and engages the track; and thus, when the pin travels in a first slot of the plurality of slots, rotation of the gear in a first direction advances the plunger into the reservoir a first distance, and when the pin travels in a second slot of the plurality of slots, rotation of the gear in a second direction opposite to the first direction advances the plunger into the reservoir a second distance, wherein the second distance is greater than the first distance.

[0009] These and other features and advantages of this disclosure will become more apparent to those skilled in the art from the detailed description herein. The accompanying drawings illustrate specific embodiments. Attached Figure Description

[0010] The accompanying drawings described herein are for illustrative purposes only, and not for all embodiments, and are not intended to limit this disclosure to what is actually shown. In view of this, various features and advantages of exemplary aspects of this disclosure will become apparent to those skilled in the art when considered in conjunction with the drawings, based on the following written description and the appended claims, wherein:

[0011] Figure 1 The storage container of the syringe designed according to the present invention is shown;

[0012] Figure 2 The plunger of a syringe designed according to the present invention is shown;

[0013] Figure 3 A plunger actuator for a syringe designed according to the present invention is shown;

[0014] Figure 4It shows the use of Figure 1 storage Figure 2 plunger and Figure 3 The plunger pusher of the present invention is an assembled syringe designed according to the present invention, the assembled syringe being in the initial loading position;

[0015] Figure 5 This shows the process after the plunger has partially advanced into the reservoir. Figure 4 The assembled syringe; and

[0016] Figure 6 It is shown Figure 2 The diagram shows a plunger track system designed according to the present invention. Detailed Implementation

[0017] In the following description, details are set forth to provide an understanding of this disclosure.

[0018] For clarity, exemplary aspects are discussed herein to convey the scope of this disclosure to those skilled in the art. Numerous specific details, such as examples of specific components, apparatuses, and methods, are set forth to provide a thorough understanding of various aspects of this disclosure. It will be apparent to those skilled in the art that specific details, such as well-known processes, well-known apparatus structures, and well-known techniques, are not required herein to be discussed, as they are well understood by those skilled in the art, and that exemplary embodiments may be embodied in many different forms, and neither should be construed as limiting the scope of this disclosure.

[0019] The terminology used herein is for descriptive purposes only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. The terms “comprising,” “including,” “containing,” and “having” are inclusive and thus specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. It should also be understood that additional or alternative steps may be employed.

[0020] When an element or feature is referred to as “on another element or feature,” “joined to,” “connected to,” “linked to,” “operably connected to,” or “operably connected to” another element or feature, it may be directly on, joined to, connected to, or linked to another element or feature, or there may be intermediate elements or features present. Conversely, when an element is referred to as “directly on another element or feature,” “directly joined to,” “directly connected to,” or “directly linked to” another element or feature, there may be no intermediate elements or layers present. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” vs. “directly between,” “adjacent” vs. “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more items associated with the listed items.

[0021] While the terms "first," "second," "third," etc., may be used herein to describe various elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or segment from another. Terms such as "first," "second," and other numerical terms used herein do not imply order or sequence unless the context clearly indicates otherwise. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or segment discussed below may be referred to as a second element, component, region, layer, or segment.

[0022] For the purposes of this description, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and their derivatives should be used in connection with the invention as oriented in the figures. However, it should be understood that this disclosure may take various alternative orientations and sequences of steps unless expressly stated otherwise. It should also be understood that the specific devices and processes shown in the figures and described in the following description are exemplary aspects of the inventive concept defined herein. Therefore, specific dimensions and other physical characteristics relating to the aspects disclosed herein should not be considered limiting unless the claims expressly state otherwise.

[0023] A syringe includes a reservoir, also known as the syringe barrel. These two terms are used interchangeably in this specification and claims. A typical syringe includes at least a barrel, a plunger, and a plunger actuator.

[0024] exist Figure 1In the diagram, a reservoir for a syringe designed according to the present invention is generally shown as 10. The reservoir 10 is generally cylindrical and includes a barrel wall 12 extending from an open first end 14 to a closed second end 16. The second end 16 includes an outlet port 18 through which medication is dispensed from the reservoir 10. The outlet port 18 is ultimately connected to a patient for delivery of medication to the patient. The reservoir 10 preferably includes an optional filling port 20. Alternatively, as those skilled in the art will know, the reservoir 10 can be filled either through the open end 14 or through the outlet port 18. The reservoir 10 is preferably formed as a single unit. It can be formed from a non-metallic polymeric material, such as a thermoplastic material. Alternatively, it can be formed from a metallic material, such as stainless steel or a metal alloy.

[0025] exist Figure 2 In the diagram, the plunger for a syringe designed according to the present invention is generally shown as 40. The plunger 40 includes a cylindrical plunger barrel 42, the dimensions of which are adapted for a tight fit within a reservoir 10. This means that the outer diameter of the plunger 40 is 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 end 50 with an inclined edge 52 and a recess 54. The recess 54 includes a front wall 56 opposite a rear wall 58 and a bottom 60. The recess 54 is used to receive an O-ring, also known as an O-ring seal. For clarity, the O-ring is not shown, but those skilled in the art will readily understand that O-rings are commonly used to provide a seal between the piston 48 and the inner wall of the reservoir 10 to prevent leakage of medication from the reservoir 10 as the plunger 40 is advanced into the reservoir 10. Those skilled in the art will understand the design considerations for selecting an O-ring, which has an appropriate volume fill percentage, compression percentage, stretch percentage, and the elastomer or rubber material forming the O-ring to suit the groove 54. Figure 2An optional through-hole 62 is also shown, which enters the interior of the plunger cylinder 42 from the outside. In one embodiment, the optional through-hole 62 enables assembly of components, as will be explained herein. A portion of the inner wall of the plunger cylinder 42 includes a track 64. As shown, when the optional through-hole 62 is present, the track 64 is opposite to the through-hole 62. The track 64 includes a plurality of slots 66, which, in one embodiment, cut into the inner wall of the plunger cylinder 42. As shown in one embodiment, each slot 66 includes a straight section 68, a cam section 70, and an end point 72. The cam section 70 is also referred to as a cam surface. In this embodiment, the cam section 70 is inclined in a direction away from the piston 48. Each slot 66 connects to an adjacent slot 66 along the length of the track 64. As those skilled in the art will understand, the slots 66 may have shapes different from those shown. The slots 66 are separated from each other by partition walls 74. The slots 66 form a zigzag pattern along the track 64. As described in this article, each zig and each zag is designed to deliver an equal dose to each other. Figure 6 As described, plunger 40 may also include bypass rail 120. Although rail 64 is shown to cut into the inner wall of plunger cylinder 42 and not through it, this is not necessary. If desired, plunger 40 may be formed of a material of sufficiently high strength to allow rail 64 to completely cut through the wall of plunger cylinder 42. Plunger 40 is preferably formed as a single piece and may be formed of polymeric materials such as thermoplastics, or of metals such as stainless steel or metal alloys.

[0026] exist Figure 3In the diagram, a plunger actuator for a syringe designed according to the present invention is generally shown as 90. The plunger actuator 90 includes a gear 92, such as a spur gear, at one end. A shaft 94 is fixed to the gear 92, and opposite the gear 92 is a pin 96 received in a through-hole 98 of the shaft 94. The pin 96 can be held in place using an adhesive, or it can be frictionally fitted into the through-hole 98. In one embodiment, the pin 96 is fixed in the through-hole 98 before the syringe is assembled, and in another embodiment, as explained herein, the pin 96 is placed in the through-hole 98 during assembly. The gear 92 is operatively connected to a motor in a microdosing syringe pump (not shown), and the motor is used to rotate the plunger actuator 90 in both clockwise and counterclockwise directions. As those skilled in the art will understand, this can be achieved by using one or more drive gears between the driven shaft of the motor and the gear 92. This actuation of the gear 92 will cause the pin 96 to rotate in either a clockwise or counterclockwise direction while remaining in the same plane of rotation in both directions. As described herein, the plunger 90 can be formed as an integral part including the pin 96. The plunger 90 and the pin 96 can be formed from a polymer composition, such as a thermoplastic composition. Alternatively, the plunger 90 and the pin 96 can be formed from a metallic material, such as stainless steel, a metal alloy.

[0027] Figure 4An assembled syringe, generally designated 110, is shown according to the invention. The syringe 110 is shown in its initial loaded position and includes a reservoir 10, a plunger 40, and a plunger thruster 90. When a filling port 20 is present, it is positioned such that the reservoir 10 can be filled when the syringe 110 is in this position and the piston 48 is directly inside the reservoir 10. In use, the syringe 110 will be located inside a microdosing syringe pump (not shown) and will be supported at least at the closed end 16 of the reservoir 10 and the gear 92. When located inside the microdosing syringe pump, it may also be supported at the open end 14 of the reservoir 10. It is supported to prevent any axial or longitudinal movement of the reservoir 10 during use, particularly when the plunger 40 is extended or retracted into the reservoir 10 by the plunger thruster 90. The plunger thruster 90 can rotate clockwise and counterclockwise when driven by the gear 92. The plunger pusher 90 is supported at least at the location of the gear 92 to prevent longitudinal movement of the shaft 94 during its rotation and use. In one embodiment, as discussed above, the plunger 40 includes a through-hole 62 opposite to the track 64. To assemble the syringe 110 in this embodiment, the plunger pusher 90 without the pin 96 is inserted into the open end 44 of the plunger 40. The through-hole 98 in the shaft 94 is then aligned with the through-hole 62 in the plunger 40, and the pin 96 can be inserted into the through-hole 98 in the shaft 94 using the through-hole 62 in the plunger 40. The length of the pin 96 is sufficient to fully engage the track 64, and it straddles the track 64 when received in the through-hole 98. Figure 4 As shown, when the syringe 110 is in this position, the pin 96 is located in the slot 66 closest to the piston 48.

[0028] Figure 5 This shows the process after the plunger 40 is partially advanced into the reservoir 10. Figure 4 The assembled syringe 110. This propulsion is caused by the rotation of the plunger pusher 90, which causes the pin 96 to rotate alternately in both clockwise and counterclockwise directions. With the alternation of rotational directions, the pin 96 mounts and engages in the track 64, moves from one slot 66 to the next slot, and drives the plunger 40 into the reservoir 10, thus driving the drug out from the outlet port 18. Throughout the entire time the shaft 94 rotates in each direction, the plunger pusher 90 does not change its longitudinal position, but the plunger 40 moves longitudinally into the reservoir 10. Figure 6 This better illustrates the movement.

[0029] Figure 6 It is shown Figure 2The diagram shows a schematic of the track 64 of the plunger 40 designed according to the present invention. It shows the track 64 in more detail and also shows an optional bypass track 120, which in one embodiment can be used to assemble the syringe 110. In one embodiment, where the pin 96 is secured in the through-hole 98 before the syringe 110 is assembled, the bypass track 120 allows the plunger pusher 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 124 in the bypass track 120, and then the shaft 94 can be fully inserted into the plunger 40, with the pin 96 riding on the bypass track 120. When the shaft 94 is fully inserted into the plunger 40, the pin 96 will be located at the pin rest point 126 at the beginning of the track 64. In embodiments without the bypass track 120, the pin 96 is inserted into both the through-hole 62 and the through-hole 98 when the through-hole 62 is aligned with the through-hole 98. In embodiments with bypass channel 120, bypass channel 120 is only accessible when the syringe 110 in the microdosing syringe pump is first used. Once dosing begins, bypass channel 120 can no longer be accessed by pin 96. If, at the start of dosing, the motor rotates gear 92 in the wrong direction, pin 96 will be pinned into pin rest point 126, and plunger 40 will rotate in place without a dose being dispensed. As described herein, dosing will begin after gear 92 has rotated in the opposite direction. In both embodiments, pin 96 is located at pin rest point 126 before the first dose of medication is dispensed from reservoir 10.

[0030] Please refer to the specific details. Figure 6 Describe the mechanical structure of syringe 110. For ease of description, Figure 6 The upward motion will be described as a clockwise rotation of axis 94, while Figure 6 The downward motion will be described as a counterclockwise rotation of axis 94; however, those skilled in the art will understand that it can be described in the opposite orientation. Still refer to Figure 6When the first dose is dispensed, gear 92 rotates clockwise, and pin 96 is driven from pin rest point 126 along the first travel path 128 to end point 130 of the first travel path 128. The first travel path 128 includes a straight section 68, followed by a cam section 70 and end point 72. Due to the shape of the cam section 70, as pin 96 rotates against the cam section 70, the downwardly inclined portion moving away from piston 48 with the pin 96 will drive plunger 40 into reservoir 10. This occurs because during the rotation of pin 96, pin 96 is always in the same plane of rotation, regardless of the direction of rotation, and cam section 70 has an inclined portion moving away from piston 48. Therefore, plunger pusher 90 cannot move longitudinally, and thus the rotation of pin 96 against cam section 70 causes plunger 40 to move away from gear 92 and into reservoir 10. Once pin 96 reaches end point 72, if gear 92 rotates further clockwise, plunger 40 will not be pushed further into reservoir 10. Instead, the plunger 40 will simply rotate in place within the reservoir 10. This is a safety feature that prevents overdose in the event of a malfunction in the microdosing syringe pump motor (not shown) and continued rotation of the gear 92 in a clockwise manner. In summary, rotation of the gear 92 in the first direction advances the plunger 40 a first distance into the reservoir 10 and delivers the first dose. In normal function, the next dose is delivered by reversing the rotation of the gear 92 to make it rotate counterclockwise. When the gear 92 is driven to rotate counterclockwise, the pin 96 moves from pin position 130 to pin position 134 along the second dose pin travel path 132. The second dose travel path 132 includes an initial straight section 68, followed by a cam section 70 terminating at end point 72. Similarly, in the event of a runaway motor malfunction, once the pin 96 reaches pin position 134, continued counterclockwise rotation will not deliver another dose, and the plunger 40 will simply spin in the reservoir 10 without further advancement. Therefore, the rotation of gear 92 in a second direction opposite to the first direction advances plunger 40 further into reservoir 10 to deliver the second dose. During the delivery of the third dose, the rotation of gear 92 alternates back to the counter-clockwise direction, and pin 96 moves along the third dose travel path 136 from pin position 134 to pin position 138. The third dose travel path 136 includes a straight section 68, followed by a cam section 70 and an end point 72. It can be seen that after each dosing, continuing to reverse the rotation direction of gear 92 will continue to advance plunger 40 further and further into reservoir 10 until pin 96 reaches the end of track 64 at the open end 44 of plunger 40. Thus, it can be seen how pin 96 moves through a zigzag pattern of track 64 to deliver the dose at each zig and zag, and that the dose at each zig and zag is the same.The length of the cam segment 70 relative to the width of the partition wall 74 ensures that once the pin 96 travels down the cam segment 70 to the end point 72 of the slot 66, and the rotation of the gear 92 reverses to deliver the next dose, the pin 96 cannot jump back to the straight section 68 of the previously traveled slot 66. As discussed above, the slot 66 can have other shapes besides those shown in the figures, as long as the shape of the slot includes a cam segment 70 shape that drives the plunger 40 into the reservoir 10 when the gear 92 is driven in one rotational direction, and then further drives the plunger 40 into the reservoir 10 when the gear 92 is driven in the opposite rotational direction. It can be understood from this description that when the syringe 110 is used as described, alternating rotational directions are applied to the gear 92, causing the plunger 40 to extend further away from the gear 92 and into the reservoir 10. Each change in rotational direction drives the plunger 40 further into the 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 merely causes plunger 40 to spin in place within reservoir 10. During use, the relative positions of reservoir 10 and plunger pusher 90 within the microdosing syringe pump do not change. Plunger pusher 90 rotates only back and forth without longitudinal movement, and similarly, reservoir 10 also does not move longitudinally.

[0031] As described, the syringe 110 according to the invention is designed for use in a microdosing syringe pump, as is known to those skilled in the art. The invention prevents any possibility of drug overdose due to an uncontrolled motor in the syringe pump continuing to drive gear 92 in a given direction of rotation. This safety feature is a result of the mechanical design of track 64, and therefore this safety feature is always “on” in the syringe 110. Microdosing syringe pumps are commonly used to deliver drugs such as insulin, other hormones, chemotherapy drugs, antibiotics, and analgesics. Therefore, the need to ensure accurate dosing is crucial, and the invention ensures accurate dosing. The rotational drive direction of the motor in such a microdosing syringe pump can be controlled by switching electrical signals and via software known in the art. The invention is also advantageous because it eliminates the need for fine motor control in the syringe pump and any need for a motor encoder system. A preferred feature of the invention is that once pin 96 reaches the end point 72 of each slot 66, pin 96 includes some over-rotation in each dosing cycle. This ensures that pin 96 reaches end point 72 with each rotation for proper dosing. It also helps to allow manufacturing tolerances to be less strictly controlled during the manufacturing process, and it reduces the need for precise control during rotational reversal. The microdosing infusion pump will include software that controls motor function, monitors the desired dose, and dispenses the dosage. For example, in some cases, the software may instruct the motor to perform three consecutive dosing cycles to deliver the appropriate amount of drug. In other cases, a single dose may be delivered at a time. Furthermore, the software may instruct the motor to deliver one dose per hour. This software-based dose control is known to those skilled in the art and will not be described further herein.

[0032] The foregoing disclosure has been described in accordance with applicable legal standards and is therefore exemplary rather than restrictive in nature. In some example embodiments, well-known processes, known apparatus structures, and known technologies have not been described in detail. Variations and modifications to the disclosed embodiments will be apparent to those skilled in the art and fall within the scope of this disclosure. Therefore, the scope of legal protection provided by this disclosure can only be determined by studying the following claims.

Claims

1. A syringe, the syringe comprising: Storage device, the storage device having an output port; A plunger having a track, the plunger being received within a portion of the reservoir; A plunger driver includes a gear connected to one end of a shaft and a pin located near the opposite end of the shaft, the plunger driver being received inside the plunger, wherein the pin is located inside the rail and engages the rail; Thus, when the pin travels in the track, the rotation of the gear in the first direction pushes the plunger into the reservoir a first distance, and when the pin travels in the track, the rotation of the gear in the second direction opposite to the first direction pushes the plunger into the reservoir a further distance. During the rotation of the gear in each of the first and second directions, the plunger driver does not change its longitudinal position, while the plunger moves longitudinally into the reservoir.

2. The syringe according to claim 1, wherein, The track includes multiple slots.

3. The syringe according to claim 2, wherein, When the gear rotates in the first direction, the pin travels in the first slot of the plurality of slots, and when the gear rotates in the second direction, the pin travels in the second slot of the plurality of slots.

4. The syringe according to claim 2, wherein, Each slot in the slot includes a straight section, a cam section, and an end point.

5. The syringe according to claim 2, wherein, The track and the plurality of slots cut into the inner wall of the plunger.

6. The syringe according to claim 2, wherein, Each of the plurality of slots is separated from the adjacent slot by a partition wall.

7. The syringe according to claim 2, wherein, The plurality of slots form a zigzag pattern in the track.

8. The syringe according to claim 1, wherein, The plunger also includes a bypass rail that communicates with the rail.

9. The syringe according to claim 1, wherein, The plunger also includes a piston with an O-ring.

10. The syringe according to claim 4, wherein, The plunger also includes a piston, and the cam segment is inclined in a direction away from the piston.

11. The syringe according to claim 2, wherein, The track and the plurality of slots cut through the wall of the plunger.

12. A syringe, the syringe comprising: Storage device, the storage device having an output port; A plunger having a track including a plurality of slots, each slot including a straight section, a cam section and an end point, and the plunger being received within a portion of the reservoir; A plunger driver includes a gear connected to one end of a shaft and a pin located near the opposite end of the shaft, the plunger driver being received inside the plunger, wherein the pin is located inside the rail and engages the rail; Thus, when the pin travels in the first slot of the plurality of slots, the rotation of the gear in the first direction advances the plunger into the reservoir a first distance, and when the pin travels in the second slot of the plurality of slots, the rotation of the gear in the second direction, opposite to the first direction, advances the plunger into the reservoir a further distance; and During the rotation of the shaft in each of the first and second directions, the plunger driver does not change its longitudinal position, while the plunger moves longitudinally into the reservoir.

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

14. The syringe according to claim 12, wherein, The track and the plurality of slots cut into the inner wall of the plunger.

15. The syringe according to claim 12, wherein, Each of the plurality of slots is separated from the adjacent slot by a partition wall.

16. The syringe according to claim 12, wherein, The plurality of slots form a zigzag pattern in the track.

17. The syringe according to claim 12, wherein, The plunger also includes a bypass rail that communicates with the rail.

18. The syringe according to claim 12, wherein, The plunger also includes a piston with an O-ring.

19. The syringe according to claim 12, wherein, The plunger also includes a piston, and the cam segment is inclined in a direction away from the piston.

20. The syringe according to claim 12, wherein, The track and the plurality of slots cut through the wall of the plunger.

21. The syringe according to claim 1, wherein, After the pin reaches the end of the slot in the track, the gear continues to rotate in the same direction in either the first or the second direction without further pushing the plunger into the reservoir.

22. The syringe according to claim 21, wherein, The continued rotation causes the plunger to rotate in place within the reservoir.

23. The syringe according to claim 1, wherein, The plunger includes a through-hole, and the shaft includes a through-hole, the through-hole of the shaft being alignable with the through-hole of the plunger to allow the pin to be inserted into the shaft during assembly.

24. The syringe according to claim 4, wherein, The dosing cycle includes over-rotating the gear after the pin reaches the end of one of the plurality of slots to ensure that the pin reaches the end.

25. The syringe according to claim 8, wherein, The bypass track includes a pin entry point configured to receive the pin during assembly, and a pin rest point located at the beginning of the track.

26. The syringe according to claim 25, wherein, The bypass rail can only be connected at the start of use, and cannot be connected by the pin once the dose delivery begins.

27. The syringe according to claim 25, wherein, If the gear rotates in the wrong direction at the start of dosing, the pin will be driven into the pin rest point, causing the plunger to rotate in place without a dose being dispensed, until the gear rotates in the opposite direction.

28. The syringe according to claim 12, wherein, After the pin reaches the end of one of the slots in the track, the gear continues to rotate in the same direction in the first and second directions without further pushing the plunger into the reservoir.

29. The syringe according to claim 28, wherein, The continued rotation causes the plunger to rotate in place within the reservoir.

30. The syringe according to claim 12, wherein, The dosing cycle includes over-rotating the gear after the pin reaches the end of one of the plurality of slots to ensure that the pin reaches the end.

31. The syringe according to claim 12, wherein, The plunger includes a through-hole, and the shaft includes a through-hole, the through-hole of the shaft being alignable with the through-hole of the plunger to allow the pin to be inserted into the shaft during assembly.

32. The syringe according to claim 17, wherein, The bypass track includes a pin entry point configured to receive the pin during assembly, and a pin rest point located at the beginning of the track.

33. The syringe according to claim 32, wherein, (i) The bypass rail can only be accessed at the start of use and cannot be accessed by the pin once the dose delivery has begun; and (ii) if the gear rotates in the wrong direction at the start of dosing, the pin will be driven into the pin rest point, causing the plunger to rotate in place without a dose being dispensed until the rotation of the gear is reversed.

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