# US 11,998,718 B2 · System and method for syringe plunger engagement with an injector

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- Number: US 11,998,718 B2
- Document ID: US11998718B2
- Status: Granted
- Kind: B2
- Application number: 17/999,592
- Filed: 2021-06-16
- Published: 2023-09-14
- Granted: 2024-06-04
- Earliest claimed: 2020-06-18
- Assignees: Bayer HealthCare LLC
- Applicants: Bayer Healthcare LLC
- Inventors: Kevin Cowan; James Dedig; Shahab Taheri; Abhinav Srivastava; Barry Tucker; Michael Swantner; Christopher Capone; Jaroslow Wlodarczyk; Andrew Osan
- Web page: https://patentgrep.com/patent/US11998718B2

## CPC

- A61M 5/14546: {Front-loading type injectors}
- A61M 5/007: {for contrast media}
- A61M 5/14566: {with a replaceable reservoir for receiving a piston rod of the pump}
- A61M 5/31515: {Connection of piston with piston rod}
- A61M 5/365: {Air detectors (A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626)}
- A61M 2005/14553: {comprising a pressure jacket}
- A61M 2205/502: User interfaces, e.g. screens or keyboards
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}

## Abstract

A plunger for use with a syringe includes a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end. The plunger further includes at least one retaining member associated with and extending proximally from the plunger body. The at least one retaining member has a first end connected to the plunger body, a second end proximal to the first end and radially and resiliently deflectable relative to the first end, and at least one catch on the second end. A fluid injector system includes a piston having a plunger engagement mechanism configured for interacting with the at least one retaining element of the plunger to releasably engage the plunger for reciprocally driving the plunger within a barrel of the syringe.

## Claims

### Claim 1

A plunger for use with a syringe, the plunger comprising:
a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end; and
at least one retaining member associated with and extending proximally from the plunger body, the at least one retaining member comprising:
a first end connected to the plunger body;
a second end proximal to the first end and radially and resiliently deflectable relative to the first end; and
at least one catch on the second end,
wherein the at least one retaining member has an outer surface configured to engage a plunger engagement sleeve of a plunger engagement mechanism on a piston of a fluid injector system when the plunger is in a locked state with the piston,
wherein the at least one retaining member has an inner surface configured to engage a plunger engagement post of the plunger engagement mechanism when the plunger is in the locked state with the piston,
wherein the at least one catch is configured to fixedly engage a locking feature on one of the plunger engagement sleeve and the plunger engagement post when the plunger is in the locked state with the piston to prevent axial movement of the plunger relative to the piston,
wherein the at least one catch has a first rounded or angled proximal surface at a proximal end of the at least one catch for flexibly engaging a distal end of the locking feature on one of the plunger engagement sleeve and the plunger engagement post during engagement of the plunger to the piston, and a second rounded or angled distal surface at a distal end of the at least one catch for flexibly engaging a proximal end of the locking feature on one of the plunger engagement sleeve and the plunger engagement post during disengagement of the plunger from the piston; and
wherein in an unlocked state of the plunger engagement mechanism the first rounded proximal surface and the second rounded distal surface of the at least one catch are configured to radially deflect the second end of the at least one retaining member upon axial movement of the piston relative to the plunger due to a flexing interaction of the at least one catch with the locking feature on one of the plunger engagement sleeve and the plunger engagement post.

### Claim 2 (depends on 1)

The plunger according to claim 1, wherein the at least one retaining member comprises a plurality of retaining members spaced apart around the central longitudinal axis.

### Claim 3 (depends on 1)

The plunger according to claim 1, wherein the at least one retaining member extends proximally in a direction parallel with the central longitudinal axis.

### Claim 4 (depends on 1)

The plunger according to claim 1, wherein the plunger is configured to engage the plunger engagement mechanism regardless of angular orientation of the plunger relative to the piston of the fluid injector system.

### Claim 5 (depends on 1)

The plunger according to claim 1, wherein the at least one catch protrudes radially inward from the inner surface of the at least one retaining member in a direction toward the central longitudinal axis.

### Claim 6 (depends on 1)

The plunger according to claim 1, wherein the at least one catch protrudes radially outward from the outer surface of the at least one retaining member in a direction away from the central longitudinal axis.

### Claim 7 (depends on 1)

The plunger according to claim 1, wherein the at least one catch defines a locking recess for receiving at least a portion of the plunger engagement mechanism when the plunger is connected to the piston.

### Claim 8 (depends on 1)

The plunger according to claim 1, wherein the at least one catch protrudes radially inward from the inner surface of the at least one retaining member in a direction toward the central longitudinal axis, and wherein the at least one catch is configured to be received within the locking feature that is shaped as a locking groove protruding radially inward from an outer surface of the plunger engagement post when the plunger is in the locked state with the piston.

### Claim 9 (depends on 1)

The plunger according to claim 1, wherein the plunger body has conical-shaped portion at the distal end and a cylindrical-shaped portion at the proximal end.

### Claim 10 (depends on 9)

The plunger according to claim 9, wherein the at least one retaining member protrudes proximally from an inner surface of the conical-shaped portion.

### Claim 11 (depends on 10)

The plunger according to claim 10, further comprising a plurality of release tabs protruding radially inward from an inner surface of the cylindrical-shaped portion or proximally from the inner surface of the cylindrical-shaped portion, each of the plurality of release tabs configured for interacting with the plunger engagement sleeve to effect a release of the plunger from the piston upon rotation of the plunger about the central longitudinal axis.

### Claim 12 (depends on 11)

The plunger according to claim 11, wherein a proximal end of each of the plurality of release tabs has a pointed guide surface.

### Claim 13 (depends on 1)

The plunger according to claim 1, wherein when the plunger is in the locked state with the piston, the at least one catch protrudes radially outward from the outer surface of the at least one retaining member in a direction away from the central longitudinal axis, and wherein the at least one catch is configured to be received within the locking feature that is shaped as a locking groove protruding radially outward form an inner surface of the plunger engagement sleeve.