Patent Application
20150292495
The embodiments described below relate to liquid metering, and more particularly, to an improved syringe quick disconnect interface and related methods.
Syringes generally include a plunger assembly that moves within a fluid bore. The plunger can draw in (aspirate) a fluid when the plunger is retracted from the bore and can dispense fluid when the plunger is pushed into the bore. Syringes are known for their precise fluid control and thus, have received great commercial success in the medical and laboratory fields. Typically, a syringe includes a single fluid port, wherein the fluid is drawn into and expelled from the bore through the port.
Although the syringes can be controlled manually, they are often utilized with electronic syringe pumps to provide an automated system. Such pump systems generally utilize a lead screw or ball screw driven by a stepper motor to effectuate precise control of the syringe plunger's position. In the medical field, syringe pumps can provide, for example, automated dosing to a patient, and in laboratory settings they may be used for precise reagent metering. In scientific/industrial settings, such pumps are often employed in chromatography, electrophoresis, hematology, flow cytometry, immunoassays, and even for refilling ink cartridges.
In some situations, the syringe pump can form part of a larger syringe pump manifold system wherein multiple syringes are coupled to the manifold system. Each syringe may include its own pump or a single syringe pump may control multiple syringes. The syringe pump may control the flow of fluid into or out of a syringe. The syringe pump may, in addition, combine fluids from more than one syringe.
In order to provide a fluid-tight coupling between the syringe and the manifold assembly, a separate sealing member is often required. Positioning the separate sealing member while simultaneously attaching the syringe to the manifold assembly is generally difficult. One source of difficulty stems from the syringe being typically inserted into a bottom surface of the manifold or some other syringe accepting port. Consequently, there is no place for the sealing member to rest before coupling the syringe to its corresponding port. Therefore, a user generally attempts to hold the sealing member in place with one hand while coupling the syringe to the manifold with the other. This makes for a difficult task especially if the syringe being coupled is positioned between two other adjacent syringes, resulting in limited space for a user to maneuver.
In other attachment schemes, a Luer fitting is often utilized for fluid connections. Luer connectors (often marked by the name “Luer-Lock”) are used for making leak-free connections between a male-taper fitting of the syringe itself and its mating female portion found on medical and laboratory instruments, such as hypodermic syringe tips/needles or stopcocks. A Luer-Lock requires that the user thread the syringe onto the mating portion. This typically takes two hands to accomplish, and also requires a reasonable amount of space between syringes on a manifold for finger clearance during threading. Similarly, interfaces with ¼-28 UNF-2A threaded ends have the same limitations. Luer-lock fittings requires about half a turn and ¼-28 UNF-2A fittings require up to five turns.
Overall, the assembly process—inserting and removing syringes to and from manifolds/pumps—becomes increasingly difficult with multi-channel units. Often, it is necessary that a syringe be replaced or taken off the pump, but because of the pump's compact design, it is very difficult to remove a syringe that is in the middle of neighboring syringes, as there is insufficient space for a person's fingers to provide clearance so to maintain a proper grip. It is also difficult or at least ill-advised to use a pair of pliers to aid in syringe installation and removal. Besides risking breakage of a syringe, either not enough torque may be applied onto the syringe assembly or too much torque may be applied.
Therefore, there is a need for an apparatus that can simultaneously hold onto the sealing member and the syringe to create a fluid tight junction. Therefore, there is a need for an apparatus that can simultaneously hold onto the sealing member and the syringe to create a fluid tight junction without the need to rotate the syringe for threading. There is a need to alleviate the difficulty of removing a syringe that is bordered by two other syringes when installed on a manifold or pump. There is a need to alleviate the difficulty of re-attaching a syringe onto a pump/manifold. There is a need to provide an apparatus and method to aid in the assembly and dissasembly of syringes into manifolds/pump while providing the proper installation force. There is a need to minimize glass syringe barrel breakage by eliminating the need for users to grab the glass barrel in order to secure to or remove the syringe from the pump valve and/or manifold (when this is done, the glass barrel can break off from the end cap). There is a need for a device that can flex to allow a user to pull the device away from the syringe once the syringe is at least partially coupled to the manifold in order to remove the apparatus without damaging the syringe or removing the sealing member.
The embodiments described below overcome these and other problems and an advance in the art is achieved. The embodiments described below provide an apparatus that can retain a sealing member against a syringe while the syringe is being coupled to a manifold or some other type of port. This allows a user to move the syringe into position to be coupled to the manifold easily. The apparatus further includes deformable members that accommodates a syringe while allowing a user to pull a syringe directly away from the apparatus. Similarly, the apparatus provides the ability to simply press a syringe into place for installation into a pump or manifold.
A fluid metering system having a syringe assembly attachable to a syringe dock is provided according to an embodiment. According to an embodiment a plunger assembly with the syringe assembly has a plunger configured to at least one of aspirate a fluid into the syringe assembly and dispense a fluid contained in the syringe assembly. A driving portion of a syringe drive with the fluid metering system is attachable to the plunger assembly, wherein the driving portion is configured to actuate at least one of dispensing and aspirating of the fluid. A slot with the syringe dock is configured to accept the syringe assembly, and an end cap with the syringe assembly slidingly engages the slot.
A fluid metering system having a syringe assembly attachable to a polymer syringe dock is provided according to an embodiment. According to an embodiment a plunger assembly with the syringe assembly has a plunger configured to at least one of aspirate a fluid into the syringe assembly and dispense a fluid contained in the syringe assembly. A driving portion of a syringe drive with the fluid metering system is attachable to the plunger assembly, wherein the driving portion is configured to actuate at least one of dispensing and aspirating of the fluid. A slot with the syringe dock is configured to accept the syringe assembly. At least one detent with the slot is configured to engage at least one member of the end cap. A polymer end cap with the syringe assembly slidingly engages the slot. A compliant seal is overmolded with the end cap proximate an orifice that passes through the end cap, wherein the seal is configured to fluidly seal the end cap to the syringe dock such that the orifice is in sealed fluid communication with the fluid metering system, wherein an insertion force necessary for the end cap to engage the slot is between approximately 2.5 and approximately 4.5 pounds.
A method of using a fluid metering system having a syringe assembly attachable to a syringe dock is provided according to an embodiment. According to an embodiment the method comprises the steps of: sliding the syringe assembly into the syringe dock such that the syringe assembly engages the syringe dock and fluidly connects the syringe assembly with the fluid metering system; and attaching the plunger assembly to the syringe drive.
According to an aspect, a fluid metering system having a syringe assembly attachable to a syringe dock is provided. According to an embodiment:
Preferably, the end cap comprises PTFE.
Preferably, the syringe dock comprises PEEK.
Preferably, the plunger assembly is attachable to the driving portion of the syringe drive by a magnetic force.
Preferably, the fluid metering system further comprises:
Preferably, the fluid metering system further comprises:
Preferably, the seal comprises perfluoroelastomer.
Preferably, the seal is overmolded with the end cap.
Preferably, the seal is an o-ring.
Preferably, the fluid metering system further comprises at least one detent with the slot configured to engage at least one member, of the end cap.
Preferably, an insertion force necessary for the end cap to engage the slot is between approximately 2.5 and approximately 4.5 pounds.
Preferably, an insertion force necessary for the end cap to engage the slot is approximately 3.4 pounds.
Preferably, the end cap comprises:
Preferably, the fluid metering system further comprises:
Preferably, the fluid metering system further comprises a radiused ramp that connects the intermediary region to the first member.
According to an aspect, a fluid metering system having a syringe assembly attachable to a polymer syringe dock is provided. According to an embodiment:
Preferably, an insertion force necessary for the end cap to engage the slot is approximately 3.4 pounds.
Preferably, the end cap comprises:
Preferably, the fluid metering system has a first diameter of the first member that is greater than a diameter of the intermediary region; and a second diameter of the second member that is greater than the diameter of the intermediary region.
According to an aspect, a method of using a fluid metering system having a syringe assembly attachable to a syringe dock is provided. The method comprises the steps of:
Preferably, the plunger assembly is configured to at least one of aspirate a fluid into the syringe assembly and dispense a fluid contained in the syringe assembly, and wherein the syringe drive is configured actuate the plunger assembly to at least one of dispense and aspirate a fluid.
Preferably, the step of sliding the syringe assembly into the syringe dock comprises fluidly connecting the syringe assembly with the fluid metering system and attaching the plunger assembly to the syringe drive substantially simultaneously.
Preferably, the syringe dock comprises a slot configured to accept the syringe assembly; an end cap with the syringe assembly is configured to slidingly engage the slot; and wherein the step of pressing the syringe assembly into the syringe dock comprises the step of engaging a detent of the syringe dock with the end cap.
Preferably, the step of attaching the plunger assembly to the syringe drive comprises magnetically attaching the plunger assembly to the syringe drive.
Preferably, the step of attaching the plunger assembly to the syringe drive comprises passing a boss with the driving portion of the syringe drive through a through hole with the plunger assembly.
Preferably, the step of sliding the syringe assembly into the syringe dock comprises encountering an insertion force resistance between approximately 2.5 and approximately 4.5 pounds
Preferably, the step of sliding the syringe assembly into the syringe dock comprises encountering an insertion force resistance is approximately 3.4 pounds.
Preferably, the end cap comprises:
Preferably, the end cap comprises:
Preferably, a first diameter of the first member is greater than a diameter of the intermediary region; and a second diameter of the second member is greater than the diameter of the intermediary region.
The same reference number represents the same element on all drawings. The drawings are not necessarily to scale.
With initial reference to
Turning to
By way of example, a user would, as illustrated in
In an alternate embodiment illustrated by
With reference to
The precision design of the end cap 106 contours shown in
In an example of a calculation used to design an embodiment of the end cap 106, compressive forces Fcomp1, Fcomp2 and Fcomp3 are calculated (see below). With reference to
Equation number 1 is used to calculate frictional force:
F
friction
=μ*F
comp (1)
Where:
Ffriction=frictional force
μ=coefficient of friction
Fcomp=compressive force
The example materials analyzed comprise Teflon PTFE, FKM, and PEEK. The static coefficient of friction is 0.24 for FKM and 0.14 for PTFE and PEEK.
Ffriction1=μ*Fcomp1
Ffriction1=0.24*10 pounds=2.4 pounds
Similarly, the equation for calculating the frictional force due to the Teflon first member 402 engaging the first member bearing surface 602 of the slot 208 as the first member 402 engages the PEEK dock 200 ledge is:
Ffriction2=μ*Fcomp2
Ffriction2=0.14*10 pounds=1.4 pounds
The equation for calculating the frictional force due to the Teflon second member 404 along its outermost diameter to the PEEK dock's 200 detent 604 is:
Ffriction3=μ*Fcomp3
Ffriction3=0.14*6.5 pounds=0.91 pounds
These are merely examples of calculations performed for an embodiment, and in no way should limit the scope of claims or this specification. In another example, more complex Monte Carlo analyses may be performed to aid in defining the appropriate dimensions for both the end cap 106 and slot 208 (and their various members, contours, ramps, undercuts, bosses, detents, etc.). In an example, the modulus of PEEK and PTFE as well as the coefficient of friction for FKM and PEEK/PTFE are known constants. Manufacturing tolerances and run-outs are known, and the dimensions of all portions of the both the end cap 106 and slot 208 are known.
Intermediate calculations, such as those noted for stress-strain (below) and frictional force (above), may be employed to calculate seal 108 stretch, detent 604 compression friction force, post-stretch seal 108 thickness, general compression forces, seal 108 friction force, and slot 208 friction forces. Another equation (Equation number 2, below) may be used to calculate stress or strain, for example:
σ=E*ε (2)
Where:
σ=stress
ε=strain
E=Elastic modulus (psi)
The Elastic modulus is known for materials used, such as for PEEK or PTFE:
EPEEK=500,000 psi
EPTFE=87,000 psi
For example, this equation may be used to determine the stress, σ, imparted, on the Teflon body.
Finally, Monte Carlo analysis may yield the theoretical insertion force for the end cap 106 into the slot 208 based upon the above inputted variables and intermediate calculations. Additionally, compression, clearance, seal 108 volume, orifice 400 runout, and front-to-front and side-to-side float of the end cap 106 while installed in the slot 208 may also be calculated. In one embodiment, the insertion force is under 10 lbs. In one embodiment, the insertion force is between 1.5 and 5.5 lbs. In another embodiment, the insertion force is between 2.5 and 4.5 lbs. In a preferred embodiment, the insertion force is approximately 3.4 lbs. These ranges are examples, and do not serve to limit the scope of the claims in any way.
It will be clear to one skilled in the art that adjusting the dimensions of at least one of the first member 402, second member 404, intermediary region 406, ramp 408, first end 410, and/or second end 412, as well as adjusting the material from which the end cap 106 is made will change the insertion force. Similarly, adjusting the dimensions of at least one of the seal-bearing surface 600, first member bearing surface 602, the slot 208 in general, and/or the detent 604 as well as adjusting the material from which the syringe dock 200 is made will change the insertion force.
The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the invention. Indeed, persons skilled in the art will recognize that certain elements of the above-described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the invention. It will also be apparent to those of ordinary skill in the art that the above-described embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the invention.
Thus, although specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. The teachings provided herein can be applied to other devices and method, and not just to the embodiments described above and shown in the accompanying figures. Accordingly, the scope of the invention should be determined from the following claims.
