US20050196287A1 - Flexible sleeve syringe and system - Google Patents

Abstract

A syringe having an elastic sleeve which defines a fluid chamber, and a plunger positioned within the elastic sleeve. The outer diameter of the plunger is greater than the inner diameter of the elastic sleeve such that the plunger elastically deforms the sleeve during use. A syringe pump system is also provided.

Description

RELATED APPLICATIONS
• This application claims priority from U.S. Provisional Patent Application No. 60/516,459 which was filed on Nov. 3, 2003, and is incorporated herein by way of reference.
TECHNICAL FIELD
• The present invention relates to syringes and, more particularly, to syringes having flexible components, including a flexible sleeve, that are adapted to maintain sealing and performance integrity under varying chemical, temperature, fatigue and pressure conditions.
BACKGROUND OF THE INVENTION
• Syringes have long been used in various applications requiring precise, sterile or convenient pumping, extraction or delivery of liquids. As a result, many varieties of syringes exist in different forms suitable for different purposes.
• In environments requiring precision and sterile handling of liquids for medical or industrial applications, it is necessary for syringes and their components to have high temperature and chemical resistance. Such applications may require high volume, continuous operation which, therefore, calls for designs and components capable of high cycle or fatigue resistance.
• It is known to use syringes or syringe pumps having a glass sleeve and a PTFE (polytetrafluoroethylene) plunger, in which both materials are selected for their inert properties and high chemical and temperature resistance. A problem associated with such designs, however, is tendency for the PTFE plunger to set, particularly after a high number of cycles. The setting of the plunger, as a result of compressive forces from the liquid pumped and the rigid glass sleeve during use, causes leakage between the plunger and the sleeve.
• One known solution to the problems associated with glass and PTFE systems is to over-size the PTFE plunger so that it is under greater compressive force when installed in the glass sleeve. This solution has drawbacks in that the onset of leakage is merely prolonged and the syringe will require more axial force to pump the liquid. The requirement of more axial force will subject associated components to greater wear and higher costs in design to handle the increased load. In situations where pumping through the syringe is continuous or high volume, the need for increased axial force will increase power input requirements and associated costs.
SUMMARY OF THE PRESENT INVENTION
• Some embodiments of the present invention provide a syringe or syringe pump system that has superior resistance to leakage, chemicals, and heat, such as in high volume or continuous cycle environments, while also having low pumping force requirements.
• The present invention is directed to a syringe and syringe pump system having a plunger and an elastic sleeve, wherein the sleeve and plunger are sized such that the outside diameter of the plunger is greater than the inside diameter of the sleeve, thereby causing elastic deformation of the sleeve during use.
• One embodiment of the present invention provides a syringe, comprising an elastic sleeve defining a fluid chamber, and a plunger positioned within the elastic sleeve, wherein the outer diameter of the plunger is greater than the inner diameter of the elastic sleeve such that the plunger elastically deforms the sleeve during use. The elastic sleeve may comprise a syringe sleeve and a surrounding sleeve, wherein the fluid chamber is defined by the interior of the syringe sleeve and the syringe sleeve is positioned within the interior of the surrounding sleeve. The surrounding sleeve may comprise an elastomeric material which provides a compressive force against the outer surface of the syringe sleeve upon deformation of the sleeve during use. The syringe sleeve may comprise a semi-rigid thermoplastic material, such as a fluoroplastic chosen from the groups consisting of: PTFE, PFA and FEP. The surrounding sleeve may comprise, for example, silicone.
• The syringe may further comprise a housing which encloses the elastic sleeve. The housing may include a first end cap located at the proximal end of the syringe sleeve, a second end cap positioned at the distal end of the syringe sleeve, and at least one sidewall extending between the end caps (e.g., a hollow tube secured to the first and second end caps such that an annular space is provided between the tube and the elastic sleeve). The syringe may further comprise a rod which extends distally away from away from the plunger, and the first end cap may include an opening through which the rod extends. The second end cap may include at least one fluid passageway in fluid communication with the fluid chamber. The proximal end of the second end cap may include a chamber, and an insert member configured for insertion into the chamber of the second end cap may also be provided. The distal end of the elastic sleeve may be secured within the chamber between the wall of the chamber and the insert member.
• Another embodiment of the present invention provides a syringe pump system. This syringe pump system may include an elastic sleeve defining a fluid chamber, a plunger positioned within the elastic sleeve, wherein the outer diameter of the plunger is greater than the inner diameter of the elastic sleeve such that the plunger elastically deforms the sleeve during use, an intake conduit having a first check valve associated therewith and in fluid communication with the fluid chamber, and an output conduit having a second check valve associated therewith and in fluid communication with the fluid chamber. Fluid may be drawn into the syringe pump through the intake conduit and the first check valve, and thereafter expelled from the syringe pump through the output conduit and the second check valve upon reciprocation of the plunger.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic, partially cross-sectional illustration of a syringe system according to one embodiment of the present invention;
• FIG. 2 is a schematic, partially cross-sectional illustration of a syringe according to one embodiment of the present invention;
• FIG. 3 is a schematic, cross-sectional, exploded illustration of the distal end cap and insert member of the syringe shown inFIG. 2; and
• FIG. 4 is a schematic, cross-sectional illustration of the proximal end cap of the syringe shown inFIG. 2; and
• FIG. 5 is a schematic, partially cross-sectional illustration of a plunger which may be used in an embodiment of the present invention.
DETAILED DESCRIPTION
• Embodiments of the present invention provides syringes and syringe systems which provide reduced friction between the plunger and the wall of the fluid chamber, reduced wear on components such as the plunger, and/or simplified manufacturing due to an ability to compensate for misalignment and less stringent tolerances. With respect to the reduced friction feature, embodiments of the present invention have lower pumping force requirements. Thus, for example, when a syringe according to an embodiment of the present invention is motor driven (i.e., a motor causes reciprocal movement of the plunger), less power is needed. In fact, this can allow a single motor to drive multiple syringes.
• According to embodiments of the present invention, a syringe is provided comprising an elastic sleeve defining the fluid chamber of the syringe, and a plunger positioned within the elastic sleeve. The outer diameter of the plunger is oversized (i.e., greater than the inner diameter of the elastic sleeve) such that the plunger (in particular, the distal head portion of the plunger) will elastically deform the sleeve during use. As used herein, this elastic deformation simply means that the portion of the elastic sleeve which is adjacent the plunger at any given time is forced outward—thus creating a bulge in the wall of the elastic sleeve at the location of the plunger (seeFIG. 2). However, because this deformation is elastic, as the plunger is moved axially away from the deformed region of the sleeve and thus no longer applies an outward force against the interior wall of the sleeve, the deformed region of the elastic sleeve will return to its original size and shape. Oversizing the plunger in this manner will also reduce the risk of leakage (the interior walls of the elastic sleeve will essentially mold to the outer surface of the plunger). Furthermore, the materials used for the plunger and at least the portion of the elastic sleeve forming the wall of the fluid chamber in some embodiments comprise materials having low coefficients of friction (e.g., fluoroplastics), thus providing the friction reductions mentioned above even though the plunger is oversized.
• In some embodiments, in order to provide desired properties such as chemical resistance and inertness, low coefficient of friction, reduced wear, and high temperature resistance for the portion of the sleeve providing the fluid chamber of the syringe, while also ensuring that the sleeve is elastic (i.e., resumes its original shape when not being deformed by the plunger), the elastic sleeve may be formed from two or more layers of materials having distinct properties. For example, the elastic sleeve may comprise at least one semi-rigid sleeve member positioned within at least one elastomeric sleeve member (i.e., concentric to one another) such that, upon deformation of the at least one semi-rigid sleeve member, the at least one elastomeric sleeve member will provide a restoring force against the semi-rigid sleeve member such that it is returned to its original size and shape. The term “semi-rigid” simply means that the sleeve may be readily deformed by the plunger (due to the over-sizing of the plunger), but a deformed portion of the sleeve would not fully return to its original shape without the application of a restoring force. In one particular embodiment of the present invention (e.g.,FIGS. 1 and 2) a semi-rigid syringe sleeve is surrounded by an elastomeric surrounding sleeve (with the surrounding sleeve sized to fit snugly over the syringe sleeve). The elastomeric surrounding sleeve provides the necessary restoring force since it is deformed with the syringe sleeve yet has the necessary elastic properties to force the syringe sleeve back to its orginal shape.
• Asyringe system10 according to one embodiment of the present invention is diagrammatically shown in partial cross-section inFIG. 1. Aplunger12 having arod14 which may be attached to the plunger or formed integrally therewith is movably coupled to adrive system16 of any one of the type generally known to those skilled in the art in order to impart linear, reciprocal motion to theplunger12 as indicated by thearrow18. In the embodiment ofFIG. 1,plunger12 has a round profile when viewed from the top (not shown), though it could vary among a variety of geometrical configurations (see, e.g.,FIG. 5).
• Asyringe sleeve20 is shaped cylindrically to cooperate in sealing engagement with theplunger12 which is positioned therein. However,sleeve20 may be configured in any geometrical shape that cooperates with theplunger12 for sealing engagement, though in the embodiment shown it has a round cross-section. The lateral dimension or inner diameter of thesleeve20 is smaller than the lateral dimension or outer diameter of theplunger12 in order to provide a compressive fit when theplunger12 is positioned inside thesleeve20.
• By way of example, theplunger12, may be made from a variety of materials such as PCTFE (polychlorotrifluoroethylene, e.g., Kel-F®) or another suitable plastic with similar properties relating to chemical. temperature and fatigue resistance, as well as resiliency, impermeability, and chemical inertness (e.g., other fluoroplastics). While a more rigid material may be used forplunger12, including glass or metal, such rigid materials would cause greater wear on thesleeve20. The selection of a fluoroplastic such as PCTFE provides an appropriate balance of strength, smoothness and limited elasticity. Depending on a particular application and its parameters, as well as the selection of material and dimension for thesleeve20, another material may be selected forplunger12, such as various thermoplastics (e.g., fluoroplastics such as PTFE, FEP, or PFA. As is known to those skilled in the art, it may also be desirable to avoid the use of an indentical material forplunger12 andsleeve20.
• By way of example, thesleeve20 may be made from PTFE (Teflon®, for example) or another fluoroplastic, as fluoroplastics have high chemical and temperature resistance in addition to some elasticity. Fluoroplastics also have extremely low coefficients of friction—an advantageous property since, among other things, it will reduce the force required to reciprocate the plunger. Other suitable fluoroplastics include PFA (perfluoroalkoxy resin), and FEP.Sleeve20 can comprise an extruded, thin-walled polymer tube.
• The combination of materials used for thesleeve20 andplunger12 provides minimal frictional resistance in combination with sufficient sealing capability during pumping of a liquid.
• Thesyringe chamber22 is in fluid communication with anintake conduit24 having acheck valve26, and anoutput conduit28 having a check valve30 (such fluid communication may be provided withinend cap36 described further herein). Of course any number and type of fluid outlets, conduits, valves, and connector elements may be provided. For example, the check valves could be replaced by one or more multi-port selection valves (e.g., a rotary selection valve), thus providing a syringe system for selectively delivering and/or extracting fluid by operation of the selection valve(s) and a drive system which reciprocates the plunger. In the embodiment shown inFIG. 1, thesyringe system10 is essentially a positive displacement pump which is operated merely by reciprocating plunger12 (e.g., manually or using adrive system16 which causes reciprocal movement ofplunger rod14 and henceplunger12 withinsyringe sleeve20.
• As also shown inFIG. 1, asilicone sleeve32 surrounds thesyringe sleeve20. Of course silicone is merely exemplary, as other elastomeric materials with sufficient elasticity and restoring energy for restoringsyringe sleeve20 may be used for the surroundingsleeve32. A housing comprises alower end cap34, having anopening36 and seals38 for therod14 and other components; anupper end cap36 cooperating withvarious seals38 as shown; and a set ofsidewalls40. Thesidewalls40 may comprise of any number such as four, that encloses the other components and supports the end caps34 and36 or a single cylindrical sidewall (not shown) may be used. Theseals38 may be O-rings or other seals, including seal assemblies of the type known to those skilled in the art. The various components may also be affixed to one another using and adhesive (e.g., an epoxy glue), heat welding, ultrasonic welding, snap-fitttin, or other suitable means known to those skilled in the art. Thegap42 between the sidewalls40 and thesilicone sleeve32 may be filed with a compressible medium such as, but not limited to, gel, liquid, air, or foam, in order to provide additional support to the surroundingsleeve32 and thesyringe sleeve20. Thedrive mechanism16 may have any one of various types of internal gearing such as rack and pinion and it may be adapted to simultaneously drive two or more syringe pumps made in accordance with the present invention and mounted to a bench or freestanding work station.
• FIGS. 2-4 depict another embodiment of asyringe110 according to the present invention.Syringe110 once again includes afluid chamber122 defined by the interior of a flexible sleeve which is elastically deformed byplunger112 during use (i.e., asplunger112 moves in either or both of the directions indicated by arrow118).
• Plunger112 can have any of a variety of shapes and configurations, and that shown inFIG. 2 is merely exemplary.FIG. 5 depicts an alternative embodiment for aplunger212 and aplunger rod214 attached thereto.Plunger112 can be made from any of a variety of materials, particularly thermoplastics such as fluoroplastics. Exemplary materials include PTFE, PCTFE (e.g., Kel-F®), FEP and PFA.
• As also seen inFIG. 2, aplunger rod114 is attached to, and extends away from the proximal end ofplunger112.Plunger rod114 may once again be attached to anysuitable drive system116, or may even be configured for manual use (e.g., by providing a handle or other device at the proximal end ofplunger rod114 in order to facilitate manual use of syringe110).Plunger rod114 may be made from any of a variety of materials, particularly rigid materials such as stainless steel.
• Syringe110 shown inFIG. 2 also includes a flexible, elastic sleeve which is elastically deformed byplunger112, as shown inFIG. 2. (It should be noted that the thickness of the elastic sleeve components and theouter housing140 inFIG. 2 have been exaggerated to more clearly depict the deformation of the elastic sleeve). The outer diameter ofplunger112 is greater than the inner diameter of the flexible sleeve ofsyringe110 such thatplunger112 will urge the adjacent region of the elastic sleeve outwardly. Thus, the flexible sleeve will bulge outwardly in the regionadjacent plunger112, and the bulge thus created will travel along the sleeve asplunger12 is moved in the directions shown byarrow118. As the plunger moves away from a deformed region of the elastic sleeve, that region will return to its original size and shape, this ensuring a fluid tight fit between the plunger and the elastic sleeve even after repeated use of the syringe. While the elastic sleeve ofsyringe110 may comprise a single, sleeve element, the embodiment ofFIG. 2 once again includes a pair of sleeves which provide the elastic sleeve member ofsyringe110.
• In particular,syringe110 includes asyringe sleeve120 and anelastomeric surrounding sleeve132 which surroundssyringe sleeve120.Syringe sleeve120 may be made from a thermoplastic material, such as a fluoroplastic. Exemplary materials include PTFE, FEP and PFA, all of which provide reduced friction, thereby minimizing the force needed to moveplunger112, as well as chemical resistance and inertness. The material used forsyringe sleeve120 may also provide asleeve120 which is semi-rigid so thatsleeve120 may be deformed byplunger112, as shown. In the embodiment shown,syringe sleeve120 is not itself formed from an elastomeric material, since elastomers tend to have less chemical resistance than thermoplastics such as PTFE, FEP or PFA. It should be pointed out that fluoroplastics (e.g., PTFE, FEP and PFA) and the like do have some elasticity, particularly when extruded into a thin-walled tube which is then deformed in the manner shown inFIG. 2. However, these materials will take a set (due to creep or cold flow)—meaning that they will not fully return to their original size and shape without the application of a restoring force. Therefore, in order to ensure that the walls ofsyringe sleeve120 return to their original inside diameter after passage ofplunger112,elastomeric sleeve132 surroundssyringe sleeve120 such thatelastomeric sleeve132 will urgesyringe sleeve120 back to its original size and shape.Elastomeric sleeve132 will be deformed in the regionadjacent plunger112, as shown, since it is formed from an elastomer. However, the deformed region ofelastomeric sleeve132 will return to its original shape onceplunger112 has moved to a new location (i.e.,plunger112 is no longer applying an outward force to the previously-deformed region). Because of this,sleeve132 will also urgesyringe sleeve120 back to its original size and shape, thus ensuring a fluid-tight fit betweenplunger112 andsyringe sleeve120, even after repeated use.
• Syringe110 shown inFIGS. 2-4 also includes a pair of end caps, namely proximal (or first)end cap134 and distal (or second)end cap136.Syringe sleeve120 extends betweenend caps134 and136, as shown.Plunger rod114 extends through acentral bore135 provided onproximal end cap134, as shown inFIGS. 2 and 4. However, in this embodiment,central bore135 is approximately equivalent in size to the outer diameter ofsyringe sleeve120 such thatplunger rod114 will not contact bore135 ofproximal end cap134. In this manner,plunger rod114 is free to float with respect toproximal end cap134. This not only simplifies manufacturing and assembly, but also eliminates the need for precise alignment ofplunger rod114 anddrive system116. In addition, this arrangement also reduces the force required to reciprocateplunger112 since there is no frictional contact betweenplunger rod114 and any component ofsyringe110.
• As best seen inFIG. 4,proximal end cap134 essentially comprises a cylindrical ring having a shoulder147 extending around the outer circumference thereof. As further discussed herein, the size (or depth) of shoulder147 may be approximately equivalent to the wall thickness of outer sidewall (or tube)140, such thatouter tube140 may be secured toproximal end cap134 and abut against shoulder147, thus providing a smooth transition betweenend cap134 and outer tube140 (seeFIG. 2). As also seen inFIG. 2, the proximal end ofsyringe sleeve120 may be secured to the interior wall ofend cap134, such as by use of an adhesive, heat welding, ultrasonic welding, snap fitting, or other known or suitable attachment means. However, in some embodiments, it may not be necessary to attachsyringe sleeve120 to endcap134.Tube140 may similarly be attached to the end caps by means of an adhesive (e.g., epoxy), heat welding, ultrasonic welding, snap fitting, or other known or suitable attachment means.
• Syringe110 also includes adistal end cap136, as best seen inFIGS. 2 and 3. Likeend cap134,distal end cap136 can be made from any of a variety of materials, particularly various types of thermoplastics. In the embodiment ofFIG. 2, there is generally no fluid contact withend caps134 and136. Therefore, chemical resistance is not as significant of a factor with respect to these two components. One suitable material forend caps134 and136 is PEEK.
• As best seen inFIG. 3,distal end cap136 includes a hollow,cylindrical body137 and aconnection member139 extending away from the distal end ofbody member137. In the embodiment shown,connection member139 merely comprises a hollow cylinder having a central passageway (or bore)146 extending therethrough. However,connection member139 may have any of a variety of shapes and configurations, and may be configured in order to facilitate attachment of the syringe to a variety of devices. For example,connection member139 may alternatively comprise a male or female-threaded connector, a Luer connector, or any of a variety of other connecting elements known to those skilled in the art. A quick disconnect fitting may also be attached at the distal end ofconnection member139 in order to facilitate attachment ofsyringe110 to a valve structure, or other apparatus or device. It is even contemplated that a hypodermic needle may be attached to connection member139 (particularly whenconnection member139 comprises a Luer connector), thus allowing the syringe to be used for the injection or withdrawal of fluids from a patient and other similar uses.
• Likeend cap134,cylindrical body137 ofdistal end cap136 includes a shoulder (or flange)143 which extends about the outer circumference ofbody137. Once again the depth ofshoulder143 may be approximately the same as the wall thickness ofouter tube140, andouter tube140 may be attached to endcap136 such that the distal end ofouter tube140 abuts againstshoulder143, as shown.Outer tube140 may be attached to endcap136 in the same manner as described previously.
• As mentioned previously,cylindrical body member137 is generally hollow in nature, thus providing achamber145 at the proximal end ofend cap136. The distal end ofsyringe sleeve120 may be inserted intochamber145. In order to ensure a fluid-tight connection betweensyringe sleeve120 andend cap136, aninsert member150 is also provided.Insert150 includes a first cylindrical portion151 and a secondcylindrical portion152 extending away from thedistal end wall153 of first cylindrical portion151. Abore155 extends through both first and secondcylindrical portions151 and152. During assembly, the distal end ofsyringe sleeve120 is inserted intochamber145 ofbody member137 ofdistal end cap136, and thereafter insert150 is inserted intochamber145 such that secondcylindrical portion152 extends throughbore146 onend cap136 and first cylindrical portion151 is positioned withinchamber145. The distal end wall ofsilicone sleeve120 will thus be positioned withinchamber145, between the outer circumferential surface of first cylindrical portion151 ofinsert150 and the interior sidewall ofchamber145. In addition,chamber145 and insert150 may be sized and configured such that distal end wall ofsyringe sleeve120 will be compressed betweenchamber145 and the outer circumferential surface of first cylindrical portion151 ofinsert150 in order to securesyringe sleeve120 to endcap136.
• In the embodiment shown inFIG. 3, a ridge144 extends around the inner circumference of the proximal end ofchamber145 ofend cap136. The distal end ofsyringe sleeve120 is folded outwardly down over the outer surface ofsyringe sleeve120, as best seen inFIG. 2. The folded portion ofsyringe sleeve120 is positioned within the interior ofbody portion137, distally of ridge144. The height of ridge144 is such that once the distal end ofsleeve120 is inserted intoend cap136 and insert150 has been secured to endcap136 as shown inFIG. 2, ridge144 will ensure that the distal end ofsyringe sleeve120 remains within the interior ofend cap136, secured betweeninsert150 and the interior sidewall ofchamber145. In fact, onceinsert150 has been secured to endcap136, it may not be necessary to bond or otherwisesecure syringe sleeve120 to eitherend cap136 or insert150. For example,insert member150 may be press or snap-fit into end cap136 (e.g., by appropriate sizing ofcylindrical portion152 with respect to bore146 onend cap136. Alternatively,insert member150 may be adhesively bonded to endcap136 or attached via heat welding, ultrasonic welding, or other attachment means. It is also contemplated thatinsert member150,end cap136 and the distal end portion ofsyringe sleeve120 may be attached to one another in the same manner (e.g., by use of an adhesive applied withinchamber145 and, if desired withinbore146.
• Sinceinsert150 will be in fluid contact, it will often be desirable to manufacturer insert150 from a chemically-resistant and inert material. Such materials include any of a variety of thermoplastics, such as fluoroplastics, including PTFE, FEP, PCTFE or PFA.
• As mentioned previously,syringe110 also includes anouter tube140.Outer tube140 may simply comprise a clear plastic tube, and is principally intended to protect the flexible sleeve and plunger components ofsyringe110 and provide an aesthetically pleasing appearance. Visible indicia may be provided ontube150 in order to facilitate use ofsyringe110, such as measurement lines imprinted on or molded intotube140. Since the materials used to manufacturer the flexible sleeve components (i.e.,syringe sleeve120 and elastomeric sleeve130) will often not provide a clear view offluid chamber122 and the position ofplunger112, measurement lines and the like may not necessarily provide a precise indication of fluid volume withinsyringe110. However, the bulge in the flexible sleeve caused byplunger112 will generally be visible throughtube140. One exemplary material fortube140 is commercial grade acrylic resin, however, any of a variety of materials may be employed.
• As also seen inFIG. 2,elastomeric sleeve132 is shorter in length thansyringe sleeve120. In fact, once assembled,elastomeric sleeve132 encirclessyringe sleeve120 and only extends betweenend caps134 and136.Elastomeric sleeve132 may be made from any of a variety of elastomeric materials. In general, the composition and wall thickness ofelastomeric sleeve132 should be such that it provides sufficient compressive force against the exterior wall ofsyringe sleeve120 in order to returnsyringe sleeve120 to its original size and shape after passage of plunger112 (i.e., to return a deformed region ofsleeve120 to its original size and shape once that deformed region is no long adjacent plunger112). One particularly suitable material is silicone. In general, the inner diameter ofelastomeric sleeve132 may be equal to or slightly less than the outer diameter ofsyringe sleeve120, thus not only ensuring thatelastomeric sleeve132 remains in place on syringe sleeve120 (provides a snug fit), but also ensuring thatelastomeric sleeve132 will be able to fully restoresyringe sleeve120 to its original size and shape in regions to whichplunger112 is not adjacent.
• As with the previous embodiment, the outer diameter of plunger112 (defined as the maximum outer diameter of any portion of the plunger, particularly when non-cylindrical plungers such asplunger212 inFIG. 5 are employed) is greater than the interior diameter ofsyringe sleeve120. The difference in diameter should be sufficient to ensure a fluid-tight seal between the plunger and the syringe sleeve, to cause deformation of the syringe sleeve wall adjacent the location of the plunger, and allow the plunger to freely slide within the syringe sleeve with minimal force. In one exemplary embodiment, and by way of example only, aPTFE plunger112 having an outer diameter of 0.578 inches may be employed with a cylindrical syringe sleeve made from FEP having an inner diameter of 0.575 inches and a wall thickness of 0.012 inches. In such an embodiment, the elastomeric sleeve may be a cylindrical silicone sleeve having an inner diameter of 0.599 inches and a wall thickness of 0.015 inches.
• In some embodiments of the present invention, the elastic sleeve may be formed from one or more thin-walled tubes. In the case of the syringe sleeve, it may comprise an extruded, thin-walled thermoplastic tube, such as a fluoroplastic tube (e.g., PTFEF, FEP or PFA). By way of example, the wall thickness for the syringe sleeve may be between about 0.008 and about 0.062 inches. In the case of the surrounding sleeve (e.g., a thin-walled silicone tube) the wall thickness may be between about 0.008 and about 0.125 inches.
• The embodiments described herein may used for a variety of tasks such as, but not limited to, metering, pumping in product mixing or packaging, and controlling flow in laboratory environments.
• While the various embodiments of the present invention have been herein described, it is understood that various modifications can be made without departing from the scope of the invention.

Claims (13)

1. A syringe, comprising:

(a) an elastic sleeve defining a fluid chamber; and

(b) a plunger positioned within said elastic sleeve, wherein the outer diameter of said plunger is greater than the inner diameter of said elastic sleeve such that said plunger elastically deforms said sleeve during use.

2. The syringe ofclaim 1, wherein said elastic sleeve comprises at least one semi-rigid sleeve member positioned within at least one elastomeric sleeve member such that, upon deformation of said elastic sleeve, said at least one elastomeric sleeve member will provide a restoring force against the semi-rigid sleeve member such that said at least one semi-rigid sleeve member will be returned to its original size and shape

3. The syringe ofclaim 1, wherein said elastic sleeve comprising a syringe sleeve and a surrounding sleeve, wherein said fluid chamber is defined by the interior of said syringe sleeve and said syringe sleeve is positioned within the interior of said surrounding sleeve.

4. The syringe ofclaim 3, wherein said surrounding sleeve comprises an elastomeric sleeve which provides a compressive force against the outer surface of said syringe sleeve upon deformation of said sleeve during use.

5. The syringe ofclaim 4, wherein said syringe sleeve comprises a semi-rigid thermoplastic material.

6. The syringe ofclaim 5, wherein said syringe sleeve comprises a fluoroplastic chosen from the groups consisting of: PTFE, PFA and FEP.

7. The syringe ofclaim 4, wherein said surrounding sleeve comprises silicone.

8. The syringe ofclaim 1, further comprising a housing which encloses said elastic sleeve.

9. The syringe ofclaim 8, wherein said housing comprises a first end cap located at the proximal end of said syringe sleeve, a second end cap positioned at the distal end of said syringe sleeve, and at least one sidewall extending between said end caps.

10. The syringe ofclaim 9, further comprising a rod which extends distally away from away from said plunger, and further wherein said first end cap has an opening through which said rod extends, and further wherein said second end cap has at least one fluid passageway in fluid communication with said fluid chamber.

11. The syringe ofclaim 9, wherein said at least one sidewall comprises a tube secured to said first and second end caps such that an annular space is provided between said tube and said elastic sleeve.

12. The syringe ofclaim 11, wherein the proximal end of said second end cap includes a chamber and further comprising an insert member configured for insertion into said chamber of said second end cap, and further wherein the distal end of said elastic sleeve is secured within said chamber between the wall of said chamber and said insert member.

13. A syringe pump system, comprising:

(a) an elastic sleeve defining a fluid chamber;

(b) a plunger positioned within said elastic sleeve, wherein the outer diameter of said plunger is greater than the inner diameter of said elastic sleeve such that said plunger elastically deforms said sleeve during use;

(c) an intake conduit having a first check valve associated therewith and in fluid communication with said fluid chamber; and

(d) an output conduit having a second check valve associated therewith and in fluid communication with said fluid chamber;

wherein a fluid may be drawn into the syringe pump through said intake conduit and said first check valve, and thereafter expelled from said syringe pump through said output conduit and said second check valve upon reciprocation of said plunger.

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