Retractable syringe with improved delivery efficiency and locking system

Abstract

A plunger, a needle assembly and a retractable syringe comprising same are provided. The plunger comprises a plunger member and a plunger outer having a lock spring that prevents or impedes movement of the plunger member after needle retraction. The plunger further comprises another locking member for engaging the barrel to prevent or impede further movement of the plunger outer after delivery of fluid contents. The plunger member has a plunger seal which engages a retractable needle of the needle assembly for retraction. The retractable needle comprises a cannula and needle body with a plurality of fluid channels that co-operate with a fluid conduit of the plunger seal to efficiently direct fluid to the cannula. A needle retainer comprises a plurality of barbed arms releasably coupled to the needle body, whereby an ejector with tabs facilitates release of the retractable needle from the needle retainer to allow compressed spring-driven retraction.

Claims

1. A method of making a retractable syringe comprising: inserting a needle retainer into a barrel of the retractable syringe, the needle retainer comprising a plurality of centering bosses that facilitate self-centering of the needle retainer in the barrel; and adhering the needle retainer to the barrel by providing a flow of adhesive through guide channels of the needle retainer, the needle retainer comprising a circumferential groove, which together with said guide channels creates zones that facilitate or guide the flow of glue or adhesive for adhering the needle retainer to the barrel.

2. The method of claim 1, wherein the centering bosses allow contact between the needle retainer and the barrel at a plurality of separate points.

3. The method of claim 2, wherein any tolerance variation between the barrel and the needle retainer are absorbed by the crushing of at least one of the centering bosses when inserting the needle retainer into the barrel.

4. The method of claim 1, further comprising mounting a retractable needle so that the retractable needle is releasably engaged by the needle retainer.

5. The method of claim 4, wherein the needle retainer comprises a plurality of barbed arms that releasably engage said retractable needle.

6. The method of claim 4, wherein mounting the retractable needle includes inserting the retractable needle into a central aperture of the needle retainer.

7. The method of claim 4 further comprising at least partly filling the barrel with fluid contents.

8. The method of claim 7, further comprising inserting a plunger seal into the barrel.

9. The method of claim 8, further comprising coupling a plunger to the plunger seal.

10. The method of claim 7, further comprising adhering a collar comprising one or more releasing members to the barrel prior to at least partly filling the barrel with fluid contents.

11. The method of claim 1, wherein the needle retainer further comprises a rim at least partially defining the zones that facilitate or guide the flow of glue or adhesive.

12. The method of claim 1, wherein the flow of adhesive through the guide channels of the needle retainer is introduced from a needle end of the barrel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Non-limiting embodiments of the invention are described herein with reference to the following drawings wherein:

(2) FIG. 1 is a sectional view of an embodiment of a retractable syringe;

(3) FIG. 2 is a sectional view of an embodiment of a plunger;

(4) FIG. 3 is a sectional view of an embodiment of a plunger immediately before the end of injection of fluid contents of a syringe;

(5) FIG. 4 is a sectional view and a bottom view of an embodiment of a plunger seal;

(6) FIG. 5 is a sectional view of an embodiment of a needle assembly;

(7) FIG. 6 is a perspective view of an embodiment of a retractable needle;

(8) FIG. 7 is a perspective view of an embodiment of an ejector;

(9) FIG. 8 is a perspective view of an embodiment of a retainer;

(10) FIG. 9 is a sectional view of an embodiment of a needle assembly immediately before retraction of a retractable needle;

(11) FIG. 10 is a sectional view of an embodiment of a plunger immediately before retraction;

(12) FIG. 11 is a sectional view of an embodiment of a syringe during retraction of a plunger and retractable needle engaged therewith; and

(13) FIG. 12 is a sectional view of a lock formed between a barrel collar and a plunger outer after plunger retraction.

DETAILED DESCRIPTION

(14) Referring to FIG. 1, an embodiment of retractable syringe 100 comprises barrel 110 having plunger end 114 and needle end 115. Barrel 110 is preferably formed of glass. At plunger end 114 is located collar 113 having a releasing member in the form of release ring 130. Collar 113 may be mounted, glued, fitted or integrally formed with barrel 110. In embodiments where barrel 110 is formed of glass, suitably collar 113 is glued or otherwise adhered to barrel 110. In embodiments where barrel 110 is formed of plastic, collar 113 is preferably formed integrally with barrel 110 (e.g by moulding). Release ring 130 may be mounted, adhered or otherwise fitted to barrel 110, or may be co-moulded with collar 113 and barrel 110.

(15) At needle end 115 of barrel 110 is mounted needle assembly 900 comprising retractable needle 400 that comprises cannula 410 and needle body 420, needle seal 430, ejector 600 and retainer 300. Typically, syringe 100 is supplied with removable protective cover 121 over cannula 410.

(16) Syringe 100 further comprises plunger 200 comprising plunger seal 800 mounted thereto. Barrel 110 further comprises inside wall 118 which, together with needle seal 430 and plunger seal 800 define fluid space 120 inside barrel 110. In a preferred embodiment, fluid space 120 is prefilled with fluid contents to be delivered by retractable syringe 100.

(17) Typically, barrel 110 is formed of glass. Preferably, retainer 300 is glued or otherwise adhered to inside wall 118 of barrel 110. In use, plunger 200 is movable axially into fluid space 120 to facilitate delivery of fluid contents of retractable syringe 100.

(18) Referring particularly to FIG. 2, FIG. 3 and FIG. 4, plunger 200 comprises plunger member 210 comprising shaft 211, annular ledge 212 and seal-engaging member 216, which in this embodiment is screw threaded projection 217, which engages complementary, screw-threaded recess 820 of plunger seal 800 (see FIG. 4). In an alternative embodiment, seal engaging member 216 may be in the form of a snap lock projection that engages a complementary recess in plunger seal 800. In either case, the male-female connection between plunger member 210 and plunger seal 800 may readily be reversed so that the plunger member 210 has the female member and the plunger seal 800 has the male member.

(19) Plunger member 210 further comprises locking groove 219, the function of which will be described in more detail hereinafter.

(20) Plunger 200 further comprises plunger outer 220 having elongate body 221 with base 225 and head 222 in which is fitted cap 223. A first locking member comprises lock spring 224 mounted through slot 226 extending through head 222 and cap 223 to thereby assist assembly of plunger 200. Typically, lock spring 224 is an R-shape clip of stainless steel construction. Lock spring 224 and locking groove 219 co-operate to lock plunger member 210 and plunger outer 220 together at the end of retraction, as will be described in more detail hereinafter with reference to FIG. 12. Lock spring 224 preferably provides up to 100 Newton lockout resistance, which is a level of resistance desirable for syringe 100.

(21) Elongate body 221 further comprises a second locking member comprising locking finger 227 which has abutment 228. Engagement between locking finger 227 and release ring 130 of collar 113 will also be described in more detail hereinafter with reference to FIG. 12.

(22) Releasably, frangibly connected with plunger member 210 is control rod 230 comprising button 231, arm 232 and shaft 233. Plunger 200 further comprises compressed spring 270 which is mounted between plunger member 210 and plunger outer 220, held in an initially compressed state between annular ledge 212 of plunger member 210 and base 225 of plunger outer 220. Button 231 may have a textured surface to improve feel and grip for a user.

(23) As best shown in FIG. 3, control rod 230 is releasably coupled to plunger member 210 by way of shaft 233 which is releasably connected to plunger member 210 by frangible junction 234. Control rod 230 also releasably engages plunger outer 220 to thereby retain spring 270 in an initially compressed state held between annular ledge 212 of plunger member 210 and base 225 of plunger outer 220. Initially, ledge 235 of arm 232 abuts rim 229 of head 222 of plunger outer 220 to thereby retain control rod 230 and prevent axial movement of control rod 230 relative to plunger outer 220. However, arm 232 of control rod 230 is resiliently flexible and movable in the direction of the solid arrow shown in FIG. 3, which will allow disengagement of control rod 230 from plunger outer 220 to facilitate decompression of spring 270, as will be described in detail hereinafter.

(24) Referring particularly to FIG. 4, plunger seal 800 is of unitary construction and comprises seal body 840 and sealing ribs 850A, 850B, 850C that effect a fluid-tight seal between plunger 200 and inside wall 118 of barrel 110. Recess 820 of plunger seal 800 engages complementary seal-engaging member 216 of plunger member 210 (see FIG. 9). In this embodiment, recess 820 comprises a female screw thread 821 that engages male screw threaded projection 217 of plunger member. Plunger seal 800 further comprises needle engaging member in the form of recessed seat 810 that can receive segment 425 of retractable needle body 420. Plunger seal 800 also comprises recess 860 that receives fluid end 412 of cannula 410 towards the end of plunger 200 depression, prior to retraction of retractable needle 400, as will be described hereinafter. In addition, recess 860 of plunger seal 800 comprises fluid conduit 826.

(25) Needle assembly 900 is shown in more detail in FIG. 5, which comprises retractable needle 400, retainer 300, needle seal 430 and ejector 600. These components are individually described with reference to FIGS. 6, 7 and 8 respectively. Referring to FIG. 6, retractable needle 400 comprises cannula 410 having delivery end 411 and fluid end 412. Retractable needle 400 further comprises needle body 420 which comprises respective body segments 421, 422, 423, 424 and 425. Body segment 425 comprises fluid channels 426A, 426B. Needle body segment 424 comprises shoulder 427 and needle body segment 422 comprises shoulder 428. In FIG. 7, ejector 600 comprises ejector ring 610, bore 605 and respective base segments 620A, B, C separated by slots 621A, B, C. Base segments 620A, B, C respectively comprise tabs 622A, B, C which as shown in FIG. 5, engage shoulder 427 of body segment 424 of needle body 420.

(26) Referring to FIG. 8, retainer 300 comprises body 310 comprising circumferential groove 311, centering bosses 312, central aperture 313, rim 314 and guide channels 315, and further comprises arms 320A, 320B, respectively comprising hook-ends 321A, 321B. Circumferential groove 311 and guide channels 315 create zones which facilitate or guide the flow of glue or adhesive for adhering retainer 300 to inside wall 118 of barrel 110. Centering bosses 312 have been included to overcome the potential problem of centering retainer 300 in barrel 110 by providing a self-centering mechanism that simplifies centering of these components in high speed assembly and gluing machines, as would typically be used for the assembly of syringe 100. Centering bosses 312 allow contact between retainer 300 and barrel 110 at four separate points, with components produced for all extremes of tolerance. The tolerance variations between barrel 110 and retainer 300 are absorbed by the crushing of centering bosses 312. In the absence of these structures, a gap would be required between these components to allow for assembly at all tolerance extremes, which would require automated assembly machines to have a system for centering the parts prior to gluing. Alternatively, centering would have to be performed by a mechanism external to, or otherwise separate from, the assembly machines. This would not be practical for high speed assembly.

(27) Referring again to FIG. 5, needle seal 430 comprises sealing base 431 which seals against inside wall 118 of barrel 110 to prevent inadvertent leakage of fluid contents, body 432 comprising internal bore 433 and ledge 434.

(28) The sequence of events whereby retractable needle 400 is disengaged from retainer 300 to facilitate retraction of retractable needle 400 is as follows.

(29) Typically, syringe 100 is provided prefilled with fluid contents for delivery. Therefore, plunger 200 is provided in an initial position ready for depression to deliver the fluid contents of the syringe 100. During delivery of fluid contents, plunger 200 moves axially through barrel 110 in the direction of the hatched arrow in FIG. 9. Plunger seal 800 bears against needle seal 430, which in turn bears against ejector 600 thereby pushing tabs 622A, B, C of ejector 600 out of engagement with needle body 420. In order to provide an acceptable or desired level of retraction activation force, tabs 622A, B, C allow for tuning of the force to disengage ejector 600 from needle body 420 by adjusting the height of the tabs 622 until the push force required on needle seal 430 to force ejector 600 out of engagement with shoulder 427 of needle body 420 is at a level that is acceptable for use of syringe 100. The design of tabs 622A, B, C provides for simple machining of the injection-moulding tool to provide the optimum engagement fit to provide acceptable disengagement.

(30) Ledge 434 of needle seal 430 now rests on shoulder 427 of needle body segment 424. This facilitates moving needle seal 430 back up barrel with the needle 400 on retraction (and serves as a stop for forward travel), Further to this, ejector ring 610 moves hook-ends 321A, B of arms 320A, B radially outwardly in the direction of the solid arrows in FIG. 9, thereby disengaging segment 422 of needle body 420 from retainer 300 to release retractable needle 400 for subsequent retraction. At this point, recessed seat 810 of plunger seal 800 has engaged segment 425 of retractable needle body 420 and recess 860 has received fluid end 412 of cannula 410. This effectively couples retractable needle 400 to plunger member 210. Although not visible in FIG. 9, fluid channels 426A, 426B in segment 425 and fluid conduit 826 in recessed seat 810 in plunger seal 800 assist in channeling residual fluid from within recessed seat 810 into fluid end 412 of cannula 410. This minimizes dead volume (i.e a volume of undeliverable, hence wasted, fluid contents) and reduces the possibility of a hydraulic lock, to thereby improve the efficiency with which fluid contents of syringe 100 are delivered.

(31) Referring to FIG. 10, plunger 200 moves axially in the direction of the hatched vertical arrow until the end of injection of fluid contents, at which time abutment 228 of locking finger 227 of plunger outer 220 engages underside 131 of release ring 130 to thereby prevent movement of plunger outer 220 out of barrel 110.

(32) In order for retractable needle 400 to retract at the end of delivery of fluid contents, compressed spring 270 must decompress, which is facilitated by plunger member 210 disengaging from plunger outer 220. Again referring to FIG. 10, arm 232 of control rod 230 bears against release ring 130 of collar 113 at plunger end 114 of barrel 110. Release ring 130 forces arm 232 to move radially inwardly n the direction of the horizontal solid arrow and out of engagement with rim 229 of cap member 223 of plunger outer 220 in FIG. 10. This disengagement allows compressed spring 270 to decompress and push against ledge 212 of plunger member 210 to thereby retract plunger member 210 with control rod 230 coupled thereto, as shown in FIG. 11. This disengagement may also be accompanied by an audible and/or tactile signal (e.g. a click) which indicates to the user that retraction will occur. Retractable needle 400 is coupled to plunger seal 800 and so refracts with plunger member 210 in the direction of the arrow in FIG. 11 inside barrel 110, thereby being completely enveloped by, and contained within, barrel 110. While retraction of needle 400 is automatically driven by decompression of spring 270, the rate of retraction can be controlled by a user relaxing pressure (such as by way of thumb pressure) against button 231 of control rod 230.

(33) Referring to FIG. 12, at the end of refraction of plunger member 210, further movement of plunger member 210 relative to plunger outer 220 and/or barrel 110 is prevented by lock spring 224 snap locking around locking groove 219 in plunger member 210. The locking of plunger member 210 at the end of retraction prevents inadvertent removal of plunger member 210 from plunger outer 220 and also prevents inadvertent depression of plunger member 210, both of which would expose needle end 411, and thereby expose the user to a potential needle stick injury.

(34) At the end of retraction of plunger member 210 and retractable needle 400, control rod 230 can be broken from plunger member 210 at frangible junction 234 and manually removed from retractable syringe 100 and discarded as clean waste so that there is little if any plunger 220 protruding externally from barrel 110 with which to attempt to force plunger 200 back into barrel 110 and attempt to re-engage the needle (not shown).

(35) In light of the foregoing it will be appreciated that the present invention provides a relatively simple, robust and inexpensive syringe that is automatically disabled with little or no assistance from the user to thereby prevent, or at least minimize the likelihood of, re-use of the syringe and/or needlestick injury by a used syringe.

(36) More particularly, dual locking systems are provided whereby the plunger outer is locked to the barrel and the plunger member is locked to the plunger outer to thereby prevent removal and/or further movement of the plunger. Another particular advantage is provided by the lock spring which can resist up to 100 Newtons force to prevent or impede further movement of the plunger member after retraction. By providing dual locking systems, inadvertent failure of one or the other locking systems, or overcoming one or the other locking systems through tampering by an illicit user, does not result in the complete failure of plunger lockout.

(37) It will also be appreciated that the fluid conduits in the retractable needle body and in the plunger seal provide more efficient delivery of fluid contents timed to occur just before retraction of the needle. In cases where the fluid contents are an expensive drug or other compound, on a mass produced scale this improved efficiency can result in considerable cost savings. Furthermore, the retractable syringe retainer provides a convenient self-centering system for mounting into the barrel which greatly assists high speed syringe assembly. The guide channels of the retainer also assist rapid, automated adhesion of the retainer in the barrel during syringe assembly.

(38) Another advantage is provided by the ejector tabs described herein that provide an acceptable or desired level of retraction activation force. Adjustment of tab height allows for tuning of the force to disengage the ejector from the retractable needle body, and hence the push force required to force the ejector out of engagement with the retractable needle body.

(39) Throughout the specification, the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. Various changes and modifications may be made to the embodiments described and illustrated without departing from the present invention.

(40) The disclosure of each patent and scientific document, computer program and algorithm referred to in this specification is incorporated by reference in its entirety.