WO2014072994A2

WO2014072994A2 - Folded plunger auto retractable syringe for single use

Info

Publication number: WO2014072994A2
Application number: PCT/IN2013/000656
Authority: WO
Inventors: Jai Hind RATHORE; Bharati RATHORE; Pratibha RATHORE; Neelam RATHORE; Bhuvan Chandra RATHORE
Original assignee: Rathore Jai Hind; Rathore Bharati; Rathore Pratibha; Rathore Neelam; Rathore Bhuvan Chandra
Priority date: 2012-11-08
Filing date: 2013-10-29
Publication date: 2014-05-15
Also published as: WO2014072994A3

Abstract

The present subject matter relates to an auto retractable safety syringe (100) for single use which includes a needle carrier assembly (108) and a folded plunger assembly (200) respectively for inserting in an outermost barrel (110). The folded plunger assembly (200) is provided with an inner plunger barrel (102), an outer plunger barrel (104) and a plunger plug (106). The inner plunger barrel (102) is provided with at least one oppositely positioned circumferential C-groove (122) on outer surface at its proximal end P, a pair of oppositely positioned finger locks (118 and 120) on either end to get engaged with an outer plunger barrel (104), and a piston seal holder (114) structured at the proximal end P for holding a piston seal (116). The outer plunger barrel (104) includes at least one pair of oppositely positioned finger locks (156 and 158) on both ends and a second piston seal holder (124) at proximal end P for holding another piston seal (126). The folded plunger assembly is also provided with the plunger plug (106) which is designed with at least one uniform circumferential groove (136) wherein the plunger plug (106) is centrally designed with a longitudinally furrowed knob (140) at its proximal end P. The present subject matter also discusses about the needle carrier assembly (108) for housing in the outermost barrel (110) in which the needle carrier assembly (108) includes a seat and internal locking arrangement (148) provided in a central axial passage opening designed in a cavity (146) at the distal end D to snap lock the furrowed knob (140) present in the plunger plug (106), a needle (152) provided with a needle cover (154) at the proximal end P of the needle carrier assembly (108), and the elastic O-rings (132) to support and hold the needle carrier assembly 108 inside the outermost barrel (110), and to dislodge the assembly on completion of injection. The present invention further explains that the outermost barrel (110) designed to receive the folded plunger assembly (200) alter getting in the needle carrier assembly (108), wherein the outermost barrel (110) is provided with a finger rest (128), a uniform obtuse-angled L-shaped inner circumferential conical groove (130) and a conical jacket opening (134) at the proximal end of the outermost barrel (110).

Description

FOLDED PLUNGER AUTO-RETRACTABLE SYRINGE FOR SINGLE USE

TECHNICAL FIELD

The present invention relates to a safety syringe having an auto retractable needle for use in the medical or dental profession or in personal drug administration so that the physicians, surgeons or other needle operators may be protected from the needle-stick injury during its use. The invention, in particular, relates to an assembly of the safety syringe which is simple and easy in handling, in which the hypodermic needle retracts itself automatically by virtue of self generated vacuum and encapsulate within the barrel as soon as the last drop is injected in the body of patient. The syringe thereafter becomes finally locked to become non-reusable. The handling of syringe docs not require any special training to the operators. It is simple in manufacture.

BACKGROUND

Generally, syringes arc simple axial piston pumps with a plunger that fits tightly in a cylindrical barrel. The plunger can be pulled and pushed along inside the barrel, thereby creating a pressure gradient. Additionally, many syringes carry a sharp and penetrating hollow needle that is intended to puncture the skin, mucous membrane and internal organs of humans or animals for injection or removal of fluids, aerosols, or particulate suspensions.

Recently, there has been noticed growing evidences of needle-stick injuries for, not restricted to medical professionals, children playing in park, a street walkers and the like. Anyone affected by needle-stick injuries may be infected with serious blood born diseases. Further the danger of these injuries may escalate to possible inlections from HIV and hepatitis B, even to those medical practitioners who work with these used needles in their normal course of business.

There have been a number of proposals aimed at reducing these needle-stick injuries. Such proposals also include auto-retractable syringes. A num ber of patents and products have also been introduced in the markets relating to various auto-retractable syringes. In the retractable syringes, when the injection has been administered, the piston is pushed away from the leading end of the barrel by a spring or a similar biasing means and the needle tip is accordingly retracted into the barrel. However these syringes often suffer from the disadvantages i.e. splash occurs back when the needle is caused to be retracted, which makes the injection process complicated and brings inconvenience for doctors and nurses. Conventionally, to activate the auto-retraction, the plunger of the syringe needs a hard push beyond the normal pressure. Therefore, if the needle of the syringe is drawn from the patient before the auto retraction is activated then it matters little how violent the initial kick-back is. On the other hand, if the auto retraction of the needle in the syringe is activated whilst the needle is in the body of the patient, either accidentally or deliberately, it may be quite uncomfortable or cause undesirable damage to the tissues in which the needle is inserted. There is another kind of syringe in which the needle is retracted into the barrel under the action of spring after injection. However, in such kind of retractable syringes, the needle is retracted too fast which may result in bursting out of blood under the body pressure from the punctured hole on the body, which further brings secondary cross infection. The conventional syringes also lack in full-proof locking arrangement as well as effective retraction mechanism to prevent and restrict further use of syringes once used.

Thus, there is a urgent need for auto retractable single use syringes which may overcome the above mentioned drawbacks and shortcomings to provide a safe, reliable and user friendly auto retractable syringes that can protect against accidental injuries loo.

SUMMARY

An object of the present subject matter is to provide a folded pl unger auto retractable syringe for single use.

Another object of the present subject matter is to provide a folded plunger auto retractable syringe with a folded plunger assembly.

Another object of the present subject matter is to provide a folded plunger assembly that includes an inner plunger barrel, an outer plunger barrel and a plunger plug.

Another object of the present subject matter is to provide a folded plunger assembly that includes an outer-most barrel to hold the folded plunger barrel.

Another object of the present subject matter is to provide a auto retractable syringe with a plunger plug to be inserted in an outermost barrel.

Another object of the present subject matter is to provide the plunger plug with a longitudinally furrowed knob. Another object of the present subject matter is to provide a needle carrier to hold' the needle.

Another object of the present subject matter is to provide an O-ring to support the needle carrier and to dislodge the needle carrier to actuate the retraction mechanism.

Another object of the present subject matter is to provide the plunger plug with a longitudinally furrowed knob.

Another object of the present subject matter is to create a vacuum when the plunger is pulled within the barrel.

Another ob ject of the present subject matter is to uncover the needle of the syringe during the time of injecting or retracting the fluid.

Another object of the present subject matter is to lock the plunger barrel inside the outermost barrel after usage.

Another object of the present subject matter is to provide the inner plunger barrel with a pair of oppositely positioned finger locks on either end to get engaged with the outer plunger barrel.

Another object of the present subject matter is to provide the inner plunger barrel with a piston seal holder structured at the proximal end for holding a piston seal.

Accordingly, the subject matter described herein generally relates to a safety syringe having an auto retractable needle for use in medical or denial profession or in personal drug administration so that the physicians, surgeons or other needle operators may be protected from needle-stick injuries after its use. Therefore, the invention, in particular, relates to an assembly of the safety syringe which facilitates simple operation and easy handling, in which the hypodermic needle retracts itsel f automatical ly by virtue of self generated vacuum and encapsulates within the barrel as soon as the last drop is injected in the body of patient. The syringe thereafter becomes automatically locked to become non-reusable. The handling of syringe does not require any special training to the operators. It is also simple in manufacture. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

Fig. 1 (a) illustrates a line diagram of an inner plunger barrel of a folded plunger auto- retractable syringe.

Fig. 1(b) illustrates a line diagram of an outer plunger barrel of a folded plunger auto- retractable syringe. .

Fig. 1 (c) illustrates a line diagram of a plunger plug of a folded, plunger auto-retractable syringe.

Fig. 2 illustrates a line diagram pf a folded plunger assembly of a folded plunger auto- retractable syringe.

Fig. 3(a) illustrates a line diagram of needle carrier of a folded plunger auto-retractable syringe. . .

Fig. 3(b) illustrates a line diagram of an outermost barrel of a folded plunger auto- retractable syringe, ^'\ ,

Fig. 3(c) illustrates a line diagram of a needle carrier assembly housing in the outermost barrel of a folded plunger auto-retractable syringe. ,

· , Fig. 4 illustrates a line diagram of an assembly for a complete folded plunger auto 'retractable syringe.

Fig. 5 illustrates inner parallel grooves (x and y) provided at the distal end of the outermost barrel of a folded plunger auto-retractable syringe.

Fig. 6 illustrates a complete assembly of a folded plunger auto-retractable syringe.

Fig. 7 illustrates a united assembly of the two plunger barrels in a folded plunger auto- retractable syringe. Fig. 8 illustrates the push of the plunger within the barrel in a folded plunger auto- retractable syringe.

Fig. 9 illustrates the pull of the plunger within the barrel in a folded plunger auto- retractable syringe.

Fig. 10 illustrates retraction and encapsulation of needle assembly inside the outermost barrel and a complete lock of a plunger barrel in folded plunger auto-retractable syringe.

DETAILED DESCRIPTION

The embodiments of the present subject matter are described in detail with reference to the accompanying drawings. However, the present subject matter is not limited to these embodiments which are only provided to explain more clearly the present subject matter to the person ordinarily skilled in Hie art of the present disclosure, hi the accompanying drawings, like reference numerals are used to indicate like components.

The invention is explained with respect to a safety syringe incorporating an auto retractable needle assembly therein. Generally, the safety syringe includes a syringe bane! and a plunger slidably located therein. The plunger is designed with a proximal and a distal end with piston means associated therewith at its proximal end so as to be sealingly slidable within the barrel.

The safety syringe 100, according to a preferred embodiment of the present subject matter, is structurally constructed with an inner plunger barrel 102, an outer plunger barrel 104, a plunger plug 106, a needle carrier 108 and an outermost barrel 110. The inner plunger barrel 102, as shown in FIG. 1 (a), is a uniformly elongated hollow cylindrical tubular body provided with a thumb rest 112 at its distal end 1) and a piston seal holder 114 at the proximal end for holding a piston seal 116, in an embodiment of the present subject matter. The inner plunger barrel 102 is designed with at least one oppositely positioned, outwardly protruded pair of finger locks (118, 1.20), opening and directing outwardly towards distal 1) as well as proximal V ends respectively, The finger locks (1 18 and 120) are designed and shaped by cutting the wall of plunger barrel 102. The inner plunger barrel 102 is also provided with two uniform circumferential oppositely face to face positioned conical C-grooves 122 on outer surface at proximal end. The outer plunger barrel 104, as shown in FIG. 1 (b), is a uniformly elongated hollow cylindrical tubular body provided with a second piston seal holder 124 at proximal end for holding another piston seal 126. The outer plunger barrel 104 is designed with the provision of at least one oppositely positioned pair of finger locks (156 and 158) opening and directing towards the either end of the outer plunger barrel 104.

In the embodiment of present subject matter the tooth T-l of finger lock 156 is directed to distal end and is protruded inwardly in normal slate. The proximal surface of tooth T-l is designed perpendicular to the inner surface of barrel 104, whereas the distal surface is obliquely inclined to the proximal end. finally constituting an oblique notch. The tooth T~l of finger lock 156 is almost double in thickness in comparison to the walls of the outer plunger barrel.

In another embodiment of present subject matter, the finger lock 158 is directing to the proximal end and protruded outwardly in normal state. It is provided with tooth T-2 and T-3. The half of the proximal portion of the outwardly protruded tooth T-2 is obliquely inclined to the distal end, whereas the distal portion of tooth T-2 is perpendicular to the outer surface of barrel 104, finally constituting an outwardly protruded oblique notch. The proximal as well as distal surfaces of tooth T-3 are parallel to each other as well as perpendicular to the outer surface of barrel 104. The thickness of tooth T-3 of finger lock 158 is also almost double in comparison to the walls of the outer plunger barrel.

In normal state the tooth T-2 protrudes in outward direction whereas the tooth T-3 remains in the level of inner surface of barrel 104, The teeth T-2 and T-3 are designed and shaped by cutting the walls and surfaces of the barrel 104. Tooth T-2 is shaped and designed in such a manner that it may conveniently seat inside the inner circumferential conical groove 144 of the outer-most barrel 110, in order to snap lock the barrel 104 with the outermost barrel 110. The tooth T-3 is also designed and shaped in such a manner, so that it may conveniently seal within the circumferential groove 136 of the plunger plug 106 when the tooth T-2 is pressed inwardly,

FI G. 3(b) shows the outermost barrel 110 which is a uniformly elongated hollow cylindrical tubular body, provided with a finger rest 128, a uniform obtuse-angled L-shaped inner circumferential conical groove 130 and two oppositely positioned parallel inner grooves (x and y), opening at the distal end of barrel 110 in an embodiment of the present subject matter. The conical groove 130 is inclined obliquely to the proximal end of the barrel 110 to facilitate sliding of an elastic O-ring 132 and snap-lock the plunger assembly inside the outermost barrel 110 after the finger Jock 118 becomes in normal state with the completion of the injection. The outermost barrel 1 10 also includes a conical jacket 134 opening outside at proximal end, in an embodiment of the present subject matter.

In an embodiment of the present subject matter, the outer diameter of the outer plunger barrel 104 is uniformly equal to the inner diameter of the outermost barrel 110 and uniformly equal to the outer diameter of distal portion D of the inner plunger barrel 102. Further, the inner diameter of outer plunger barrel 104 is uniformly equal to the outer diameter of remaining proximal portion V of inner plunger barrel 102. In another embodiment of the present subject matter, the outer diameter of the distal portion of the inner plunger barrel 102 is uniformly equal to the outer diameter of the outer plunger 104 and further equal to the inner diameter of the outermost barrel 1.10. Here, the outer diameter of remaining proximal portion of inner plunger 102 is uniformly equal to the inner diameter of the outer plunger barrel 104.

FIG. 1(c) illustrates the plunger plug 106 in which the outer diameter ivS equal to the inner diameter of outer plunger barrel 104 of the folded plunger assembly, in an embodiment of the present subject matter. The plunger plug 106 is provided with a thickness 138 having uniform circumferential groove 136. The plunger plug 106 is centrally designed with a longitudinally furrowed knob 140 at its proximal end. The furrowed knob 140 is positioned parallel to the outermost barrel 1 10. The furrowed knob 140 is advantageously provided with a lock element 142 at proximal end. The distal portion of this plunger plug 1.06 is inserted in the outer plunger barrel 104 through its proximal end, positioning the circumferential groove 136 of plunger plug 106 in alignment of inwardly protruded tooth (T-3) of linger lock 158 as shown in FIG. 1 (b).

The safety syringe 100 also includes a conical needle carrier assembly 108, as shown in FIG. 3(a), provided with a longitudinal axial passage at its centre which is parallel to (he plunger barrel 104, in an embodiment of the present subject matter. The axial passage widens at distal end to constitute a cavity 146, which provides a seat and internal locking arrangement 148 to capture the knob 140 provided in the plunger plug 106, as explained earlier with reterence to FIG, 1(c). The inner diameter of cavity 146 is equal to the outer diameter of the knob 140. The proximal end of the axial passage opens in a straight hollow hypodermic needle 152, The distal portion of needle carrier 108 is designed parallel to the inner surface of the outermost barrel 1 10. The conical needle carrier 144 is designed with a col lar 150 at proximal end of its outer surface. Further, this conical proximal end extends in a removable hollow straight needle 152 attachable at proximal end, in an embodiment of the present subject matter. The hollow needle 152 is advantageously encapsulated in a removable needle cover 154. The conical needle carrier 144 is also structured with an elastic O-ring 132 having inner diameter and thickness equal to the outer diameter and thickness of distal portion of conical needle carrier 144. The outer diameter of O- ring 132 is equal to the slightly enlarged inner proximal diameter of the outer barrel 1 10 in which the outer proximal circumferential edge of O-ring 132 is round in shape.

While assembling the syringe 100 in a preferred embodiment of the present subject matter, the proximal end of inner plunger barrel 102 is inserted in the outer plunger barrel 104 through its distal end in such a way that the inwardly protruded tooth (T-l) of finger lock 156 becomes in alignment of the flat portion provided between two oppositely positioned face to face circumferential conical C-grooves 122 at the outer surface of inner plunger barrel 102, so that the tooth (T-l) of finger lock 156 may conveniently slide over the flat portion available between the two C-grooves 122. After slight insertion of inner plunger barrel 102 into the outer plunger barrel 104, the lock 120 is slightly pressed inwardly to facilitate the complete insertion of rest of the inner plunger barrel 1 02 into the outer plunger barrel 1.04. With the slide of the inner plunger barrel 102 inside the outer plunger barrel 104, the normal position of inwardly protruded finger lock 152 is changed to become strained and the tooth (T-l) protrudes in outward direction. At this stage, the distal portion of plunger plug 106 is inserted in the outer plunger barrel 104 through its proximal end, positioning the circumferential groove 136 of plunger plug 106 in alignment of inwardly protruded tooth (T-3) of finger lock 158 as shown in FIG. 1 (b). lii this way, the inner plunger barrel 102 is inserted in the outer plunger barrel 104 at its full length to constitute a folded plunger assembly 200 along with plunger plug 106, as shown in FI G. 2.

Now, the plunger assembly 200 is ready to be inserted in the outer-most barrel 110, but the conical needle carrier 108 is first inserted in the outermost barrel befoi'e the insertion of folded plunger assembly 200 along with plunger plug as shown in FIG. 4. The proximal end of needle carrier 108 is first inserted in the outermost barrel 1 10 along with O-ring 132 through its distal end, keeping the needle 152 directing to proximal end of the barrel 110. The needle assembly easily slides inside the outermost barrel .110. After inserting the needle carrier assembly 108 in outer-most barrel 110, the proximal end of the plunger assembly 200 is inserted into the outermost barrel 1 10 with the help of thumb rest 112 and the finger rest 128 in such a way that the outwardly protruded tooth (T-l) of finger lock 156 becomes in alignment of the groove (x and y) provided at the distal end of outermost barrel 1 10, as shown in FIG. 5. which finally slides into the inner circumferential conical groove 130 provided at the inner surface at the distal end of outermost barrel 110.

The tooth (T-2) has been designed to slide into the outermost barrel 1 10 easily and conveniently through the parallel grooves (x and y). On further pressing the plunger assembly, 200 the tooth T-2 of the finger lock 158 is automatically pressed inwardly and seats conveniently inside the circumferential groove 136 of the plunger plug 106, holding the plug firmly. This makes the plunger plug 106 to get firmly held inside the outer plunger barrel 104 at its proximal end. In an embodiment of the present subject matter, a further push of the plunger barrel assembly inside the outermost barrel 110 traps the air between the plunger assembly 200 and the needle assembly which prevents the danger of insertion of knob 140 into the opening cavity 146 of the conical needle carrier 144.

When the tooth (T-l ) of finger lock 156 , strained in outward direction occupies the seat in the inner circumferential groove 130, the plunger assembly 200 is rotated in either direction (clockwise or anticlockwise) by approximately 60-90° angle so that the plunger assembly 200 becomes fixed at this position due to the misalignment of outwardly protruded lock 156 occupying seat in groove 130 from the parallel grooves x and y. Now, this plunger assembly 200 may neither be pushed further inside the outermost barrel 110, nor it may be pulled out of the barrel 1 10 as evident from FIG. 6.

FIG. 6 illustrates the complete assembly of the safety syringe 100 according to the present subject matter. While working with folded plunger auto-retractable syringe, the user has only option to pull out the inner pl unger barrel 102 by holding the safety syringe 100 with the help of the thumb rest J 12 and the finger rest 128. When the inner plunger barrel 102 is pulled out at its full length, a vacuum V is created between the plunger plug 106 and the piston seal 116 of the inner plunger barrel 102.

On pulling the inner plunger barrel 102 out of the syringe, the outwardly strained finger lock 156 already occupying the circumferential groove 130 of the outer-most plunger barrel 1 10, as soon as comes in alignment Of C-groove 122 provided on the surface of inner plunger barrel 102 at proximal end, the outwardly strained finger lock 156 becomes in normal state and snap locks C-groove 122. Simultaneously, the finger lock 120 opens in outward direction and snap holds the walls of inner and outer plunger barrel (102 and 104) firmly. The two plunger barrels (102 and 104), thus unite together and catch hold each other firmly to behave like a single plunger barrel as shown in FIG. 7.

In case, the united plunger barrel is attempted to be pulled out completely from the outer most barrel 110, the tooth T-2 of finger lock 1 58, when comes in alignment with the conical circumferential groove 130 of the outer most barrel, restores its normal state and expands in outward direction to seat inside the conical groove 130 conveniently, due to the space provided by the groove 130, which ultimately prevents further retraction of united plunger barrel in backward direction. Thus, the united plunger barrel may not be removed from the outer plunger barrel 110. On the other hand, on pressing the united plunger barrel in forward direction, the L- shaped obtuse-angled conical design of the inner circumferential groove 1 30, being inclined to proximal end, facilitates the tooth T-2 to slide the united plunger barrel easily in forward direction. In this way, the united plunger barrel may, however, be moved in back and forth direction within the outermost plunger barrel, but cannot be removed out from the outer plunger barrel.

The united plunger barrel is now pushed into the outermost barrel 110 which results sliding of needle assembly 108 in forward direction. The needle assembly finally seals inside the conical jacket 134 at the proximal end of the outermost barrel 110. The elastic O-ring 132, associated with the conical needle assembly, occupies its seat inside the proximal portion of the barrel 1 10 having slightly enlarged diameter, after crossing over the collar formed within the proximal portion of outer most barrel 1 10 due to slightly enlarged diameter of axial passage. This makes^' the needle 152 to come out of the opening provided at the proximal end of outermost barrel 1 10 along with protecting cover 154 as il lustrated in FIG. 8.

FIG. 9 shows how the needle cover 154 is removed to uncover the needle 152. The needle may also be replaced as per the requirement with the help of inner lock provided therein. The medicinal dosage may be sucked inside the outermost barrel 110 by pulling the plunger assembly 200. The medicinal dose may also be injected into the body of the patients as shown in another embodiment of FIG. 8. While injecting the dose with the safety syringe 100, according to the present subject matter, the proximal end of outer barrel 124 pushes the O-ring 132 in forward direction to dislodge the needle carrier 108, when injection is likely to complete. The forward movement of plunger assembly 200 makes the furrowed knob 140 of the plunger plug 106 to insert into the cavity 146 of the needle carrier 108, which gets snap-locked therein the cavity 146 as soon as the last drop of medicine is injected in body of patient. In the same embodiment of the present subject matter, the tooth (T-2) of finger lock 158, provided at the proximal end of outer plunger barrel 104 becomes in unstrained (normal) slate as soon as it becomes in alignment of conical circumferential groove 144 provided at the inner surface of outermost barrel 110. The - inner tooth (T-3) simultaneously leaves the plunger plug free which moves in backward direction (to the distal end of the plunger barrel) due to the vacuum V already existing inside the plunger barrel. Consequently, the plunger-plug attached with the needle-carrier 144 along with needle 152 smoothly and gently slides in backward direction to the distal end of plunger barrel, thus, retracting the needle 152, and finally encapsulating it inside the plunger-barrel. The finger lock 118 also simultaneously becomes in alignment with the conical circumferential groove 130 of the outermosl barrel and opens itself automatically to expand in outward direction to become in normal state, which ultimately snaps lock the inner circumferential groove 130, resulting in the complete lock of plunger barrel inside the outermost barrel 110 as shown in FIG. 10. This results in the locking of the plunger assembly 200 inside the syringe 100 along with retracted needle 152, which advantageously renders the syringe assembly completely useless for any further use.

The folded plunger auto-retractable syringe 100 according to present subject matter facilitates an automatic control on the movement of plunger inside the barrel, thus providing the apt pressure and method of injecting as well as retracting the fluid through the syringes. Further, the retractable syringes 100 as per the present subject matter may be disposed off safely in a container as there is no option to re-use such used syringe. In other words, the present invention facilitates the in-operation of the used syringe by virtue of the retention of collapsed needle encapsulated within the barrel. Hence, possible infections from HIV, hepatitis B, and the like may be reduced to a greatei- extent. Additionally, the safety syringe according to the present subject matter is low-cost, user-friendly and easy in manufacture that encourages its usage too. Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a l imiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to the person skilled in the art upon reference to the description of the invention. It is, therefore, contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined.

Claims

I We Claim:

1. An auto retractable safety syringe 100 for single use comprising:

a folded plunger assembly 200 for slidably inserting in an outermost barrel 1 10, the folded plunger assembly 200 comprising:

an inner plunger barrel 102 provided with at least one oppositely positioned circumferential C-groove 122 on outer surface at its proximal end P, a pair of oppositely positioned finger locks (118 and 120) on either end to get engaged with an outermost barrel 1 10 and the outer plunger barrel 104 respectively, a piston seal holder 3 14 structured at the proximal end P for holding a piston seal 116;

the outer plunger barrel 104 comprising a second piston seal holder 124 at proximal end P for holding another piston seal 126; wherein the outer plunger barrel 104 comprising at least one pair of oppositely positioned finger locks (156 and 158) on either ends wherein,

the finger lock (156 and 158), directing to the distal as well as proximal ends respectively, having thickness almost double to that of the walls of plunger barrel 104;

the finger lock 156 being protruded inwardly in normal state and having a conical tooth Τ-Ϊ , wherein, the proximal surface of tooth T-l is designed perpendicular to the inner surface of barrel 104, whereas the distal surface is obliquely inclined to the proximal end, finally constituting an oblique notch

the finger lock 158 protruded outwardly in normal state and having tooth (T-2 & T-3) at the outer and inner surfaces respectively, wherein

the half of the proximal portion of the outwardly protruded tooth T-2 is obliquely inclined to the distal end, whereas the distal portion of tooth T-2 is perpendicular to the outer surface of barrel 104, finally constituting an outwardly protruded oblique notch; the proximal as well as distal surfaces of tooth T-3 are parallel to each other as well as perpendicular to the outer surface of barrel 104.

a plunger plug 106 designed with atleast one uniform circumferential groove 136 wherein the plunger plug 106 is centrally designed with a longitudinally furrowed knob 140 at its proximal end P;

a needle carrier assembly 108 for housing in the outermost barrel 110, the needle carrier assembly 108 comprising:

a seat and internal locking arrangement 148 provided in a central axial passage opening designed in a cavity 1.46 at the distal end D to snap lock the furrowed knob 140 present in the plunger plug 106;

a needle 152 provided with a needle cover 154 at the proximal end P of the needle carrier assembly .108;

elastic O-rings 132 to support and hold the needle carrier assembly 108 inside the outermost barrel 110, and to dislodge the assembly on completion of injection; the outermost barrel 1.10 designed to receive the folded plunger assembly 200 after getting in the needle carrier assembly 108, wherein the outermost barrel 110 is provided with a finger rest 128, a uniform obtuse-angled L-shaped inner circumferential conical groove 130 and a conical jacket opening 134 at the proximal end of the outermost barrel 110.

2. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the inner diameter of the outermost barrel 110 is uniformly equal to the outer diameter of the outer plunger barrel 104.

3. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the inner plunger barrel 102 is designed with a thumb rest 112 at its distal end D.

4. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the finger lock 156 comprises teeth (Tl and T2) obliquely inclined to the distal end D of the outermost barrel 110.

5. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the finger lock 158 comprises teeth T-2 & T3 obliquely inclined to the proximal end P of the outermost barrel 110.

6. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the outer diameter of the outer plunger barrel 104 is uniformly equal to the inner diameter of the outermost barrel 1 10.

7. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the outer plunger barrel 104 comprises of a finger rest 128 at the distal end D.

8. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the outer diameter of the plunger plug 106 is equal to the inner diameter of the outer plunger barrel 1 10.

9. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the inner diameter and thickness of the elastic O-ring 132 is equal to the outer diameter and thickness of the distal portion of the needle carrier 154.

10. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the outermost barrel 110 is designed to receive the needle carrier 154 and the folded plunger assembly 200 respectively.

11. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein during insertion of the inner plunger barrel 102 in the outer plunger barrel 104, the tooth T-3 of the finger lock 158 becomes in alignment of a flat portion provided between two oppositely positioned face to face circumferential conical c-grooves 136 at the outer surface of the inner plunger barrel 102.

12. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the two inner circumferential conical grooves 122 includes a first conical groove designed at the inner surface of distal end D and a second conical groove designed at the inner surface of the proximal end P.

13. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein during insertion of the folded plunger assembly 200 in the outermost barrel 110, the tooth (T-l) of finger lock 156 is positioned in the inner parallel grooves (x and y) provided at the distal end D of the outermost barrel 110.

14. The auto retractable safety syringe 1 10 for single use as claimed in preceding claims, wherein the seating of tooth in the outer circumferential groove firmly held and control the movement of the plunger plug 106.

15. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein once the tooth T-l of finger lock 156 occupies the seat in the groove 130, the plunger assembly 200 is rotated in either direction by approximately 60 to 90 degrees to block the movement of the plunger assembly 200 inside the outermost barrel 110.

1.6. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein air is trapped between the plunger assembly 200 and the needle carrier assembly 108 on pushing the plunger barrel inside the outermost barrel 1 10 which prevents the knob 140 from damages.

17. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the finger lock opens and snaps hold the walls of the inner and outer plunger barrel 110 firmly to unite and catch hold each other as a united plunger barrel.

18. The auto retractable safety syringe 100 for single use as claimed in claim 1 8, wherein the needle 152 is also provided with a needle cover 154 which gets uncovered as the united plunger barrel is further pushed inside the outermost barrel 110.

19. The auto retractable safety syringe 100 for single use as claimed in preceding claims, wherein the finger lock opens and snap locks in the inner circumferential groove 130 provided at the distal end D of the outermost barrel 110 resulting in complete lock of the plunger barrel inside the outermost barrel 1 10.