A micro-dose injector with simultaneous needle tip retracting function

Abstract

The application discloses a micro-dose injection syringe with a needle tip capable of synchronous retraction, which comprises a syringe jacket, a core rod and a needle assembly, further comprises a connecting rod arranged in the syringe jacket and a double-layer gear rotatably arranged on the syringe jacket; the core rod is provided with a first rack part, the connecting rod is provided with a second rack part, the first rack part is engaged with one gear of the double-layer gear, and the second rack part is engaged with the other gear of the double-layer gear; the needle assembly comprises an outer needle and an inner needle slidably sleeved in the outer needle, the rear end of the inner needle is fixedly connected with an inner needle seat, the inner needle seat is fixedly connected with the front end of the connecting rod; a pressing block is fixedly arranged on the connecting rod, a guide groove extending in the axial direction is formed in the syringe jacket, the pressing block passes through the guide groove and extends out of the syringe jacket. The application realizes synchronous retraction of the needle tip during the injection process, and significantly improves the precision of micro-dose injection.

Description

Technical Field

[0001] This invention relates to the field of medical syringe technology, and in particular to a micro-drug delivery syringe in which the needle tip can retract synchronously during injection. Background Technology

[0002] See Figure 1 The figure shows a schematic diagram of a commonly used syringe structure in the prior art, which mainly includes an outer sleeve 10, a core 20, and a needle 30 fixedly disposed at the front end of the outer sleeve 10. During the injection operation, the needle 30 is always in the extended state and occupies the limited space inside the tissue, making it impossible to retract while injecting the drug, thus causing a series of clinical problems.

[0003] In ultra-micro-volume drug delivery procedures such as intravitreal injections and subretinal injections in ophthalmology, the clinical requirements for drug delivery precision and location accuracy are extremely high. Taking the treatment of age-related macular degeneration and diabetic retinopathy as examples, the single dose is typically only a few microliters, the target tissue thickness is less than 200 micrometers, and the margin for error is extremely small. Traditional syringes (such as...) Figure 1 (As shown in the diagram) Because the needle is fixed, the needle tip and body always occupy the internal space of the tissue after puncture, resulting in a reduction in the effective volume of the drug that can actually diffuse. During injection, the drug tends to diffuse and overflow along the puncture path and interstitial spaces, rather than concentrating on the target point. This phenomenon not only wastes the drug but also seriously affects the precise control of the dosage, thereby weakening the treatment effect and increasing the risk of ocular complications.

[0004] This contradiction also exists in scenarios requiring ultra-low volume targeted drug delivery, such as precise local drug delivery in dermatology, micro-injection in pediatrics, and small animal experiments. Traditional syringes lack the function of actively retracting the needle during injection, so the needle always occupies the tissue cavity. During drug delivery, the effective space within the cavity is insufficient, and the drug solution is forced to diffuse into low-pressure areas, which can never resolve the inherent conflict between "needle occupancy and targeted drug deposition".

[0005] Currently, some syringe designs have incorporated needle retraction mechanisms, but their technical focus is primarily on preventing needlestick injuries after injection, aiming to mitigate occupational exposure risks to healthcare workers caused by needle exposure. These solutions typically use a spring-driven mechanism to pull the needle hub back into the core after injection, or employ a dual-chamber structure to house the retraction assembly. This retraction action occurs after injection is complete, unrelated to the drug delivery process, and does not involve real-time optimization of tissue cavity volume during injection. On the other hand, while there are various commercially available micro-injectors specifically designed for ophthalmology, their design focus is often on pneumatic actuation or complex external tubing to achieve ultra-micro-volume injection. These are structurally complex, costly, and similarly do not address the technical path of "needle retraction during injection to release cavity volume."

[0006] In summary, existing technologies lack both a design that allows for simultaneous needle tip retraction during injection and a technical concept that actively releases tissue cavity volume through needle retraction to improve the accuracy of micro-drug administration. Therefore, through beneficial exploration and research, the applicant has found a solution to the aforementioned problems, and the technical solution described below arose from this context. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a micro-injection syringe in which the needle tip can retract synchronously during injection, which can automatically retract the needle tip while injecting the drug solution, thereby gradually freeing up the tissue space occupied by the needle tip during the drug administration process, so that the drug solution can smoothly fill the target area, effectively solving the problems of drug solution spillage and dosage inaccuracy caused by space limitation in micro-injection.

[0008] The technical problem to be solved by this invention can be achieved by the following technical solution:

[0009] A micro-drug delivery syringe with synchronous needle tip retraction during injection includes a syringe outer shell, a core rod, and a needle assembly disposed at the front end of the syringe outer shell, and further includes:

[0010] A connecting rod is disposed inside the syringe jacket; and

[0011] A double-layer gear is rotatably mounted on the syringe jacket, and the double-layer gear is composed of two gears fixedly connected coaxially.

[0012] The core rod is provided with a first rack portion, and the connecting rod is provided with a second rack portion. The first rack portion meshes with one of the gears of the double-layer gear, and the second rack portion meshes with the other gear of the double-layer gear. The two gears rotate in the same direction, so that the core rod and the connecting rod move in opposite directions.

[0013] The needle assembly includes an outer needle and an inner needle that is slidably sleeved inside the outer needle. The rear end of the inner needle is fixedly connected to an inner needle seat, and the inner needle seat is fixedly connected to the front end of the connecting rod.

[0014] A pressing block is fixedly installed on the connecting rod, and a guide groove extending axially is provided on the syringe jacket. The pressing block passes through the guide groove and extends out of the syringe jacket.

[0015] When the core rod is pulled backward, the core rod drives the connecting rod to move forward through the double-layer gear, causing the inner needle to extend out of the outer needle; when the core rod is pushed forward, the core rod drives the connecting rod to move backward through the double-layer gear, causing the inner needle to retract into the outer needle.

[0016] When the pressing block is pressed, the axial movement of the connecting rod is restricted. After the pressing block is released, the connecting rod can move freely axially under the drive of the double-layer gear.

[0017] In a preferred embodiment of the present invention, the pressing block and the connecting rod are integrally formed.

[0018] In a preferred embodiment of the present invention, the first rack portion, the second rack portion, and the two gears of the double-layer gear have the same module, the same pressure angle, and the same tooth profile; the number of teeth of the two gears of the double-layer gear is adapted to the nominal capacity of the syringe and the retraction stroke of the inner needle.

[0019] In a preferred embodiment of the invention, a gear dust cover is further included, which is disposed on the syringe jacket and corresponds to the position of the double-layer gear.

[0020] In a preferred embodiment of the present invention, the rear end of the outer needle is fixedly connected to an outer needle hub, and the outer needle hub is fixedly assembled to the front end of the syringe jacket.

[0021] In a preferred embodiment of the present invention, a first sealing ring is provided between the inner needle seat and the inner needle, and a second sealing ring is provided between the outer needle seat and the outer needle.

[0022] In a preferred embodiment of the invention, a piston is further included, which is disposed at the front end of the core rod.

[0023] In a preferred embodiment of the invention, a scale is further included, which is disposed on the surface of the syringe sheath.

[0024] In a preferred embodiment of the invention, a sheath is further included, which is detachably fitted over the outside of the needle assembly.

[0025] In a preferred embodiment of the present invention, the outer needle is a flat-headed needle.

[0026] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0027] 1. This invention utilizes a linkage transmission mechanism comprised of a core rod, double-layer gears, and a connecting rod to simultaneously retract the inner needle while injecting the medication. This releases the medication from the tissue cavity space occupied by the needle in real time, ensuring accurate deposition of the medication at the target site. This fundamentally solves the problem of medication diffusion and spillage into surrounding tissues caused by the fixed needle occupying the cavity space in traditional syringes. Furthermore, existing retractable syringes retract the needle only after injection, serving solely to prevent needlestick injuries. This invention, however, achieves mechanical coupling between the retraction and injection actions for the first time, realizing "simultaneous injection and retraction," filling the technological gap in "in-injection retraction" within the field of micro-drug administration.

[0028] 2. In this invention, sealing rings are respectively provided between the outer needle hub and the inner needle, and between the outer needle hub and the outer needle, forming a reliable double sealing structure. This effectively prevents leakage of the drug solution during injection, ensures dosage accuracy, and avoids drug solution contamination of the transmission mechanism, thereby improving product durability and safety.

[0029] 3. The design of the pressing block and guide groove in this invention allows the operator to complete the puncture and injection retraction operations with one hand, without the need for an external power source or complex tubing, resulting in low clinical learning costs; the gear and rack linkage transmission is precise and reliable, requiring no additional control. Furthermore, the number of teeth on the double-layer gear can be flexibly selected according to the syringe capacity and inner needle retraction stroke, making it suitable for various micro-injection scenarios such as ophthalmology, dermatology, pediatrics, and small animal experiments.

[0030] 4. When the injection is completed, the inner needle has retracted into the outer needle, and the needle tip is no longer exposed, which effectively avoids the risk of sharp instrument punctures and cross-infection for medical staff, while reducing the difficulty and cost of medical waste disposal. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of a commonly used syringe.

[0033] Figure 2 This is a schematic diagram of the overall assembly of the present invention.

[0034] Figure 3 This is a schematic diagram illustrating the use of the present invention. Detailed Implementation

[0035] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific illustrations.

[0036] like Figure 2 and Figure 3 As shown, the present invention provides a micro-drug delivery syringe in which the needle tip can retract synchronously during injection, including a syringe jacket 100, a core rod 200, and a needle assembly 300 disposed at the front end of the syringe jacket 100.

[0037] The syringe outer casing 100 is a hollow cylindrical body, inside which a connecting rod 400 is installed. The connecting rod 400 extends axially along the syringe outer casing 100 and can slide freely axially inside the syringe outer casing 100. A double-layer gear 500 is rotatably mounted on the syringe outer casing 100. The double-layer gear 500 consists of gears 510 and 520 that are coaxially fixedly connected. Gears 510 and 520 have the same direction of rotation, and the number of teeth can be adapted to the nominal capacity of the syringe and the retraction stroke of the inner needle 320.

[0038] The core rod 200 is provided with a first rack portion 210, and the connecting rod 400 is provided with a second rack portion 410. The first rack portion 210 meshes with one of the gears 510 of the double-layer gear 500, and the second rack portion 410 meshes with the other gear 520 of the double-layer gear 500. The first rack portion 210, the second rack portion 410, and the gears 510 and 520 of the double-layer gear 500 have the same module, the same pressure angle, and a uniform tooth profile to ensure precise and smooth meshing transmission. The number of teeth of the double-layer gear 500 can be flexibly selected according to the nominal capacity of the syringe and the retraction stroke of the inner needle 320 to ensure that the forward distance of the core rod 200 matches the retraction distance of the inner needle 320, achieving synchronous and precise linkage between the injection volume and the needle tip retraction.

[0039] The needle assembly 300 includes an outer needle 310 and an inner needle 320 slidably sleeved within the outer needle 310. An outer needle hub 330 is fixedly connected to the rear end of the outer needle 310 and is fixedly mounted to the front end of the syringe outer sleeve 100. An inner needle hub 340 is fixedly connected to the rear end of the inner needle 320 and is fixedly connected to the front end of the connecting rod 400. Preferably, the outer needle 310 is a flat-tipped needle to suit delicate minimally invasive injection scenarios such as ophthalmology.

[0040] A first sealing ring 350 is provided between the outer needle seat 330 and the outer needle 310, and a second sealing ring 360 is provided between the outer needle seat 330 and the outer needle 310, forming a double sealing structure to effectively prevent the liquid from leaking from the gap between the inner needle 320 and the outer needle 310 during the injection process.

[0041] A pressing block 420 is fixedly mounted on the connecting rod 400, and the pressing block 420 and the connecting rod 400 are preferably integrally molded. A guide groove 110 extending axially is provided on the syringe jacket 100, and the pressing block 420 passes through the guide groove 110 and extends out of the syringe jacket 100. The operator can control the axial movement of the connecting rod 400 by pressing or releasing the pressing block 420.

[0042] A piston 220 is provided at the front end of the plunger 200. The piston 220 is sealed to the inner wall of the syringe jacket 100 for injecting the medication. A scale 120 is provided on the surface of the syringe jacket 100 for easy observation and reading of the medication dosage by the operator. A gear dust cover 130 is also provided on the syringe jacket 100 corresponding to the position of the double-layer gear 500 to protect the double-layer gear 500 from external contamination. A sheath 600 is detachably fitted over the needle assembly 300 to protect the needle when not in use.

[0043] The working process of the micro-drug delivery syringe of the present invention, in which the needle tip can retract synchronously during injection, is as follows:

[0044] I. Preparation and Drug Collection Stage

[0045] The operator first pulls out the sheath 600, grasps the core rod 200, and slowly pulls it backward. At this time, the first rack portion 210 on the core rod 200 drives the double-layer gear 500 to rotate. The double-layer gear 500 then drives the connecting rod 400 forward through the second rack portion 410. The connecting rod 400 drives the inner needle 320 to extend forward through the inner needle seat 340 until the tip of the inner needle 320 is completely exposed at the front end of the outer needle 310. Figure 3 As shown.

[0046] Next, the tip of the inner needle 320 is vertically pierced through the rubber stopper of the vial. After the outer needle 310 is fully embedded inside the rubber stopper, the plunger 200 is slowly pushed to inject an appropriate amount of air into the vial. The vial is then inverted, with the tip of the outer needle 310 remaining below the liquid level. The plunger 200 is then slowly pulled back again, drawing the liquid into the syringe jacket 100. After the liquid is drawn, the plunger 200 is slowly pushed to completely expel any remaining air from inside the syringe.

[0047] II. Injection and puncture stage

[0048] The operator presses down on the pressure block 420 with their finger, temporarily fixing the connecting rod 400 relative to the syringe jacket 100, preventing axial movement. While the pressure block 420 is pressed down, the outer needle 310 and the inner needle 320 are inserted together into the patient's target tissue.

[0049] III. Injection and Synchronous Retraction Phase

[0050] After the puncture is completed, the operator releases the pressure block 420, releasing the constraint on the connecting rod 400, and then begins to push the core rod 200 forward to inject the medication. As the core rod 200 moves forward, its first rack portion 210 drives the double-layer gear 500 to rotate. The double-layer gear 500 then drives the connecting rod 400 to move backward through the second rack portion 410. The connecting rod 400 drives the inner needle 320 to retract backward through the inner needle seat 340, gradually returning to the inside of the outer needle 310.

[0051] Because the two gears of the double-layer gear 500 rotate in the same direction, the core rod 200 and the connecting rod 400 move in opposite directions—that is, when the core rod 200 moves forward, the connecting rod 400 moves backward, and the inner needle 320 retracts synchronously. During the injection process, the tip of the inner needle 320 continuously retracts, gradually freeing up the tissue cavity space originally occupied by the needle tip, allowing the drug solution to smoothly fill the space and concentrate in the target area.

[0052] IV. Final Stage

[0053] When the plunger 200 is fully pushed to the bottom, the inner needle 320 has retracted to a safe position, and the entire medication has been injected into the intended site. The syringe is then withdrawn from the tissue. Since the inner needle 320 has retracted into the outer needle 310, the needle tip is no longer exposed, effectively avoiding the risk of accidental puncture.

[0054] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A micro-drug delivery syringe with synchronous needle tip retraction during injection, comprising a syringe outer shell, a core rod, and a needle assembly disposed at the front end of the syringe outer shell, characterized in that, Also includes: The connecting rod is located inside the syringe jacket; as well as A double-layer gear is rotatably mounted on the syringe jacket, and the double-layer gear is composed of two gears fixedly connected coaxially. The core rod is provided with a first rack portion, and the connecting rod is provided with a second rack portion. The first rack portion meshes with one of the gears of the double-layer gear, and the second rack portion meshes with the other gear of the double-layer gear. The two gears rotate in the same direction, so that the core rod and the connecting rod move in opposite directions. The needle assembly includes an outer needle and an inner needle that is slidably sleeved inside the outer needle. The rear end of the inner needle is fixedly connected to an inner needle seat, and the inner needle seat is fixedly connected to the front end of the connecting rod. A pressing block is fixedly installed on the connecting rod, and a guide groove extending axially is provided on the syringe jacket. The pressing block passes through the guide groove and extends out of the syringe jacket. When the core rod is pulled backward, the core rod drives the connecting rod to move forward through the double-layer gear, causing the inner needle to extend out of the outer needle; when the core rod is pushed forward, the core rod drives the connecting rod to move backward through the double-layer gear, causing the inner needle to retract into the outer needle. When the pressing block is pressed, the axial movement of the connecting rod is restricted. After the pressing block is released, the connecting rod can move freely axially under the drive of the double-layer gear.

2. The micro-drug delivery syringe with synchronous needle tip retraction during injection as described in claim 1, characterized in that, The pressing block and the connecting rod are integrally molded.

3. The micro-drug delivery syringe with synchronous needle tip retraction during injection as described in claim 1, characterized in that, The first rack portion, the second rack portion, and the two gears of the double-layer gear have the same module, the same pressure angle, and the same tooth profile; the number of teeth of the two gears of the double-layer gear is adapted to the nominal capacity of the syringe and the retraction stroke of the inner needle.

4. The micro-drug delivery injector with synchronous needle tip retraction during injection as described in claim 1, characterized in that, It also includes a gear dust cover, which is disposed on the syringe jacket and corresponds to the position of the double-layer gear.

5. The micro-drug delivery syringe with synchronous needle tip retraction during injection as described in claim 1, characterized in that, The outer needle is fixedly connected to the rear end of the outer needle, and the outer needle seat is fixedly assembled to the front end of the syringe jacket.

6. The micro-drug delivery syringe with synchronous needle tip retraction during injection as described in claim 5, characterized in that, A first sealing ring is provided between the inner needle seat and the inner needle, and a second sealing ring is provided between the outer needle seat and the outer needle.

7. The micro-drug delivery syringe with synchronous needle tip retraction during injection as described in claim 1, characterized in that, It also includes a piston, which is disposed at the front end of the core rod.

8. The micro-drug delivery syringe with synchronous needle tip retraction during injection as described in claim 1, characterized in that, It also includes a scale, which is disposed on the surface of the syringe sheath.

9. The micro-drug delivery syringe with synchronous needle tip retraction during injection as described in claim 1, characterized in that, It also includes a sheath that is detachably fitted over the outside of the needle assembly.

10. A micro-drug delivery syringe with synchronous needle tip retraction during injection according to any one of claims 1 to 9, characterized in that, The outer needle is a flat-headed needle.

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