Injection Needle Extraction Mechanism with Compact Nested Plunger
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Solution Overview
Problem
Existing injection devices for implantable chambers are cumbersome and prone to handling errors due to their substantial footprint and the need for significant force to remove the needle, which can cause discomfort and jolts to the patient.
Innovation Solution
The injection device features a plunger with an outer and inner part that can move between retracted and deployed configurations, utilizing a flexible interlocking mechanism with snap-in tabs and ramps to securely lock the plunger in place, reducing the device's size and minimizing the force required for needle extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the extraction mechanism is hinged to the needle support and retained in an extended position by a flexible interlocking mechanism, then the device can be compact when not in use, but the device still has a substantial footprint and may cause handling errors
Solution Approach 1:
The plunger is divided into an outer part and an inner part that can move relative to each other. The inner part can be inserted into or removed from the outer part, allowing the extraction mechanism to be segmented into compact and deployed states, thereby reducing the device footprint while maintaining functionality
Solution Approach 2:
The inner part of the plunger is nested within the outer part in the retracted configuration, similar to nested dolls. This nesting allows the extraction mechanism to occupy minimal space when not in use, reducing the substantial footprint issue while remaining ready for deployment when needed
2Productivity
If a significant pulling force is exerted on the needle to remove it from the implantable chamber, then the needle can be extracted, but the patient suffers from forces exerted on the skin
Solution Approach 1:
The extraction mechanism performs preliminary action by gradually swallowing the needle into the plunger during extraction. This step-by-step extraction process distributes the pulling force over time and reduces the peak force required, making needle removal more efficient while minimizing patient discomfort
Solution Approach 2:
The plunger acts as an intermediary between the practitioner's pulling force and the needle. Instead of directly pulling the needle which causes sharp forces on the skin, the plunger gradually engages and extracts the needle, mediating the force application to reduce patient discomfort while maintaining extraction efficiency
Data Source
AI summary
Disclosed is an injection device including: —a needle support; —an injection needle integral with the needle support and having a free end arranged away from the needle support; and —a needle extraction mechanism including a base connected to the needle support and a plunger movable relative to the base between a needle use position and a needle extraction position. The base is movable relative to the needle support between an inactive position of the extraction mechanism and an active position of the extraction mechanism. The plunger includes an outer member and an inner member, movable relative to the outer member, from a retracted plunger configuration to a deployed plunger configuration wherein the plunger length is greater than in the retracted configuration.