Automatic Injector Anti-Coring Needle Design
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Solution Overview
Problem
Automatic injectors face the issue of needle coring, where the needle dislodges material from the seal, potentially blocking the needle orifice or being forced into the individual's flesh, which is not adequately addressed in existing technologies.
Innovation Solution
The design incorporates a housing with a seal structure, a cartridge containing a medicament, and a needle that is projectable through the seal, with a plunger driven by a releasable energy source. The cartridge features an increased friction region to slow the needle's motion and a damping structure to reduce acceleration, and the needle may have a curved tip or be coated with Parylene to minimize coring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the needle is forced through the seal at high speed, then the injection operation is completed quickly, but the needle may core out material from the seal and block the needle orifice
Solution Approach 1:
A curved guide surface is provided on the seal between the needle and the cartridge. This guide surface acts as an intermediary element that redirects the needle's motion, causing it to curve away from the seal material and preventing coring while maintaining injection speed
Solution Approach 2:
The guide surface on the seal is curved rather than flat. This curvature changes the needle's trajectory as it penetrates the seal, directing it away from the seal material and preventing coring. The curved geometry is specifically designed to redirect the needle without significantly increasing injection time
2Productivity
If the needle is forced through the seal at high speed, then the injection procedure is efficient, but seal material may be dislodged and forced into the individual's flesh
Solution Approach 1:
The curved guide surface serves as a mediator that controls the needle's path through the seal. By redirecting the needle away from the seal material, it prevents dislodged material from being forced into the individual's flesh while maintaining injection efficiency
Solution Approach 2:
The curved guide surface on the seal redirects the needle's trajectory, causing it to curve away from dislodged seal material. This curvature prevents the harmful effect of injecting seal material into the individual while preserving injection speed and efficiency
3Reliability
If the needle is slowed down during seal penetration, then coring is reduced, but the injection operation takes longer
Solution Approach 1:
The curved guide surface reduces coring by redirecting the needle away from seal material during penetration. The curvature is designed to provide this protective effect without significantly increasing the time required for needle penetration and injection
Solution Approach 2:
The guide surface changes the directional parameters of needle motion during seal penetration. By altering the needle's trajectory through curvature, it reduces coring while maintaining acceptable injection timing through optimized geometric design
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces or eliminates needle coring, ensuring efficient and safe injection by controlling the needle's speed and interaction with the seal, thereby minimizing the formation of cores and their size.
Implementation Method 1
The cartridge has an increased friction region so as to slow the motion of the needle as the forward end of the needle travels through the seal
Implementation Method 2
the needle may have a curved tip or be coated with Parylene to minimize coring
Data Source
AI summary
In one embodiment, an automatic injector comprises a cartridge adapted to contain a charge of medicament, a seal structure disposed toward a forward end of the cartridge, a plunger normally disposed in a generally rearward end of the cartridge and movable through the cartridge toward a generally forward end thereof in response to an actuating procedure. The movable plunger rearwardly confines the medicament within the cartridge. A needle normally disposed in communication with the medicament container provides a passage in which the medicament is released into an individual's flesh in response to an actuating procedure projecting the needle into the flesh of the individual. The cartridge having an increased friction region so as to slow the motion of the plunger when the forward end of the needle travels through the seal in order to eliminate coring.