Segmented Latch Reduces Needle Retraction Force
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Solution Overview
Problem
Existing needle retraction devices require excessive force for single-handed operation, posing a challenge for medical staff with weaker hands and necessitating a reduction in the force needed to trigger needle retraction for smoother operation.
Innovation Solution
The device features a hollow body with radially outward and inward openings in the latches, allowing each latch to connect only at its side edges, reducing the force required for latch deflection by enabling a twisting motion instead of bending, which decreases the overall force needed for needle retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the latches are formed as solid integral structures with traditional bending mechanisms, then the latches provide sufficient strength and stiffness for needle hub retention, but the force required to deflect the latches for needle retraction becomes unacceptably high
Solution Approach 1:
The latch structure is segmented by introducing radial openings that divide the solid latch into multiple sections. These openings create a lattice-like configuration where the latch material is divided into discrete segments connected by thin walls, allowing the latch to twist rather than bend during retraction, thereby reducing the force required while maintaining structural integrity for needle retention.
Solution Approach 2:
The invention changes the structural parameter of the latch from a solid continuous form to a lattice structure with radial openings. This parameter change transforms the mechanical behavior of the latch during deflection, enabling it to twist along its length rather than bend, which significantly reduces the retraction force while preserving the strength needed for initial needle hub retention.
2Reliability
If the latches are made with sufficient strength for needle hub retention, then reliable needle mounting is achieved, but the operation becomes difficult for medical staff with weaker hands
Solution Approach 1:
By segmenting the latch structure through radial openings, the invention creates a configuration that maintains reliability for needle retention while reducing the force needed for retraction. The segmented lattice structure allows the latch to flex and twist during retraction, making the device operable by medical staff with weaker hands while still providing secure needle mounting during use.
Solution Approach 2:
The structural parameter change from solid to lattice configuration with radial openings enables the latch to achieve both reliability for needle retention and ease of operation. The modified geometry allows sufficient strength for secure mounting while requiring significantly less force for the retraction action, facilitating single-handed operation.
3Ease of manufacture
If traditional solid latch structures are used, then manufacturing is straightforward, but the retraction mechanism requires excessively high force
Solution Approach 1:
The radial openings that segment the latch structure can be efficiently created during the moulding process, maintaining ease of manufacture while fundamentally changing the mechanical behavior of the latch. The segmentation enables the latch to twist during retraction, reducing the required force without adding complex manufacturing steps.
Solution Approach 2:
The invention modifies the structural parameter of the latch by introducing radial openings during moulding, which transforms the solid structure into a lattice configuration. This parameter change reduces the retraction force requirement while the moulding process itself remains relatively simple, preserving ease of manufacture.
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 design reduces the force required for needle retraction by up to 75% compared to traditional bending mechanisms, facilitating easier single-handed operation and safer needle handling.
Implementation Method 1
mounting a needle hub against bias of a spring
Implementation Method 2
the spring, which drives the hub and an attached needle assembly rearwards into the interior of the plunger
Implementation Method 3
reducing the force required for latch deflection by enabling a twisting motion instead of bending
Data Source
AI summary
A needle retraction medical device including a hollow body (10) and a plunger (20). The hollow body (10) has a first end (11) provided with a needle mounting hub (13) and a plurality of releasable latches (15) holding the needle mounting hub (13) against spring (14) bias. The latches (15) are formed integrally with the hollow body (10) and project longitudinally inside the hollow body (10) from a proximal end at or adjacent the first end (11) of the hollow body (10) to a free end. A respective opening (35) is provided in the body (10) radially inwards of each of the latches (15). The plunger (20) has a forward end insertable into the body (10) from a second end thereof, a hollow interior and a closed rear end. The plunger front end is operable, upon insertion of the plunger (20) into the body (10), to deflect the latches (15) radially outwards and thereby release the needle mounting hub (13) from the latches (15) so that the hub (13) together with the needle mounted thereby retract under spring action into the hollow interior of the plunger (20). A respective opening (30) is also provided in the hollow body (10) radially outwards of at least some of the latches (15) so that each such latch (15) connects to the material of the body (10) only at each side of its proximal end.