Auto-Injector Rotating Collar for Skin Pressure Damping
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Solution Overview
Problem
Existing injection devices, both manual and auto-injectors, pose challenges such as the risk of underdosing, high injection forces, hand trembling, and accidental needle sticks, particularly for users with dexterity issues or elderly individuals.
Innovation Solution
An auto-injector design featuring a rotating collar to dampen the pressure exerted on the skin during injection, a lateral release element to prevent accidental activation, and safety mechanisms to ensure proper placement and needle safety, utilizing a single drive means for multiple functions including needle insertion, medicament expulsion, and needle retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single drive means is used for multiple functions (needle insertion, medicament expulsion, needle retraction), then device complexity is reduced, but control precision over each individual function deteriorates
Solution Approach 1:
The spring-driven drive means is designed to perform multiple functions: inserting the needle into the patient, expelling the medicament through the pre-filled syringe, and retracting the needle after injection. This single multi-functional mechanism reduces device complexity while maintaining adequate control through careful mechanical design of the drive means engagement and disengagement points.
Solution Approach 2:
The injection process is segmented into distinct phases (needle insertion, medicament expulsion, needle retraction) that are sequentially activated by the single drive means. The drive means is designed to engage different components at different stages, with the plunger being released after a predetermined time period to expel the medicament, and the needle shroud being retracted in a final phase.
2Reliability
If the needle shroud is pushed against the skin with high force to ensure proper placement, then placement reliability is improved, but the risk of bruising and skin injury increases
Solution Approach 1:
The rotating collar is designed to rotate between 0-360 degrees during needle shroud advancement, creating a dampening effect that cushions the force applied to the skin. This rotational movement dissipates energy and reduces peak forces, preventing bruising while maintaining adequate placement force. The collar acts as a mechanical cushion that transforms linear pushing force into rotational motion.
Solution Approach 2:
The rotating collar introduces dynamic motion to what would otherwise be a static pushing action. As the needle shroud is advanced, the collar rotates freely, converting part of the linear force into rotational kinetic energy. This dynamic element reduces the static force transmitted to the skin, lowering the risk of injury while maintaining placement reliability.
3Device complexity
If manual button/plunger devices are used, then device simplicity is improved, but the risk of underdosing and incomplete injection increases
Solution Approach 1:
The auto-injector is designed to perform the injection function automatically without requiring continuous user intervention. The spring-driven drive means self-actuates to insert the needle, and after a predetermined time period, automatically releases the plunger to expel the medicament. The system serves itself by using the stored elastic energy in the spring to complete the injection sequence, eliminating the need for manual button pressing and ensuring complete dose delivery.
Solution Approach 2:
The spring is pre-loaded with elastic energy before use, and the plunger is pre-positioned in a locked state. Upon activation, the drive means automatically executes the injection sequence without requiring the user to manually press a button throughout the process. The predetermined time period allows the needle to be properly positioned before automatic medicament expulsion begins, ensuring reliable dose delivery.
4Ease of operation
If the release element is positioned at the distal end for easy access, then ease of operation is improved, but the risk of accidental activation increases
Solution Approach 1:
The release element is positioned laterally on the housing rather than at the distal end, creating an asymmetric configuration that reduces the risk of accidental activation. This lateral positioning requires intentional user action to access the release element, as it is not in the natural path of movement during normal handling. The asymmetric placement maintains ease of operation for intended use while significantly reducing accidental activation risk.
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
Reduces the risk of bruising and accidental needle sticks while ensuring proper dose delivery and safe needle retraction, making the device intuitive and cost-effective for single-use applications.
Implementation Method 1
The rotating collar engages the needle shroud in a manner that forces the rotating collar to rotate within the housing when the needle shroud is translated in the proximal direction
Implementation Method 2
a releasable drive means arranged within the housing that is capable of, upon release, translating the needle shroud in a proximal direction
Data Source
AI summary
According to the invention, an auto-injector for administering a dose of a liquid medicament (M) comprises of a substantially cylindrical housing arranged to contain a pre-filled syringe filled with the medicament (M), a needle shroud slibably arranged with respect to the housing and adapted to rest on the skin of a patient receiving an injection, a releasable drive means arranged within the housing that is capable of, upon release, translating the needle shroud in a proximal direction (P) towards a safe position (PS) and a rotating collar rotatably arranged within the housing. The needle shroud in the safe position (PS) surrounds the injection needle after the injection has been carried out. The rotating collar engages the needle shroud in a manner that forces the rotating collar to rotate within the housing when the needle shroud is translated in the proximal direction (P).