Needle-Assisted Injector Trigger Mechanism for Reduced Firing Force
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Solution Overview
Problem
Existing injection devices face issues with accidental firing due to mishandling, constrained design dimensions, and binding of triggering components, leading to potential harm and design limitations.
Innovation Solution
A needle-assisted jet injector with a trigger member, ram assembly, and energy source configured for jet injecting medicament, featuring a skin-contacting member for proximal movement to initiate firing, a retractable needle guard, and a locking mechanism to prevent reuse after dispensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a trigger mechanism is used to store and release kinetic energy for injection, then the injection force is improved, but the risk of accidental firing increases
Solution Approach 1:
The trigger mechanism is segmented into multiple functional components: a trigger member for user actuation, a blocking member that prevents premature firing, and a latch member that maintains the blocked state. This segmentation allows each component to perform its specific function, ensuring the trigger only fires when properly actuated by the user while preventing accidental activation during handling or storage.
Solution Approach 2:
The blocking member acts as an intermediary between the trigger member and the energy storage mechanism. It physically intervenes to prevent the trigger from releasing kinetic energy unless the user deliberately actuates the complete trigger assembly, thereby mediating between user intent and potential accidental firing.
2Volume of moving object
If the device dimensions are constrained, then the device portability is improved, but the triggering components bind and fail to operate
Solution Approach 1:
The latch member utilizes rotational movement in a different dimensional plane to achieve the firing action. Instead of requiring linear displacement that would consume more volume, the latch rotates about an axis, allowing the triggering mechanism to operate within compact dimensions while maintaining full functionality.
Solution Approach 2:
The latch member is designed with dynamic characteristics that allow it to rotate freely during normal operation but become constrained when engaged with the blocking member. This dynamic design enables the mechanism to adapt its movement characteristics based on the operational state, maintaining ease of operation within limited space.
3Productivity
If high pressure is used to inject medicament through a needle, then the injection speed is improved, but the risk of tissue damage and accidental firing increases
Solution Approach 1:
The device performs preliminary actions to ensure safe operation: the blocking member is pre-positioned to prevent accidental firing, the needle guard is pre-configured to protect against unintended needle movement, and the trigger mechanism is pre-designed with multiple safety interlocks. These preliminary safety measures allow the device to achieve high injection speeds without increasing harmful effects.
Solution Approach 2:
The needle guard serves as an intermediary protective element between the high-pressure injection system and the external environment. It mediates the interaction by containing the needle and preventing accidental contact, thereby allowing high-pressure injection to proceed safely.
4Reliability
If a needle guard is added to protect against accidental needle exposure, then the safety is improved, but the device complexity increases
Solution Approach 1:
The needle guard is merged with the existing trigger mechanism components. The blocking member that already exists in the trigger assembly also serves as part of the needle guard structure, combining multiple safety functions into a single integrated component rather than adding a completely separate mechanism.
Solution Approach 2:
The blocking member performs multiple functions: it acts as part of the trigger mechanism, provides a safety interlock to prevent accidental firing, and contributes to the needle guard structure. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while improving safety.
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
The device ensures safe and efficient medicament delivery with reduced accidental firing risk, accommodates various medicament types, and allows self-administration by non-trained individuals, enhancing usability and safety.
Implementation Method 1
The pressure applied to the medicament is preferably higher than that of a traditional auto-injector or the like, causing the medicament to penetrate the skin and be dispersed into the tissue or injected in the tissue below the skin
Implementation Method 2
needle-assisted jet injectors have also been developed with higher injection forces that utilize a needle to initially penetrate the skin allowing a range of needle insertion depth
Data Source
AI summary
An injector includes a trigger mechanism including: a trigger member disposed about an axis having an aperture and a protrusion, and a ram assembly having a ram configured to pressurize a medicament container for expelling a medicament therefrom, the ram assembly further having a trigger engagement member configured to engage the aperture of the trigger member when the trigger member is in a pre-firing condition; an energy source associated with the ram for powering the ram to expel the medicament; and a user-operable firing-initiation member having an aperture engaged with the protrusion of the trigger member and operable for causing an axial translation of the trigger member in a proximal direction from the pre-firing condition to a firing condition in which the trigger engagement member is released from the retaining portion to allow the energy source to fire the ram.