Injector Force Lock-Out and Rate-Limiting Mechanism
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Solution Overview
Problem
Current pen-type injection systems face challenges in delivering medicaments to intradermal tissue layers due to high backpressure resistance, leading to potential leakage and inaccurate depth and rate of injection, which can result in 'jetting' of the medicament past the desired tissue depth.
Innovation Solution
An injection device equipped with a lock-out mechanism that ensures proper skin contact and a rate-limiting mechanism to control the delivery rate, preventing leakage by locking the injection mechanism until a specified force is applied and maintaining a controlled delivery rate via a spring mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pen-type injection systems are used to deliver medicaments to intradermal tissue layers, then the injection can be performed with standard equipment, but high backpressure resistance causes leakage and inaccurate depth and rate of injection
Solution Approach 1:
The lock-out mechanism is engaged before injection to pre-set and maintain a precise injection depth, preventing the plunger from advancing beyond the predetermined depth. This preliminary action ensures accurate intradermal delivery while compensating for backpressure variations during injection.
Solution Approach 2:
The device incorporates adjustable parameters including injection depth (via lock-out positioning) and injection rate (via flow control). These parameter changes allow optimization of injection conditions to overcome backpressure resistance and prevent leakage while maintaining accuracy.
2Productivity
If greater force or pressure is exerted on the injector device actuator to overcome backpressure resistance, then injection into intradermal layers can be achieved, but the medicament may be jetted past the desired tissue depth
Solution Approach 1:
The lock-out mechanism is engaged before injection to pre-set and maintain a precise injection depth, preventing the plunger from advancing beyond the predetermined depth. This preliminary action ensures accurate intradermal delivery while compensating for backpressure variations during injection.
Solution Approach 2:
The device provides visual feedback indicators showing the locked-out depth position and injection progress. This feedback allows the user to monitor and control the injection process, ensuring the medicament is delivered to the correct depth without jetting past the desired tissue layer.
3Productivity
If the injection rate is increased to overcome backpressure resistance, then medicament delivery can be completed faster, but leakage of medicament occurs
Solution Approach 1:
The device incorporates adjustable parameters including injection depth (via lock-out positioning) and injection rate (via flow control). These parameter changes allow optimization of injection conditions to overcome backpressure resistance and prevent leakage while maintaining accuracy.
Solution Approach 2:
The injection process is controlled to occur in a regulated manner through the lock-out mechanism and flow control, creating a periodic or controlled action rather than continuous uncontrolled flow. This prevents leakage while maintaining efficient delivery.
4Manufacturing precision
If a lock-out mechanism is added to ensure proper skin contact and control injection depth, then injection accuracy is improved, but device complexity increases
Solution Approach 1:
The injection device is segmented into distinct functional components: a lock-out mechanism for depth control, a flow control mechanism for rate regulation, and a standard injection system. This segmentation allows each component to perform its specific function independently, achieving precise control while maintaining modularity.
Solution Approach 2:
The lock-out mechanism acts as an intermediary between the user's actuation force and the plunger movement. It mediates the injection process by controlling and limiting plunger advancement to a predetermined depth, ensuring accurate intradermal delivery without requiring complex active control systems.
5Manufacturing precision
If a rate-limiting mechanism is added to control delivery rate and prevent leakage, then injection precision is improved, but device complexity increases
Solution Approach 1:
The device incorporates adjustable parameters including injection depth (via lock-out positioning) and injection rate (via flow control). These parameter changes allow optimization of injection conditions to overcome backpressure resistance and prevent leakage while maintaining accuracy.
Solution Approach 2:
The flow control mechanism is localized to the injection pathway, providing rate limitation specifically at the point where medicament flows from the reservoir through the needle. This localized control achieves precise rate management without requiring complex system-wide control mechanisms.
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 effectively minimizes medicament leakage and ensures accurate depth and rate of injection, preventing 'jetting' and ensuring efficient delivery to the intradermal tissue layer.
Implementation Method 1
maintaining a controlled delivery rate via a spring mechanism
Implementation Method 2
locking the injection mechanism until a specified force is applied
Data Source
AI summary
An injectable substance delivery device comprising a pen device body, a cartridge, a plunger, a drive mechanism, and at least one of a lock-out mechanism and a rate-limiting mechanism. The lock-out mechanism is provided through a ratchet engagement between the body and the plunger to restrict plunger movement and to ensure that the required needle puncture depth is realized prior to injection by locking out the injection mechanism from advancing until a specified force is applied to the skin. A rate-limiting mechanism is also provided through a user compressed plunger drive spring to ensure that a specific rate of injection is realized during the injection of a medicament.