Auto-injector Assembly with Rubber Boot and Dry Needle
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Solution Overview
Problem
Current auto-injector technologies face issues with fragile glass syringes, dimensional challenges, drug stability problems due to needle contact, and high costs associated with bespoke primary containers, as well as limitations with plastic syringes such as inferior oxygen barriers and extractables, which hinder the efficient delivery of large molecule biopharmaceuticals.
Innovation Solution
An auto-injector assembly using industry-standard pre-filled syringes or cartridges with a pierceable septum and a valve system that maintains the needle dry, avoiding direct contact with the drug during storage, and utilizing a spring to keep the medicament under constant pressure for gentle injection and leak detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass pre-filled syringes are used as primary containers, then they provide good oxygen barrier properties and are chemically inert, but they are fragile and not well suited to use in spring-driven auto-injector devices
Solution Approach 1:
A rubber boot is introduced as an intermediary component between the spring mechanism and the glass syringe. The boot acts as a cushioning element that absorbs the impact force when the spring engages, preventing direct transmission of shock to the fragile glass container while still enabling effective drug delivery.
Solution Approach 2:
The rubber boot is pre-installed on the syringe before the spring engagement, providing advance protection against impact damage. This cushioning element is positioned in anticipation of the spring's engagement force, ensuring the glass syringe is protected before the actual impact occurs.
2Stability of the object's composition
If glass pre-filled syringes are used, then they provide chemical inertness, but dimensional control during manufacture is difficult resulting in broad syringe tolerances
Solution Approach 1:
The auto-injector device incorporates flexible and adjustable components that can adapt to variations in syringe dimensions. The spring mechanism and housing are designed with tolerances that accommodate the broad syringe variations, allowing the system to function effectively across the range of dimensional variations without requiring precise manufacturing control.
3Ease of operation
If the drug is contained within a pre-filled syringe in contact with needle metal during prolonged storage, then the injection can be delivered, but drug stability problems occur
Solution Approach 1:
The needle is extracted or separated from the syringe chamber during storage. The needle remains in a protected, non-contact state with the drug, eliminating the source of metal-induced degradation. The needle is only introduced into contact with the drug at the moment of injection when the syringe is activated.
4Stability of the object's composition
If a rubber cap or boot is used to close the opening at the needle tip during storage, then needle metal contact is prevented, but application or removal of the rubber cap can lead to needle damage
Solution Approach 1:
The rubber boot serves as a protective cushion that envelops the needle during storage and handling. This soft protective layer prevents mechanical damage to the needle while maintaining the needle's readiness for injection. The boot is designed to be applied and removed without exerting damaging forces on the needle.
5Strength
If plastic cartridges or pre-filled syringes are used as primary containers, then they avoid fragility issues, but they need to be manufactured in clear plastic with high oxygen barrier properties which are always inferior to glass and are expensive
Solution Approach 1:
The device employs a composite construction where the syringe chamber can be made of durable plastic material, while the rubber boot and sealing components provide the necessary oxygen and moisture barrier properties. This combination leverages the advantages of both materials: the durability of plastic and the barrier properties of rubber/elastomeric materials.
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
Enables the injection of larger volumes with reduced risk of container breakage, improved drug stability, and cost-effective production by using standard filling procedures and materials, while minimizing needle damage and ensuring sterility.
Implementation Method 1
utilizing a spring to keep the medicament under constant pressure for gentle injection and leak detection
Data Source
AI summary
An auto-injector assembly comprises a medicament container defining a substantially cylindrical chamber containing a liquid medicament. A proximal end of the chamber is closed by a piston and a distal end of the chamber is closed by a seal spanning an opening. A biasing means, such as a spring, is coupled to the piston and acts to bias the piston towards the seal, thereby pressurizing the liquid medicament. The assembly also comprises a hypodermic needle and a removable needle cap for maintaining the hypodermic needle in sterile conditions until use. A means for establishes fluid communication between the chamber and the hypodermic needle such that the pressurized liquid medicament is automatically delivered through the hypodermic needle when communication has been established.