Shape Memory Spring Injector Drive for Metered Drug Delivery
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Solution Overview
Problem
There is a need for automatic injection devices that are compact, easy to handle, and discrete for extended wear, with features that allow for easy replacement of drug containers while minimizing contamination risks, and that provide controlled delivery of pharmaceutical products.
Innovation Solution
An automatic injection device with a passive drive system utilizing a shape memory spring to move a plunger within a drug container, allowing for precise control and metered delivery of pharmaceutical products, featuring a shape memory alloy spring that changes shape to push the plunger and includes a mechanical restrictor for regulated delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a shape memory spring is used in the drive system, then the device achieves compact form factor with high compression ratio, but the device complexity increases due to the specialized material and mechanism
Solution Approach 1:
The patent utilizes shape memory alloy's ability to change physical parameters (shape, length) in response to temperature changes. The spring transitions between compressed and extended states through thermal parameter changes, enabling compact storage and controlled delivery without complex mechanical linkages
Solution Approach 2:
The patent replaces traditional complex mechanical drive systems (gears, linkages, motors) with a shape memory spring that uses thermal-mechanical coupling. This substitution eliminates multiple moving parts while achieving the same plunger actuation function through material property changes
2Ease of operation
If the plunger is moved automatically by a drive system, then the ease of operation is improved for self-administration, but the reliability decreases due to potential contamination risks
Solution Approach 1:
The patent divides the injection device into separable components: a reusable outer housing containing the drive system and a disposable inner cartridge containing the pharmaceutical product and plunger. This segmentation allows the sterile cartridge to be replaced without handling the non-sterile drive mechanism, maintaining sterility while enabling easy operation
Solution Approach 2:
The patent employs a disposable cartridge system where the inner container holding the pharmaceutical product is designed for single use. After one injection, the entire cartridge is discarded, eliminating contamination risks associated with repeated use and simplifying operation for patients
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 achieves precise control over plunger movement and pharmaceutical delivery, maintaining a compact form factor with a high compression ratio, ensuring easy replacement of drug containers and minimizing contamination risks, while providing controlled and efficient delivery of medications.
Implementation Method 1
The movable element includes a shape memory alloy and is configured to change shape to move the plunger
Data Source
AI summary
An automatic injection device has an insertion needle configured to be inserted into a patient and a drug container which contains a pharmaceutical product and includes a plunger. The automatic injection device also has a fluid path which fluidly connects the drug container to the insertion needle, and a drive system configured to cause linear movement of the plunger to force the pharmaceutical product into the fluid path. The passive drive system has a movable element. The movable element has a shape memory alloy and is configured to change shape to move the plunger.