Modular Injection Device With Dynamic Stopper Rate Control
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Solution Overview
Problem
Existing injection devices face challenges in delivering precise and controlled delivery of shape adaptable materials, particularly in clinical settings, where human factors and material properties require delicate handling to ensure the intended function is not subverted by rapid changes in material properties or administration speed.
Innovation Solution
An injection device with a junction component, reservoir, and actuation mechanism using a spring-loaded stopper system that controls ejection through an injection port, allowing for precise delivery of shape adaptable materials, including non-Newtonian substances, with features like a pneumatic force seal and modular design for user-friendly operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional injection device is used to deliver shape adaptable materials, then the injection can be performed quickly, but the material properties may change rapidly causing loss of control over injection precision and placement accuracy
Solution Approach 1:
The stopper is designed with dynamic properties that allow it to respond to material resistance forces. As the stopper advances into the reservoir, it experiences varying friction and material resistance, which dynamically adjusts the injection rate. This dynamic response enables precise control of shape adaptable materials that change properties during injection, maintaining placement accuracy while allowing rapid delivery when material properties are stable.
Solution Approach 2:
The stopper's physical parameters (friction coefficient, compressibility, radial expansion characteristics) are specifically selected and adjustable to match the rheological properties of different shape adaptable materials. By changing the stopper's parameters to correspond with material viscosity and resistance characteristics, the system maintains precise control over injection placement even as material properties evolve during the injection process.
2Reliability
If the stopper is made with tight interference fit to seal the reservoir, then sealing reliability is improved, but the force required to advance the stopper increases causing difficulty in operation
Solution Approach 1:
The stopper's friction parameter with the reservoir wall is specifically optimized to provide adequate sealing while maintaining acceptable actuation forces. The interference fit is designed with controlled clearance and surface characteristics that ensure reliable sealing of shape adaptable materials without creating excessive resistance that would difficult manual or mechanical actuation.
Solution Approach 2:
The stopper exhibits dynamic radial expansion and contraction during actuation. As axial force is applied to advance the stopper, it dynamically adjusts its radial dimension, temporarily reducing interference fit to lower actuation forces while maintaining sealing integrity. This dynamic behavior allows easy operation while preserving sealing reliability throughout the injection process.
3Device complexity
If a pre-filled reservoir system is used for single-use applications, then device complexity is reduced, but the ability to control injection rate for materials with varying properties is limited
Solution Approach 1:
The stopper is designed to automatically self-regulate the injection rate based on material resistance forces without requiring external control mechanisms. As the stopper advances through the reservoir, it naturally responds to changes in material viscosity and resistance, self-adjusting the injection rate to maintain optimal delivery of shape adaptable materials. This self-service capability provides rate control in a simple pre-filled reservoir system.
Solution Approach 2:
The system incorporates passive feedback through the stopper's interaction with the material being injected. The stopper's motion is continuously influenced by material resistance forces, creating a feedback loop where injection rate automatically adjusts based on real-time material properties. This feedback mechanism enables precise rate control for shape adaptable materials while maintaining device structural simplicity.
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 precise and efficient delivery of shape adaptable materials, ensuring the intended function is maintained by controlling the injection rate and volume, suitable for single-use and low-volume applications, particularly in clinical settings.
Implementation Method 1
Extension of the spring can impart a force to a rear portion of the stopper that radially expands the stopper thereby increasing an interference fit with an inner surface of the reservoir
Implementation Method 2
Extension of the spring can impart a force to a rear portion of the stopper that radially contracts the stopper thereby reducing an interference fit with an inner surface of the reservoir
Implementation Method 3
The spring can provide an injection force at about 30% compression of the spring or less that exceeds a resistance force experienced by the stopper during translation within the reservoir
Data Source
AI summary
Described herein is a generalized injection device for delivering formulations of various mechanical properties to precise locations. Of particular interest is the manifestation intended for the application of a thermally responsive hydrogel to the tear duct for the purpose of occlusion, as a treatment for symptoms associated with dry eye syndrome. Further, a modular solution to the need for an injection device across a variety of applications, mechanism, and physical considerations is provided. This disclosure provides examples of methods for precise injection of low volumes, moisture retention in pre-filled injection devices, and actuation for automatic or manual injection, to name a few.