Fluid Injector Microneedle Depth Control via Rotational Mechanism
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Solution Overview
Problem
Existing fluid injectors using multi-microneedle devices face challenges in efficiently and reliably injecting a desired amount of fluid into skin tissue during intradermal injections, often resulting in fluid leakage or prolonged injection times due to the limitations in controlling the depth and force of microneedle penetration.
Innovation Solution
An operation tool with a selective movement mechanism that moves the fluid injector between two protruding positions, utilizing a rotational-linear movement conversion mechanism to adjust the depth of microneedle penetration, allowing for precise control of microneedle protrusion and reducing the pressing force on the skin, enabling efficient and complete fluid injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the microneedle protrusion depth is increased to ensure complete fluid injection into skin tissue, then the injection reliability is improved, but the risk of fluid leakage and tissue damage increases
Solution Approach 1:
The microneedle assembly is designed with dynamic movement capability, allowing the microneedles to move between a first position (protruding deeper into skin tissue for reliable injection) and a second position (retracted to minimize leakage). This dynamic adjustment resolves the contradiction by enabling the system to optimize needle depth based on operational requirements.
Solution Approach 2:
The invention changes the parameter of microneedle protrusion depth from a fixed value to a variable parameter that can be adjusted between two distinct positions. This parameter change allows the system to adapt the needle depth to different operational phases (insertion/injection vs. retraction), thereby improving reliability while minimizing harmful fluid leakage.
2Reliability
If the pressing force on the skin is increased to ensure complete fluid injection, then the injection completeness is improved, but the pain and tissue damage increase
Solution Approach 1:
The movable microneedle assembly allows the system to apply optimal pressing force dynamically. During injection, the microneedles are positioned to penetrate skin tissue effectively; after injection, they can be retracted to reduce pressing force and minimize tissue damage and pain.
Solution Approach 2:
The injection process is segmented into distinct phases: insertion phase (with deeper microneedle protrusion for reliable fluid delivery), injection phase (with controlled pressing force), and retraction phase (with reduced pressing force to minimize damage). This segmentation allows optimization of pressing force for each phase, improving completeness while reducing harm.
3Productivity
If the microneedle array density is increased to reduce injection time, then the productivity is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The microneedle array is segmented into multiple individual microneedles arranged in a pattern, allowing parallel fluid injection through multiple channels simultaneously. This segmentation enables rapid injection (high productivity) while maintaining a manageable device structure, as each microneedle operates independently within the array.
Solution Approach 2:
The microneedle array structure serves multiple functions: it provides multiple injection channels for rapid fluid delivery, maintains structural integrity for easy handling, and enables the movable assembly mechanism. This multi-functionality achieves high productivity without proportionally increasing device complexity.
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 tool allows for reliable and rapid injection of the desired amount of fluid into the skin tissue, minimizing leakage and reducing the time required for intradermal injections, while maintaining a simple and cost-effective configuration.
Implementation Method 1
a rotational-linear movement conversion mechanism which is interposed between the outer cylinder and the fluid injector, and moves the fluid injector between the first protruding position and the second protruding position along a longitudinal center line of the outer cylinder based on a direction and an amount of rotation of the outer cylinder relative to the fluid injector
Data Source
AI summary
An operation tool for a fluid injector includes a selective movement mechanism which moves the fluid injector between a first protruding position and a second protruding position in a housing of an outer cylinder. When the fluid injector is at the first protruding position, microneedles of a multi-microneedle device are protruded out to a first distance from the first open end. When the fluid injector is at the second protruding position to discharge a fluid via the microneedles, the microneedles are protruded out to a second distance from the first open end, which is shorter than the first distance. The selective movement mechanism includes a rotational-linear movement conversion mechanism which moves the fluid injector between the first and second protruding positions along a longitudinal center line of the outer cylinder based on a direction and an amount of rotation of the outer cylinder relative to the fluid injector.