Filtering Needle Seal Plug Blocks Reinsertion After Use
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Solution Overview
Problem
Existing filter needle assemblies intended for single use are prone to reuse, posing a risk of administering contaminated liquid payloads due to the lack of mechanisms to prevent reinsertion of the hollow needle into the filtering needle cap.
Innovation Solution
A filtering needle assembly design that includes a seal plug which, when the hollow needle is removed, prevents reliable reinsertion by forming a seal around the needle's distal portion, ensuring the assembly cannot be used for a second quantity of liquid payload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter needle assembly is designed for single use without additional prevention mechanisms, then the device complexity is low and ease of manufacture is high, but the reliability is compromised due to potential reuse and contamination risk
Solution Approach 1:
The seal plug is pre-positioned within the filter needle cap body in a held state during manufacturing. This preliminary action ensures that when the hollow needle is removed after use, the seal plug automatically moves to seal the lumen, preventing reuse. The holding mechanism (such as a detent or friction fit) maintains the seal plug in its initial position until the needle is withdrawn, at which point the seal plug is freed to move and seal the opening.
Solution Approach 2:
The seal plug is designed to automatically perform the sealing function without requiring additional user action or external mechanisms. After the hollow needle is removed, the seal plug self-actuates by moving under spring force, gravity, or elastic deformation to seal the lumen. This self-service mechanism eliminates the need for complex locking systems or user-operated seals, maintaining simplicity while ensuring reliability.
2Reliability
If a seal plug is added to prevent reuse, then the reliability improves by preventing contaminated liquid payload administration, but the device complexity increases due to additional components
Solution Approach 1:
The seal plug is integrated directly into the filter needle cap body as a unified component rather than being a separate attachable part. The seal plug may be molded as part of the cap body or firmly attached within it, combining the sealing function with the cap structure. This merging reduces the number of discrete components and simplifies assembly while maintaining the reliability benefit of automatic sealing upon needle removal.
Solution Approach 2:
The seal plug serves multiple functions: it seals the lumen to prevent reuse, maintains sterility by blocking the pathway, and may also help position or retain the filter element within the cap body. This multi-functionality reduces the need for additional specialized components, as the seal plug performs both sealing and sterility maintenance roles that would otherwise require separate elements.
3Manufacturing precision
If the seal plug is held in place during needle insertion, then the manufacturing precision is high for proper seal positioning, but the ease of operation decreases due to additional steps required to hold the seal plug
Solution Approach 1:
The holding mechanism for the seal plug is designed to be self-actuating based on the presence or absence of the hollow needle. During assembly, the needle itself may physically block or engage with a feature that holds the seal plug in place. When the needle is removed, the holding mechanism automatically releases, allowing the seal plug to move to its sealing position. This eliminates the need for separate user actions to hold or release the seal plug, maintaining ease of operation while ensuring precise positioning.
Solution Approach 2:
An intermediary feature such as a spring, detent, or friction fit is introduced between the seal plug and the cap body to provide automatic holding and release functionality. This intermediary mechanism translates the simple action of needle insertion or removal into the complex function of seal plug positioning and sealing. The intermediary handles the complexity of precise positioning and automatic actuation, keeping the user interface simple while achieving high manufacturing precision.
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
Prevents accidental reuse of the filter needle assembly by making it impossible to draw a second quantity of liquid payload, thereby ensuring patient safety and maintaining the integrity of the filtration process.
Implementation Method 1
a seal plug to surround a distal portion of the hollow needle after the distal tip of the hollow needle has been driven through the seal plug to form a seal between the seal plug and the distal portion of the hollow needle
Data Source
AI summary
A filtering needle assembly for use in administering a liquid payload, including: a needle and connector portion; a filtering needle body cap; a seal plug, and a filter: The seal plug initially lacking a needle channel so that a distal end of a hollow needle must be forced through the distal end of the seal plug while the seal plug is retained by a holding tool with a hollow midline of adequate depth to receive the protruding end of the hollow needle. An attempt to reuse the filtering needle assembly with a second insertion of a hollow needle into the filtering needle assembly will not work as the distal end of the hollow needle will push the seal plug distally rather than traverse the seal plug.