Collapsible Syringe Plunger with Stress-Induced Decoupling
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Solution Overview
Problem
Syringes lack a mechanism to control fluid dispensing based on the force applied to the plunger, potentially leading to unsafe conditions when the force required exceeds a critical threshold, such as during the curing of polymer materials in ophthalmologic procedures.
Innovation Solution
A syringe design featuring a plunger member with a contact portion that allows the top and bottom portions to move independently when a stress exceeding a critical stress is induced, preventing further fluid dispensing by mechanically failing and preventing force transfer from the top to the bottom portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional syringe plunger is used, then fluid can be dispensed continuously regardless of force applied, but the syringe cannot terminate dispensing when excessive force is applied, creating unsafe conditions
Solution Approach 1:
The plunger member is segmented into a top portion, a contact portion, and a bottom portion. The contact portion is designed as a separate element that can fail independently, allowing the top portion to decouple from the bottom portion when excessive force is applied. This segmentation enables the syringe to automatically terminate fluid dispensing while maintaining ease of operation during normal use.
2Reliability
If the plunger is designed to allow independent movement of top and bottom portions, then force transfer can be prevented when stress exceeds critical stress, but the device complexity increases
Solution Approach 1:
The contact portion serves as an intermediary element between the top portion and bottom portion of the plunger. It is specifically designed to be the weakest link that fails under excessive stress, acting as a mechanical fuse. This intermediary structure enables automatic force transfer prevention without requiring complex sensors, actuators, or control systems, thus maintaining relatively simple device architecture while achieving reliable force control.
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 fluid dispensing when excessive force is applied, ensuring safety by preventing the transfer of force after the contact portion fails, thus avoiding unsafe conditions during procedures like ophthalmologic surgeries where materials may cure and become unsafe to dispense.
Implementation Method 1
The contact portion permits the top portion to move independent of the bottom portion in response to a stress in the contact portion exceeding a critical stress. The stress in the contact portion is based on the first force applied to the first end of the top portion and a second force opposite the first force, the second force applied to the second end of the bottom portion by a fluid in the second inner volume portion of the inner chamber.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
In a general aspect, a syringe terminates the dispensing of a fluid based on a force applied to a plunger member of the syringe. In some aspects, a plunger member of a syringe includes a top portion, a bottom portion, and a contact portion. The top and bottom portions are in contact with the contact portion, and the bottom portion has a length greater than or equal to a length of the top portion. The contact portion permits the top portion to move independent of the bottom portion in response to a stress in the contact portion exceeding a critical stress. The stress in the contact portion is based on a first force applied to the top portion and a second force opposite the first force applied to the bottom portion.