Membrane Plunger Pressure Switch for Stable Infusion Occlusion Detection
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Solution Overview
Problem
Existing fluid pressure switches in medical infusion pumps face challenges due to sterilization and aging effects on elastomeric membranes, which alter their elastomeric properties and fail to maintain precise pressure measurements, leading to issues with occlusion detection and medication delivery accuracy.
Innovation Solution
A pressure switch design featuring a deformable elastic membrane, a plunger, and a spring mechanism that shifts the reaction force from the membrane to the spring, allowing for adjustable trigger pressure without strict material and dimensional requirements, and includes conductive elements for electrical circuit closure upon threshold pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a membrane-based pressure switch is used to detect pressure changes in an infusion pump, then pressure sensing function is achieved, but sterilization and aging alter the elastomeric properties of the membrane causing measurement inaccuracy
Solution Approach 1:
The pressure sensing system is segmented into two functional parts: the membrane that contacts sterilized fluid and the plunger-spring mechanism that performs measurement. The membrane only needs to transmit pressure, while the spring provides the reactive force, separating the sterilization-exposed component from the measurement-critical component.
Solution Approach 2:
The system changes the physical state and properties of the reactive force mechanism from elastomeric (membrane) to metallic/mechanical (spring). The spring's material properties remain stable through sterilization and aging, unlike elastomeric membranes whose properties drift over time.
2Measurement precision
If strict material characteristics and dimensional tolerances are imposed on the membrane to improve measurement precision, then measurement precision improves, but manufacturing complexity and cost increase
Solution Approach 1:
The plunger acts as an intermediary between the membrane and the measurement mechanism. It transfers pressure from the membrane while the spring provides the reactive force, isolating the measurement function from the membrane's dimensional variations.
Solution Approach 2:
The system changes the source of the reactive force from the membrane's elastomeric properties to a mechanical spring's elastic properties. This shifts the measurement precision dependency from membrane thickness and material characteristics to spring characteristics, which are more stable and easier to manufacture with consistent properties.
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
This design enhances occlusion detection and medication delivery accuracy by minimizing membrane-related issues, providing reliable and adjustable pressure sensing without the need for precise material characteristics and tolerances, and allowing for resettable operation.
Implementation Method 1
an elastic membrane sealing the opening in a baseplate, wherein the elastic membrane is deformable by pressure from fluid within the fluid path
Implementation Method 2
a spring, disposed between the upper plate and the plunger and exerting a pressure against the plunger
Data Source
AI summary
A pressure switch is provided and includes an elastic membrane disposed such that pressure from fluid within a fluid path deforms the elastic membrane toward a plunger, thereby moving the plunger. The plunger is disposed between the membrane and an upper plate and is moveable along an axis extending between the membrane and the upper plate. A threshold pressure on the membrane from the fluid within the fluid path deforms the membrane, thereby moving the plunger toward the upper plate.