Atmospheric-Pressure Plasma Ignition Inside Narrow Tubes
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Solution Overview
Problem
Existing methods for igniting electric discharge plasma within narrow diameter tubes, such as flexible polymer tubes and rigid catheters, are inefficient, time-consuming, and costly due to the need for evacuated discharge chambers, making large-scale manufacturing of medical devices challenging.
Innovation Solution
A system and method for igniting plasma within the interior of narrow diameter tubes using ring-shaped anode and cathode electrodes at atmospheric pressure, without a dielectric barrier, and applying a voltage source to generate a strong electric field, allowing plasma etching of the interior surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing plasma ignition methods are used within narrow diameter tubes, then plasma can be ignited within sealed discharge chambers, but the system complexity and manufacturing time dramatically increase due to evacuation requirements
Solution Approach 1:
The patent changes the pressure parameter from vacuum to atmospheric pressure, eliminating the need for evacuation systems. This is achieved by using a dielectric barrier discharge configuration where the dielectric tube itself serves as the barrier, allowing plasma to be sustained at atmospheric pressure without complex vacuum equipment
Solution Approach 2:
The patent extracts and eliminates the vacuum evacuation chamber from the system by using atmospheric pressure operation. The dielectric tube is positioned between electrodes in a simple atmospheric pressure environment, removing the entire vacuum system complexity while maintaining reliable plasma ignition
2Manufacturing precision
If plasma etching is applied to interior surfaces of narrow diameter tubes, then surface hydrophilicity is enhanced, but the geometry of long thin tubes makes such interior surfaces difficult to access with electric discharge plasma
Solution Approach 1:
The patent uses a nested configuration where the dielectric tube is positioned between two electrodes (inner and outer), with the tube itself serving as the dielectric barrier. This nested arrangement allows the plasma to be generated within the tube's interior volume, enabling access to the interior surface of narrow diameter tubes that would otherwise be inaccessible
Solution Approach 2:
The patent transitions from attempting to access the tube interior through its length to generating plasma radially within the tube cross-section. By positioning electrodes on opposite sides of the tube and using the tube wall as the dielectric barrier, plasma is generated throughout the interior volume simultaneously, making the long thin geometry manageable
3Productivity
If atmospheric pressure plasma is used instead of vacuum plasma, then manufacturing complexity and time are reduced, but plasma ignition and maintenance becomes more challenging
Solution Approach 1:
The patent introduces a dielectric barrier (the tube wall itself) as an intermediary between the electrodes and the plasma. This dielectric barrier allows plasma to be sustained at atmospheric pressure by controlling the discharge through the dielectric material, making atmospheric pressure operation reliable while maintaining high productivity
Solution Approach 2:
The patent uses the tube wall itself as the dielectric barrier, making the tube serve dual purposes: as the object to be treated and as the plasma confinement structure. This self-service approach simplifies the system further while enabling reliable atmospheric pressure plasma operation
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 scalable and cost-effective plasma-etching of narrow diameter tubes, creating microscopic protrusions that enhance hydrophilicity and other surface properties, such as increased wettability and microbial resistance.
Implementation Method 1
applying a voltage source to generate a strong electric field
Implementation Method 2
ignite a plasma within the gas in the interior of the tube
Implementation Method 3
plasma-etch the interior surface of such tubes, thereby imparting the interior surface with protrusions that increase such interior surface's hydrophilicity
Data Source
AI summary
A system is provided for generating plasma within narrow diameter tubes, e.g., tubes with an inner diameter of less than 1 millimeter. The system may comprise the tube, a nozzle connected to at least one end of the tube configured to supply a gas into the interior of the tube at atmospheric pressure, at least one ring-shaped anode electrode and configured to surround an outer surface of the tube, at least one ring-shaped cathode electrode spaced apart from the anode electrode along the longitudinal axis and configured to surround the outer surface of the tube, and a voltage source connected to the at least one anode electrode. When activated, the system is configured to generate an electric field between the electrodes which ignites a plasma within the gas in the interior of the tube.