Microwave Plasma Nozzle Helical Flow Shielding
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Solution Overview
Problem
Existing plasma sterilization methods face challenges such as high operational costs, inefficiencies, thermal sensitivity, and damage to heat-sensitive materials due to high plasma temperatures, making them unsuitable for effective and economical sterilization of medical devices and equipment.
Innovation Solution
A microwave plasma generator system operating at atmospheric pressure, utilizing a nozzle with a gas flow tube and a rod-shaped conductor, which imparts a helical flow direction to the gas, and includes a grounded shield to reduce microwave power loss, generating a relatively cool plasma suitable for sterilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high voltage AC or Pulsed DC is used to induce arc within nozzle to generate plasma, then plasma generation is achieved, but power consumption increases and plasma temperature becomes too high
Solution Approach 1:
The patent replaces the mechanical/electrical arc discharge system with a microwave-based plasma generation system. The microwave generator (21) produces electromagnetic energy that couples with the gas flow to create plasma without requiring high voltage arcs, thereby reducing power consumption and controlling plasma temperature.
Solution Approach 2:
The patent changes the operating parameters by using microwave frequency (2.45 GHz) instead of high voltage AC or Pulsed DC. This parameter change enables plasma generation at lower power consumption and controlled temperatures suitable for heat-sensitive materials.
2Stability of the object's composition
If plasma is generated inside nozzle and guided by narrow slits, then plasma directionality is improved, but active radicals are lost inside the nozzle
Solution Approach 1:
The patent performs preliminary action by generating plasma after the gas exits the nozzle, rather than inside the nozzle. The microwave generator creates plasma in the region where the gas flow is already established, preventing radical losses that would occur during transport through narrow nozzle slits.
Solution Approach 2:
The patent introduces a dielectric material (40) as an intermediary between the microwave generator and the gas flow. This dielectric material couples the microwave energy to the gas, enabling plasma generation without direct contact between the microwave source and the gas, thereby preventing radical losses while maintaining plume stability.
3Reliability
If low pressure plasma is used for sterilization, then sterilization capability is achieved, but vacuum equipment and batch process units are required increasing complexity and cost
Solution Approach 1:
The patent changes the pressure parameter from low pressure (vacuum) to atmospheric pressure operation. The microwave plasma generator can effectively generate plasma at atmospheric pressure, eliminating the need for vacuum equipment and batch process units, thereby reducing device complexity and operational costs while maintaining sterilization effectiveness.
4Reliability
If high temperature plasma is used for sterilization, then sterilization capability is improved, but heat-sensitive materials are damaged
Solution Approach 1:
The patent changes the temperature parameter by using microwave frequency (2.45 GHz) instead of high voltage arcs, enabling plasma generation at controlled, lower temperatures. This parameter change allows effective sterilization while preventing thermal damage to heat-sensitive medical devices and materials.
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 system achieves efficient, low-cost, and rapid sterilization of heat-sensitive materials without the need for vacuum equipment, producing a cool plasma that effectively targets bacterial cell membranes with reactive neutrals and UV light.
Implementation Method 1
a microwave plasma generator which uses microwaves to heat and ionize a gas
Implementation Method 2
heat and ionize a gas, generating a plasma
Implementation Method 3
The vortex guide has at least one passage that is angled with respect to a longitudinal axis of the rod-shaped conductor for imparting a helical shaped flow direction around the rod-shaped conductor to a gas passing along the passage
Implementation Method 4
A grounded shield may be disposed on an exterior surface of the gas flow tube to reduce a microwave power loss through the gas flow tube
Data Source
AI summary
Systems and methods for generating microwave plasma are disclosed. The present invention provides a microwave plasma nozzle (26) that includes a gas flow tube (40), and a rod-shaped conductor (34) that is disposed in the gas flow tube (40) and has a tip (33) near the outlet of the gas flow tube (40). A portion (35) of the rod-shaped conductor (34) extends into a microwave cavity (24) to receive microwaves passing in the cavity (24). These received microwaves are focused at the tip (33) to heat the gas into plasma. The microwave plasma nozzle (26) also includes a vortex guide (36) between the rod-shaped conductor (34) and the gas flow tube (40) imparting a helical shaped flow direction to the gas flowing through the tube (40). The microwave plasma nozzle (26) further includes a shielding mechanism (108) for reducing a microwave power loss through the gas flow tube (40).