Microhollow Cathode Plasma Jet for Low-Temperature Tissue Treatment
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Solution Overview
Problem
Existing plasma devices struggle to generate a stable, low-temperature non-thermal plasma jet at atmospheric pressure suitable for use on heat-sensitive materials and living tissues, often requiring high power consumption, noble gases, and being prone to arcing and instability.
Innovation Solution
A microhollow cathode plasma jet discharge device using a microhollow structure with a planar anode and cathode separated by a dielectric, operated with direct current, which generates a stable glow discharge at atmospheric pressure, allowing for the creation of a low-temperature plasma jet using air or nitrogen, and is scalable for various applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If radio frequency power is used to generate plasma discharge at atmospheric pressure, then plasma generation is achieved, but the plasma temperature becomes too high for heat-sensitive materials and power consumption increases
Solution Approach 1:
The plasma generation process is segmented into two independent stages: (1) RF discharge in a first gas to generate plasma, and (2) plasma transfer to a second gas that contacts the target. This segmentation allows temperature control in the plasma-generating region while maintaining low temperature in the treatment region.
Solution Approach 2:
A first gas (such as helium or argon) serves as an intermediary medium to generate plasma that is then transferred through a second gas (such as air or nitrogen) to the target. The intermediary gas decouples the plasma generation temperature from the treatment temperature, enabling low-temperature plasma application.
2Reliability
If atmospheric pressure plasma is generated using conventional methods, then plasma discharge is achieved, but the system becomes unstable and prone to arcing
Solution Approach 1:
The first gas acts as an intermediary that provides stable plasma generation conditions, while the second gas provides a stable, non-arcing environment for plasma transfer and treatment. This dual-gas intermediary system eliminates the instability and arcing problems associated with direct atmospheric pressure plasma generation.
Solution Approach 2:
The system changes the gas composition parameter between the plasma generation region (first gas) and the treatment region (second gas). By selecting gases with appropriate properties for each region, the system achieves stable discharge in the first gas while preventing arcing in the second gas environment.
3Temperature
If linear dimension of the device is reduced to reduce residence time and prevent heating, then plasma generation at atmospheric pressure is improved, but scalability and power consumption are affected
Solution Approach 1:
The device is segmented into a compact plasma generation chamber (first chamber) and a separate treatment chamber (second chamber) connected by a transfer path. This spatial segmentation allows the plasma generation region to be small for temperature control, while the overall system can be scaled by adjusting chamber volumes and transfer path characteristics.
Solution Approach 2:
The plasma transfer from the first chamber to the second chamber introduces a spatial dimension for temperature control. The plasma cools during transfer through the second gas, allowing the system to achieve temperature control not just through size reduction but through spatial separation and controlled transfer dynamics.
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 device produces a highly efficient, controllable low-temperature plasma jet suitable for surface treatment, sterilization, and decontamination, with reduced power consumption and the ability to operate in ambient air, effectively generating reactive species like ozone and atomic oxygen for interaction with tissues and contaminants.
Implementation Method 1
a non-thermal plasma glow discharge at or near atmospheric pressure
Implementation Method 2
application of a direct current so as to produce microhollow discharges
Implementation Method 3
reducing residence time of the gas in the electric field
Implementation Method 4
plasma is an electrically neutral, ionized state of gas, which is composed of ions, free electrons, and neutral species
Implementation Method 5
generation of reactive species such as hydroxyl groups and atomic oxygen
Data Source
AI summary
A microhollow cathode discharge assembly capable of generating a low temperature, atmospheric pressure plasma micro jet is disclosed. The microhollow assembly has at two electrodes: an anode and a cathode separated by a dielectric. A microhollow gas passage is disposed through the three layers, preferably in a taper such that the area at the anode is larger than the area at the cathode. When a potential is placed across the electrodes and a gas is directed through the gas passage into the anode and out the cathode, along the tapered direction, then a low temperature micro plasma jet can be created at atmospheric pressure. Selection of gas microhollow geometry and operational characteristics enable the application of the assembly to low temperature treatments, including the treatment of living tissue.