Electrosurgical Instrument with PTC Electrode for Tissue Welding
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Solution Overview
Problem
Current electrosurgical instruments face challenges in creating high-strength tissue welds, particularly for large diameter blood vessels, as existing bi-polar radiofrequency instruments struggle to achieve immediate post-treatment strength and durability.
Innovation Solution
The development of a surgical instrument with a dual-electrode end effector system, where one electrode comprises a porous material with an evaporable material and the other has a positive temperature coefficient (PTC) material that changes resistance based on temperature, allowing controlled energy delivery and tissue welding with enhanced mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional bi-polar radiofrequency instruments are used to seal large diameter blood vessels, then tissue welding is achieved, but the weld strength is insufficient immediately post-treatment
Solution Approach 1:
The electrode material undergoes a parameter change from conductive to non-conductive state through temperature-dependent resistance change. The PTC material's electrical resistance increases dramatically at the switching temperature, automatically controlling energy delivery and creating optimal conditions for strong tissue welding while preventing overheating and ensuring immediate post-treatment durability
Solution Approach 2:
The electrode is constructed as a composite material system combining PTC material with evaporable material. This composite structure enables both controlled energy delivery through resistance changes and enhanced tissue adhesion through material evaporation and bonding, resulting in superior weld strength and immediate post-treatment reliability
2Strength
If high energy is delivered to achieve strong welds, then weld strength improves, but risk of tissue damage and uncontrolled heating increases
Solution Approach 1:
The PTC material provides inherent feedback control through its temperature-dependent resistance characteristics. As the electrode temperature increases during tissue welding, the resistance automatically increases at the switching temperature, reducing current flow and preventing uncontrolled heating. This self-regulating mechanism ensures safe energy delivery while maintaining weld strength
Solution Approach 2:
The electrode's electrical resistance parameter changes dynamically with temperature. This parameter change from low resistance to high resistance at the switching temperature creates automatic feedback control, allowing sufficient energy delivery for strong welds while preventing excessive heating and tissue damage
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 instrument achieves a high-strength tissue weld by modulating electrical resistance and energy delivery, ensuring immediate post-treatment strength and durability, particularly for large diameter blood vessels, through the use of temperature-sensitive materials.
Implementation Method 1
the second electrode comprises a porous material and an evaporable material stored within the porous material
Implementation Method 2
the second material is configured to withdraw from the first material when the temperature of the second material at least one of meets or exceeds the switching temperature
Implementation Method 3
the other has a positive temperature coefficient (PTC) material that changes resistance based on temperature
Implementation Method 4
the delivery of Rf energy to the captured tissue elevates the temperature of the tissue and, as a result, the energy can at least partially denature proteins within the tissue
Data Source
AI summary
An electrosurgical surgical instrument can comprise a handle and an end effector, wherein the end effector can comprise first and second jaws which can be opened and closed in order to capture tissue therebetween. In various embodiments, the first and second jaws can comprise one or more electrodes configured to apply a voltage across the tissue, wherein at least one of the electrodes can comprise a conductive material positioned within a non-conductive, or high-resistance, material. In use, current flowing through the conductive material can heat the conductive material and cause it to evaporate and leave behind the non-conductive material. In such circumstances, the current flowing through the electrode may cease or may be substantially reduced.