Electrosurgical Cable with Nested Conductors for Zero EM Field
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Solution Overview
Problem
Conventional electrosurgical cables produce significant electromagnetic fields and pose a risk of electric shock due to high local electric fields, which can be hazardous during procedures.
Innovation Solution
The electrosurgical cable design features two conductors, an inner high voltage conductor and an outer conductor connected to a patient pad, with the inner conductor's insulation ensuring that the voltage applied to the gas gap is below the breakdown threshold, preventing plasma discharge and shielding the cable from EM fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional one-electrode electrosurgical cable is used, then high voltage can be delivered to the handpiece, but strong electromagnetic fields are generated around the cable
Solution Approach 1:
The harmful electromagnetic field generation is eliminated by extracting the antenna effect from the cable design. This is achieved by using a two-conductor configuration where the voltage drop across the inner insulator prevents plasma discharge inside the cable, thereby removing the cable's ability to radiate electromagnetic fields while preserving its function of delivering high voltage to the handpiece.
Solution Approach 2:
The cable employs a nested structure with an inner conductor surrounded by an inner insulator, which is itself surrounded by an outer conductor. This nested configuration creates a shielded environment where the inner high-voltage conductor is isolated from the outer conductor by the inner insulator, preventing electromagnetic field generation while allowing high voltage delivery to the handpiece.
2Power
If high voltage is applied to the electrode, then electrosurgical operation is enabled, but risk of electric shock increases
Solution Approach 1:
The nested structure provides multiple layers of protection: the inner insulator isolates the high-voltage inner conductor from the outer conductor, and the outer conductor provides additional shielding. This multi-layer nested configuration ensures that even if one insulation layer is compromised, the other layers continue to provide protection, thereby enabling electrosurgical operation while significantly reducing electric shock risk.
Solution Approach 2:
The design incorporates redundant insulation layers and a shielded structure that provide beforehand protection against insulation failure. The outer conductor and outer insulator act as a protective barrier that cushions against potential electric shock hazards before they can affect the patient or operator, allowing high voltage operation with enhanced safety.
3Object-generated harmful factors
If a two-conductor configuration is used with inner insulator, then electromagnetic field is shielded and electric shock risk is reduced, but device complexity increases
Solution Approach 1:
The nested configuration of conductors and insulators, while providing superior shielding and safety, follows a systematic structure where each layer serves a specific function. The inner conductor carries high voltage, the inner insulator provides primary isolation, the outer conductor provides shielding, and the outer insulator provides additional protection. This organized nested structure achieves enhanced safety and EM field shielding with a methodical design that manages complexity through functional segmentation.
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 eliminates EM-field production and significantly reduces the risk of electric shock for human subjects by ensuring that any compromise in insulation results in a safe, shielded electrode or short-circuit condition.
Implementation Method 1
High voltage applied to the central electrode (U 0 ) is chosen above the breakdown threshold (U BD ) in order to initiate discharge on the electrosurgical handpiece (U 0 > U BD ). However, inside the cable a significant fraction of the applied voltage drops on the inner insulator, so that remaining voltage applied to the gas gap (U gas ) is below the breakdown threshold
Implementation Method 2
The present invention utilizes two conductors, namely an inner high voltage conductor and an outer conductor (connected to patient pad). The critical feature of present invention is that inner conductor electrical insulation that provides the following critical function.
Data Source
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AI summary
An electrosurgical cable that produces no electromagnetic (EM) field around its vicinity (zero-EM pollution). The cable is comprised of inner insulator with embedded conductor placed inside the outer insulator tube with embedded second conductor. Sizes and materials of conductors and insulators are chosen so that voltage applied to inner conductor is higher than the breakdown voltage while voltage applied to gas gap inside the electrosurgical cable is below than the breakdown voltage. Therefore, the cable is producing discharge at the surgical handpiece, but breakdown inside the cable is prohibited.