Rogowski Coil Flexible PCB Voltage Current Sensing
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Solution Overview
Problem
Existing electrosurgical generators using high permeability materials for current and voltage sensing face limitations such as non-linear output, temperature fluctuations, and poor tolerances, leading to inaccurate signal readings.
Innovation Solution
A Rogowski coil configured on a flexible printed circuit board with an outer coil and inner conductor, coupled with a conditioning circuit to provide a differentiated signal corresponding to the current passing through an active lead, which is then integrated to output a processed current signal, improving common mode rejection and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high permeability materials (e.g., ferrite) are used in transformers for voltage and current sensing, then the generator can be isolated from the patient, but the output becomes non-linear, fluctuates with temperature, and tolerances are not well-controlled, leading to inaccurate sensed signals
Solution Approach 1:
The patent removes the high permeability material (ferrite core) from the transformer structure, transitioning to an air-core or low-permeability core design. This extraction eliminates the temperature-dependent magnetic properties and non-linearity associated with ferrite materials, thereby improving signal accuracy while maintaining patient isolation through the transformer's inherent galvanic separation
Solution Approach 2:
The patent changes the magnetic permeability parameter of the core material from high (ferrite) to low (air or non-magnetic material). This parameter change stabilizes the transformer's magnetic characteristics across temperature variations, eliminates saturation effects, and provides well-controlled tolerances for accurate voltage and current sensing
2Reliability
If high permeability materials are used in transformers, then patient isolation is achieved, but the sensed signals become less accurate due to non-linear output, temperature fluctuations, and poor tolerances
Solution Approach 1:
The patent extracts the problematic high permeability material from the transformer, eliminating the source of manufacturing tolerance issues. The air-core or low-permeability core design provides consistent, predictable magnetic characteristics that are not subject to the variability and tolerance control problems associated with ferrite material manufacturing
Solution Approach 2:
By changing the core permeability parameter to a stable, well-defined value (air or non-magnetic material), the patent achieves superior manufacturing precision. The magnetic properties become independent of material batch variations and manufacturing tolerances, providing consistent transformer performance
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 solution enhances the accuracy of RF current and voltage measurements, overcoming the limitations of conventional sensors by providing stable and precise readings, thus improving the reliability of electrosurgical procedures.
Implementation Method 1
a Rogowski coil disposed on a flexible printed circuit board with at least one active lead passing through the Rogowski coil, the Rogowski coil configured to output a differentiated signal corresponding to a current passing through at least one active lead
Implementation Method 2
a conditioning circuit coupled to the Rogowski coil, the conditioning circuit configured to integrate the differentiated signal to output a processed current signal indicative of the current
Data Source
AI summary
A current sensor includes a Rogowski coil disposed on a flexible printed circuit board with at least one active lead passing through the Rogowski coil.