Biosignal Acquisition Apparatus for HF Interference Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing technologies struggle to effectively filter out high-frequency (HF) interferences in clinical environments, particularly during surgeries involving electro-surgical units (ESUs), which can corrupt electro-physiological signals such as EEG and EMG, rendering them unreliable for real-time monitoring.
Innovation Solution
The proposed solution involves a dual-circuitry approach with a front-end active filter and an isolation barrier to block HF interferences, along with a cross-barrier voltage measurement circuitry to quantify interference levels and dynamically adjust signal processing to ensure data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional passive filters and simple isolation interfaces are used, then device complexity is reduced, but HF interference blocking capability deteriorates
Solution Approach 1:
The patent divides the interference blocking function into multiple independent stages: front-end active filters, low-frequency EMI shields, and isolation barrier interfaces. Each stage handles a specific frequency range or aspect of interference, allowing the system to achieve comprehensive HF blocking without requiring a single overly complex circuit design.
Solution Approach 2:
The front-end active filters are positioned before the instrumentation amplifiers to proactively attenuate HF interferences before they can saturate the amplifier. This preliminary filtering action prevents the interference from reaching subsequent circuit stages, reducing the burden on later processing stages.
2Object-affected harmful factors
If aggressive HF filtering is applied, then HF interference is reduced, but measurement precision of bio-signals deteriorates
Solution Approach 1:
The patent applies different filtering characteristics to different parts of the signal path. The front-end active filters provide strong HF attenuation, while the isolation barrier interfaces maintain high input impedance to preserve signal integrity. This localized approach ensures HF blocking where needed without compromising bio-signal measurement precision.
Solution Approach 2:
The cross-barrier voltage measurement circuitry provides feedback about the interference level to the processing means. This feedback enables dynamic adjustment of signal processing parameters, allowing the system to adapt to varying interference conditions and maintain measurement precision despite aggressive filtering.
3Reliability
If isolation barrier interface is added, then patient safety is improved, but device complexity increases
Solution Approach 1:
The isolation barrier interface acts as an intermediary between the patient-side electronics and the computer-side electronics. It provides galvanic isolation to protect the patient from electrical hazards while still allowing signal transmission through the cross-barrier voltage measurement capability, thus achieving safety without complete signal loss.
4Measurement precision
If cross-barrier voltage measurement circuitry is added, then interference detection accuracy is improved, but device complexity increases
Solution Approach 1:
The cross-barrier voltage measurement circuitry serves multiple functions: it measures interference levels for feedback control, provides a diagnostic indicator of filter performance, and enables dynamic adjustment of signal processing parameters. This multi-functionality justifies the added circuit complexity by delivering multiple benefits from a single measurement capability.
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 approach significantly reduces HF interference, allowing for accurate and reliable acquisition of electro-physiological signals even in harsh HF environments, thereby ensuring the integrity of patient monitoring data during surgeries.
Implementation Method 1
a front-end active filter, a low frequency electromagnetic interference ('EMI') shield, and an isolation barrier interface which isolates the patient from earth ground
Implementation Method 2
a low frequency electromagnetic interference ('EMI') shield
Implementation Method 3
an isolation barrier interface which isolates the patient from earth ground
Implementation Method 4
The second circuitry is used to measure the difference in potential between the two isolated sides of the isolation barrier. This so-called 'cross-barrier' voltage is directly representative of the interference level
Data Source
AI summary
The present invention herein is a method and apparatus that significantly limits the effect of high frequency (“HF”) interferences on acquired electro-physiological signals, such as the EEG and EMG. Preferably, this method comprises of two separate electronic circuitries and steps or electronics for processing the signals. One circuit is used to block the transmission of HF interferences to the instrumentation amplifiers. It is comprised of a front-end active filter, a low frequency electromagnetic interference (“EMI”) shield, and an isolation barrier interface which isolates the patient from earth ground. The second circuit is used to measure the difference in potential between the two isolated sides of the isolation barrier. This so-called “cross-barrier” voltage is directly representative of the interference level that the instrumentation amplifier is subjected to. This circuit is used to confirm that the acquired signals are not corrupted by the interference.