Adaptive Right Leg Drive for MRI Bio-Potential Noise Rejection
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Solution Overview
Problem
Conventional systems for taking bio-potential measurements, such as ECG, EEG, and EMG, face challenges in rejecting noise and interference, especially in harsh environments like MRI rooms, where existing common mode rejection methods fail.
Innovation Solution
The implementation of an adaptive right leg drive (ARLD) system that includes bio-potential signal sensors, a driving electrode, and an ARLD circuit with a feedback loop and controller. This system adaptively changes its operating mode based on environmental conditions, such as the presence of strong magnetic fields, to improve signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional common mode rejection methods are used, then noise rejection is achieved in normal environments, but the methods fail in harsh environments like MRI rooms
Solution Approach 1:
The system dynamically adapts its operating mode based on environmental conditions. The controller monitors environmental parameters and switches between first operating mode (for normal environments with conventional common mode rejection) and second operating mode (for harsh environments like MRI rooms with specialized noise cancellation), enabling the system to maintain reliability across varying conditions
Solution Approach 2:
The system changes its operational parameters based on the detected environment. In the first operating mode, conventional common mode rejection parameters are used, while in the second operating mode, parameters are adjusted to account for harsh environment characteristics, allowing the system to effectively reject noise in both normal and harsh conditions
2Measurement precision
If bio-potential signals are amplified to make them acquirable, then signal strength is improved, but noise and interference signals are also amplified
Solution Approach 1:
The system employs feedback mechanisms where the controller continuously monitors the bio-potential signals and environmental conditions. Based on this feedback, the system adjusts amplification levels and activates appropriate noise rejection strategies, ensuring that signal strength is improved while minimizing the amplification of noise and interference
Solution Approach 2:
The system extracts and separates the desirable bio-potential signal from noise and interference signals through selective amplification and filtering. By identifying and isolating the signal of interest from harmful components, the system achieves measurement precision without proportionally amplifying noise
3Adaptability or versatility
If adaptive mode switching is implemented, then environmental adaptability is improved, but device complexity increases
Solution Approach 1:
The controller is designed to perform multiple functions: monitoring environmental parameters, determining operating modes, switching between modes, and coordinating noise rejection strategies. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in device complexity while achieving improved environmental adaptability
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 ARLD system effectively reduces noise interference and improves the common mode rejection ratio (CMRR) of bio-potential signals, even in challenging environments like MRI rooms, thereby enhancing the reliability and accuracy of bio-potential measurements.
Implementation Method 1
The ARLD circuit can include a feedback circuit for receiving the bio-potential signals from the patient via the one or more bio-potential signal sensors and outputting a feedback signal
Implementation Method 2
The driving electrode can receive the driving output signal from the ARLD circuit and can apply the driving output signal to the patient
Data Source
AI summary
The present disclosure describes various systems and methods of adaptively taking bio-potential measurements of within a changing environments. Specifically, the systems and methods are directed to adaptive control of a bio-potential measurement device thereby enabling the use of the bio-potential measurement device within environments having different noise sources, such as environments with and without a device generating strong magnetic fields. Through adaptive measures, the systems and methods of the present disclosure improve the usage of a right leg drive by adaptively changing the nature of the drive itself according to its present environment (e.g., MR vs. non-MR environment). In addition to improvements in common mode rejection (CMR), the systems and methods of the present disclosure can reduce the required analog front-end dynamic range.