IONM Switch Matrix With Digital DC Offset Correction
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Solution Overview
Problem
Conventional intraoperative neurophysiological monitoring (IONM) systems face challenges in accurately configuring channels due to potential disturbances in control lines and electrode offset voltage potentials, leading to improper signal monitoring and prolonged recovery times from electrical disturbances.
Innovation Solution
An electronic circuit with a microcontroller, FPGA, and logic module is used to automatically detect and correct channel configuration errors and offset voltage potentials, employing a dual-output register system and digital control loop for real-time reconfiguration and DC offset correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AC coupling is used to eliminate offset voltage potential, then offset voltage rejection is improved, but amplifier settling time and recovery time are extended
Solution Approach 1:
The patent changes the coupling parameter from AC to DC, and introduces a digital DC offset correction mechanism that dynamically adjusts the offset voltage parameter to achieve rejection without the time penalty of AC coupling
Solution Approach 2:
The patent replaces the analog AC coupling mechanism with a digital DC offset correction system that uses digital signal processing to eliminate offset voltage, avoiding the temporal characteristics of analog coupling circuits
2Adaptability or versatility
If latching multiplexers are used for channel configuration, then channel routing flexibility is improved, but control line disturbance detection capability deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the microcontroller continuously monitors control line states and automatically detects disturbances, then rewrites the configuration data to correct errors, creating a closed-loop system that maintains reliability
Solution Approach 2:
The system performs self-diagnosis and self-correction by automatically detecting control line disturbances and rewriting configuration data without external intervention, maintaining both flexibility and reliability
3Ease of operation
If microcontroller directly controls multiplexer control lines, then channel configuration capability is improved, but electrical noise interference increases
Solution Approach 1:
The patent introduces an intermediary mechanism where the microcontroller writes configuration data to a buffer register, and the actual control lines are updated through a controlled interface that isolates the microcontroller from direct electrical connection to the multiplexer control lines
Solution Approach 2:
The patent extracts the microcontroller from direct control of the multiplexer control lines, separating the logical configuration function from the physical electrical connection to eliminate noise generation
4Adaptability or versatility
If more amplifier channels are needed, then monitoring coverage is improved, but system complexity increases
Solution Approach 1:
The patent makes a single amplifier capable of performing multiple channel functions through programmable switch matrices that can dynamically reconfigure which electrodes are connected to which amplifier inputs, allowing one amplifier to replace multiple fixed amplifiers
Solution Approach 2:
The patent introduces dynamic reconfiguration capability where the switch matrices can change connections in real-time based on monitoring needs, allowing the system to adapt channel assignments without adding physical hardware
Data Source
AI summary
A multi-modality intraoperative neurophysiological monitoring (IONM) system includes at least one amplifier integrated with a programmable switch matrix module configured to have up to 32 patient connected electrode inputs that are multiplexed to up to 24 amplifier channels. In some scenarios, a capacitor is positioned in series with electrode inputs of the at least one amplifier, such that the capacitor eliminates DC offset voltages from the electrode inputs while allowing neural AC signals to pass through to the at least one amplifier. In some scenarios, the switch matrix module includes a digital control loop configured to automatically eliminate offset voltage potential in patient connected electrodes. The switch matrix module further includes a field programmable gate array (FPGA) configured to automatically reset a plurality of control lines of one or more multiplexers of the switch matrix module.