Physiological signal acquisition system and method with improved noise and common mode rejection performance and signal quality
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Publication Number
US-12028103-B1
Publication Date
2024-07-02
Expiration Date
Abstract
The present invention relates to the acquisition, processing, and monitoring of signals, and particularly to the acquisition, processing, and monitoring of electrophysiological signals. More particularly, the present invention relates to the acquisition, processing, and monitoring electroencephalography (EEG) signals representing cortical/brain activity. Further, the present invention relates to a method and apparatus for acquiring such signals in the presence of electrical interference and noise. More particularly, the present invention relates to systems and methods for filtering out and rejecting electrical interference and noise while maintaining or improving the quality of the underlying physiological signal and preventing perturbation or introduction of artifacts into the physiological signal.
Core Innovation
A system measures depth of anesthesia or sedation using at least two EEG electrodes each with a lead, an analog front-end circuitry for acquisition of an EEG physiological signal, a processor adapted for quantifying the filtered EEG physiological signal, and a monitor for displaying a quantified, filtered EEG signal. The acquisition circuitry includes at least two inputs for inputting the EEG physiological signal, at least two bootstrapped filters, and at least one instrumentation amplifier comprising at least two amplifiers.
Each bootstrapped filter includes a resistor, a first capacitor and a second capacitor, and a unity gain buffer. In each bootstrapped filter, the resistor and first capacitor form a low-pass filter, while the second capacitor is driven to have substantially the same upper and lower alternating current voltage as when the EEG physiological signal enters the input, by a common mode signal or a physiological signal potential.
Each bootstrapped filter is directly connected to a common node of the at least two amplifiers of the instrumentation amplifier, and the bootstrapped filter is external to the instrumentation amplifier. The bootstrapped filter is adapted to remove common mode signal from the EEG physiological signal prior to the signal entering the instrumentation amplifier, and the system is adapted to have a common mode rejection ratio of 95 or greater dB.
The described architecture is also used for measuring a physiological brain signal with deep brain electrodes, with at least two deep brain electrodes, analogous analog front-end circuitry, and an output for displaying the physiological brain signal. The system is adapted to allow additional channels to be added by adding an additional bootstrapped filter and using an existing channel as a reference while maintaining the common mode rejection ratio requirement.
Claims Coverage
The consolidated content includes two independent claims, each centered on an analog front-end architecture that uses external bootstrapped filters to remove common mode signal before instrumentation amplification, enabling a common mode rejection ratio of at least 95 dB.
Depth of anesthesia or sedation EEG system with external bootstrapped filters for common mode removal
A system for measuring depth of anesthesia or sedation comprising at least two EEG electrodes each with a lead, circuitry for acquisition of an EEG physiological signal with analog front-end circuitry, a processor adapted for quantifying the filtered EEG physiological signal, and a monitor for displaying a quantified, filtered EEG signal, wherein the acquisition circuitry includes at least two bootstrapped filters external to the instrumentation amplifier and adapted to remove common mode signal prior to the signal entering the instrumentation amplifier, and wherein the system is adapted to have a common mode rejection ratio of 95 or greater dB.
Deep brain electrode physiological brain signal system with channel-expandable external bootstrapped filters
A system for measuring a physiological brain signal with deep brain electrodes comprising at least two deep brain electrodes, circuitry for acquisition with analog front-end circuitry, and an output for displaying the physiological brain signal, wherein the analog front-end circuitry includes bootstrapped filters external to the instrumentation amplifier and adapted to remove common mode signal prior to the signal entering the instrumentation amplifier, wherein each bootstrapped filter is directly connected to a common node for each of the at least two amplifiers for each instrumentation amplifier, wherein the system is adapted to allow additional channels to be added by adding an additional bootstrapped filter and using an existing channel as a reference, and wherein the system is adapted to have a common mode rejection ratio of 95 or greater dB.
Both independent claims share the main inventive concept of using external bootstrapped low-pass filter networks, each having a unity gain buffer and capacitor drive based on common mode signal or physiological signal potential, connected to common nodes of an instrumentation amplifier to remove common mode signal before amplification, achieving a common mode rejection ratio of 95 or greater dB; the second claim further adds a deep brain electrode configuration with channel expansion.
Stated Advantages
Achieves a common mode rejection ratio of 95 or greater dB.
Removes common mode signal from the physiological/EEG signal prior to entering the instrumentation amplifier.
Supports adding additional channels by adding an additional bootstrapped filter and using an existing channel as a reference.
Documented Applications
Measuring depth of anesthesia or sedation using EEG physiological signals from at least two EEG electrodes.
Measuring a physiological brain signal using deep brain electrodes.
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