Multi-Point Artifact Cancellation in Neural Stimulation Systems
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Solution Overview
Problem
Current biomedical systems for responsive neurostimulation and brain-machine interfaces face challenges in simultaneously recording and stimulating neural signals due to artifacts introduced by stimulation, which degrade signal quality and require high power consumption and large voltages, limiting the dynamic range and effective number of bits for signal quantization.
Innovation Solution
A system employing two-point artifact suppression techniques that cancel stimulation artifacts at multiple stages of signal amplification, boosting common-mode and differential-mode suppression to 68.5 dB and 58.1 dB respectively, allowing for concurrent stimulation and recording while maintaining signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oversampling ADCs are used to increase dynamic range and accommodate large artifacts, then the linear dynamic range is improved, but the energy consumption for data transmission and digital processing increases drastically
Solution Approach 1:
The patent applies preliminary action by estimating and canceling stimulation artifacts at the front end before the signal reaches the ADC. This preprocessing step removes the harmful artifact component beforehand, allowing the use of lower-resolution ADCs (10-12 bits) instead of high-resolution oversampling ADCs, thereby significantly reducing the energy consumption for data transmission and digital processing while maintaining adequate dynamic range for neural signal recording
2Adaptability or versatility
If adaptive digital filters are used to estimate and cancel artifact at the front end, then the dynamic response requirements of the ADC are relaxed, but the artifact suppression is limited
Solution Approach 1:
The patent applies segmentation by implementing a two-stage artifact cancellation process: first canceling the stimulation artifact at the input to the first amplifier, then canceling the residual artifact at the input to the second amplifier. This segmented approach divides the artifact suppression task into multiple stages, achieving superior overall artifact suppression (greater than 100 dB) compared to single-stage methods, while maintaining relaxed ADC dynamic response requirements
Solution Approach 2:
The patent employs feedback mechanisms in both artifact cancellation stages, where the estimated artifact signal is fed back and subtracted from the recorded signal. The system uses adaptive filtering with feedback loops that continuously adjust the cancellation parameters based on the detected artifact characteristics, enabling precise artifact removal while maintaining system adaptability to varying stimulation conditions
3Reliability
If stimulation signals are delivered to prevent seizures, then the therapeutic effect is improved, but artifacts are introduced that degrade signal quality
Solution Approach 1:
The patent converts the harmful stimulation artifact into a beneficial component by using the artifact itself as a reference signal for cancellation. The system captures the artifact generated during stimulation, processes it through adaptive filters to create an accurate artifact model, and then subtracts this modeled artifact from the recorded neural signals. This approach transforms the previously harmful artifact into a useful reference that enables precise artifact removal, allowing simultaneous stimulation and recording with high signal quality
Data Source
AI summary
A system and method for reducing or eliminating undesired effects of an artifact on a received signal is disclosed. The signal is generated from stimulating a sample. A receiver includes estimations of artifacts on the signal that are subtracted at different stages of the receiver. The estimations of the artifact may be performed via a successive approximation register scheme.