Simultaneous Physiological Sensing and Stimulation Saturation Detection
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Solution Overview
Problem
The application of electrical stimulation in medical devices for treating movement disorders and neurodegenerative impairments often obscures neurological bioelectrical signals, leading to unreliable sensing and monitoring due to amplifier saturation, resulting in missed information during stimulation.
Innovation Solution
A system and method that includes applying a test tone signal with distinct frequency content to monitor the reliability of sense signals, allowing for simultaneous stimulation and sensing while avoiding signal chain saturation by adjusting amplifier gain based on the magnitude of the test frequency, ensuring reliable signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical stimulation is applied to treat movement disorders, then therapeutic effect is improved, but neurological bioelectrical signals become obscured due to amplifier saturation
Solution Approach 1:
A test tone signal is introduced as an intermediary to monitor amplifier saturation. The test tone frequency serves as a marker that, when detected in the amplified neurological signals, indicates that the amplifier has saturated and the bioelectrical signal information is unreliable. This intermediary allows indirect detection of saturation without directly interfering with the therapeutic stimulation.
Solution Approach 2:
The system implements feedback by continuously monitoring the amplified signals for the presence of the test tone frequency. When the test tone is detected, the system generates an indication that the amplifier is saturated, providing real-time feedback about signal reliability. This feedback mechanism allows the system to identify when bioelectrical signal information has been lost due to saturation.
2Measurement precision
If amplifiers are used to amplify neurological bioelectrical signals, then signal magnitude is improved, but amplifier saturation occurs during electrical stimulation
Solution Approach 1:
The test tone signal acts as an intermediary indicator of amplifier saturation. By monitoring for the presence of this known frequency in the amplified output, the system can determine whether the amplifier has saturated, thereby assessing the reliability of the amplified neurological signals without directly measuring saturation itself.
Solution Approach 2:
The system uses frequency domain analysis to detect changes in the spectral content of the amplified signal. The appearance of the test tone frequency in the spectrum serves as a detectable change that indicates saturation, analogous to using color changes as indicators in other systems.
3Reliability
If sensing electrodes are blocked during stimulation to avoid saturation, then signal reliability is improved, but useful information during stimulation is lost
Solution Approach 1:
The system provides feedback about signal reliability through monitoring the test tone frequency. This allows the system to identify periods when sensing is unreliable due to saturation, while still maintaining continuous sensing capability. The feedback mechanism enables differentiation between reliable and unreliable sensing periods without completely blocking the sensing electrodes.
Solution Approach 2:
Instead of completely blocking the sensing electrodes during stimulation, the system applies partial action by continuing to sense but using the test tone monitoring to identify which portions of the sensed data are reliable. This approach captures more information than complete blocking would allow, while still maintaining data quality through selective validation.
Data Source
AI summary
Systems and method may be used for interfacing with a patient. Systems may include a plurality of electrodes in electrical communication with a processor. The processor may be configured to receive sense signals from electrodes and to determine the reliability of the received signal. A test tone signal comprising a test tone frequency may be applied, and the magnitude of the test tone frequency may be analyzed in the received signal. If it is determined that the magnitude of the test tone frequency is below a threshold, the system may take action, such as lowering the gain on an amplifier. Stimulation signals may be applied to the patient at a stimulation frequency simultaneously with one or both of receiving sense signals and providing the test tone signal.