Shielded Electrode Noise Reduction for Simultaneous Cardiac and Pulse Wave Measurement
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Solution Overview
Problem
The existing configuration of biomedical electrodes, where a shield is disposed around an interconnect wire to a buffer, can lead to deterioration of cardiac potential signal quality during simultaneous measurement of pulse wave and cardiac potential due to noise pickup from the pulse wave signal.
Innovation Solution
An electronic device with a first electrode and a pulse wave sensor closer to the first electrode, featuring a first amplifying unit, interconnect wire, shield member, and a shield potential controller with different buffer circuits to apply specific signals for shielding the electrode and interconnect wire at predetermined times, reducing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield member is disposed around the interconnect wire to reduce noise, then the signal quality deteriorates during simultaneous measurement of pulse wave and cardiac potential, but without the shield member, noise from the pulse wave sensor interferes with the cardiac potential measurement
Solution Approach 1:
The shield potential controller applies a first generation signal from the first buffer circuit to the shield member before the pulse wave sensor starts measuring, and switches to a second generation signal from the second buffer circuit at the measurement time point. This preliminary action prepares the shield member to counteract noise before it affects the cardiac potential measurement, resolving the contradiction between noise reduction and signal quality maintenance.
Solution Approach 2:
The system dynamically switches the drive current of the buffer circuit based on measurement timing. The shield member is driven by a first buffer circuit with a first drive current before measurement, and switched to a second buffer circuit with a second drive current (different from the first) during measurement. This dynamic adjustment allows the shield to effectively counteract noise at different stages without compromising cardiac potential signal quality.
2Ease of operation
If the pulse wave sensor is disposed closer to the first electrode for convenient measurement, then the ease of operation improves, but the cardiac potential signal quality deteriorates due to increased noise pickup
Solution Approach 1:
The shield member acts as an intermediary between the pulse wave sensor and the first electrode/interconnect wire. By applying generation signals from the buffer circuits to the shield member, it creates an electromagnetic shield that intercepts and counteracts noise from the pulse wave sensor before it can couple into the cardiac potential measurement circuit, enabling close placement without signal quality degradation.
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
This configuration effectively reduces the deterioration of cardiac potential signal quality during simultaneous measurement by shielding the electrode and interconnect wire with a higher drive current buffer circuit at the appropriate times, improving signal quality and usability.
Implementation Method 1
a first shield member that shields the first electrode and the first interconnect wire
Implementation Method 2
a shield potential controller including a first buffer circuit and a second buffer circuit... the first buffer circuit generates a first generation signal... the second buffer circuit generates a second generation signal
Data Source
AI summary
An information processing system includes first and second electrodes for measuring cardiac potential, a pulse wave sensor that is disposed closer to the first electrode than to the second electrode and that measures a pulse wave, a buffer that amplifies a signal acquired by the first electrode, an interconnect wire that electrically connects the first electrode to a terminal of the buffer, a shield that shields the first electrode and the interconnect wire, and a shield potential generator that includes a first buffer circuit and a second buffer circuit having a larger drive current than the first buffer circuit and that starts applying, to the shield, a first generation signal generated by the first buffer circuit based on the acquired signal before a predetermined time point when the pulse wave is measured and starts applying a second generation signal generated by the second buffer circuit at the predetermined time point.