Wearable Biosignal Acquisition via Randomized Electrode Switching
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Solution Overview
Problem
Current wearable devices for biological signal acquisition suffer from low signal quality and poor reliability due to motion artifacts and limited sensing channels, which restrict their effectiveness in monitoring and controlling electronic devices for health care and entertainment.
Innovation Solution
The use of a set of electrodes configured to acquire signals from a subject's epidermis, with a switch to select and direct signals to fewer channels, and a processor to analyze these signals, allowing for the determination of electric source positions and amplitudes, while also injecting currents to improve signal quality and correct for motion artifacts through capacitive coupling and impedance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sensing channels is increased to improve signal quality, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent segments the signal acquisition process into multiple phases where different subsets of electrodes are activated sequentially. Instead of using all N electrodes simultaneously through N channels, the system divides electrode usage into time-separated groups, allowing M < N channels to capture signals from different electrode combinations at different times, thereby reducing channel requirements while maintaining measurement precision
Solution Approach 2:
The patent implements dynamic electrode configuration where the switch matrix reconfigures which electrodes are connected to which channels in real-time. This dynamic switching allows the same M channels to serve multiple electrode pairs sequentially, transforming a static N-channel requirement into a dynamic M-channel solution that achieves equivalent or superior signal quality through temporal multiplexing
2Measurement precision
If more electrodes are used to improve signal acquisition, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs periodic switching of electrode-channel connections, where the switch matrix cycles through different electrode configurations in a predetermined sequence. This periodic action allows M channels to periodically sample signals from different electrode pairs, effectively utilizing N electrodes over time without requiring N simultaneous channels, thus improving signal quality while controlling device complexity
3Device complexity
If the number of channels is reduced to lower cost, then device complexity is reduced, but signal quality deteriorates
Solution Approach 1:
The patent performs preliminary signal routing through a switch matrix that pre-configures electrode connections to channels based on the desired measurement configuration. By establishing the optimal electrode-channel mapping in advance through controlled switching, the system ensures that even with M < N channels, the full information content from N electrodes can be captured across multiple time steps, preventing signal quality deterioration despite channel reduction
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 approach enhances signal quality, reduces the number of required channels, and increases the robustness of wearable devices to movement artifacts, leading to improved performance and cost-effectiveness, enabling longer battery life and more accurate gesture recognition.
Implementation Method 1
a set of N electrodes, configured to be located in proximity to an epidermis of a subject, and to acquire signals generated by electric sources within the subject
Implementation Method 2
a switch, configured to select, repetitively and randomly, M signals from the N electrodes and to direct the M signals to the M channels
Implementation Method 3
a processor, configured to activate the switch, and to receive and analyze the M signals from the M channels so as to determine respective positions of the electric sources within the subject
Implementation Method 4
the processor is configured to activate the switch so as to inject respective predetermined currents from the sources between selected pairs of the N electrodes
Implementation Method 5
at least one of the electrodes is capacitively coupled to the epidermis
Data Source
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AI summary
Apparatus, including a set of N electrodes (22), configured to be located in proximity to an epidermis (24) of a subject, and to acquire signals generated by electric sources within the subject. The apparatus also includes a set of M channels, configured to transfer the signals, where M is less than N, and a switch (40), configured to select, repetitively and randomly, M signals from the N electrodes and to direct the M signals to the M channels. The apparatus further includes a processor (28), configured to activate the switch, and to receive and analyze the M signals from the M channels so as to determine respective positions of the electric sources within the subject.