Mixer-Based Lead-On Detection for High-Impedance Dry Electrodes
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Solution Overview
Problem
Small dry electrodes in portable medical devices suffer from high impedance, leading to detection errors in lead-on detection circuitry due to power line common mode interference and electrode tissue offset, causing inaccurate determination of electrode contact with the human body and increased power consumption.
Innovation Solution
A lead-on detection circuitry comprising a mixer-based receiver and a duty-cycle controller, which generates a clock signal to transmit signals to the electrodes, allowing accurate detection of electrode contact by mixing the signals and reducing power consumption through controlled enablement of circuit components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If smaller dry electrodes are used in portable medical devices, then the device portability and comfort are improved, but the electrode impedance increases causing detection errors
Solution Approach 1:
The patent introduces a transmitter and receiver system as intermediaries between the small dry electrode and the detection circuitry. The transmitter sends a test signal through the electrode, and the receiver detects the signal, using this intermediate signaling mechanism to overcome the high impedance limitation of small electrodes and enable accurate lead-on detection.
2Measurement precision
If the lead-on detection circuitry is always enabled to detect electrode contact, then the detection accuracy is improved, but the power consumption increases
Solution Approach 1:
The patent implements periodic action by enabling the lead-on detection circuitry only at specific intervals or under certain conditions rather than continuously. The transmitter and receiver are activated periodically to send and detect test signals, allowing accurate electrode contact detection while significantly reducing overall power consumption compared to continuous operation.
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
The solution enables accurate detection of electrode contact with minimal power consumption by filtering out interference and offset, reducing detection errors and prolonging device battery life.
Implementation Method 1
The mixer-based receiver is configured to perform a mixing operation based on the clock signal and the transmitting signal to generate an output signal
Data Source
AI summary
The present invention provides a lead-on detection circuitry of a biopotential acquisition system. The lead-on detection circuitry includes an input terminal, a duty-cycle controller, a transmitting signal generator and a mixer-based receiver. The duty-cycle controller is configured to generate a first clock signal. The transmitting signal generator is configured to generate a transmitting signal to the input terminal according to the first clock signal. The mixer-based receiver is configured to perform a mixing operation based on the first clock signal and the transmitting signal to generate an output signal, wherein the output signal indicates if an electrode of the biopotential acquisition system is in contact with a human body, and the electrode is coupled to the input terminal.