Three-Electrode ECG Measurement Without a DRL Electrode
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Solution Overview
Problem
Existing electrocardiogram measurement devices face challenges in simultaneously measuring two limb leads without using a DRL electrode, which increases size and discomfort, and struggle to effectively remove power line interference with dry electrodes while maintaining a compact and cable-free design.
Innovation Solution
The device employs three dry electrodes, two amplifiers, and an electrode driver to measure two limb leads simultaneously, using a band pass filter to concentrate power line interference current through one electrode, minimizing its impact on signal measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a DRL electrode is used to remove power line interference, then power line interference is reduced, but the device size increases and user comfort deteriorates
Solution Approach 1:
The patent removes the DRL electrode from the system entirely, extracting the harmful element that caused device complexity increase. Instead of adding a fourth electrode for DRL, the invention uses only three electrodes (two hand electrodes and one foot electrode) and eliminates the need for DRL through alternative signal processing methods, thereby reducing device size and improving user comfort while still addressing power line interference.
Solution Approach 2:
The patent converts the harmful power line interference into a manageable signal by using it as a reference for notch filtering. The interference signal, rather than being eliminated through additional hardware (DRL electrode), is captured and used to create a filter that removes only the problematic frequency components while preserving the ECG signal, thus solving the interference problem without increasing device complexity.
2Productivity
If three electrodes are used to measure two limb leads simultaneously, then measurement capability is improved, but power line interference removal becomes more difficult
Solution Approach 1:
The patent makes the three electrodes serve multiple functions: the two hand electrodes and one foot electrode are used not only for ECG measurement but also as reference points for power line interference rejection. The foot electrode, in particular, serves dual purposes by providing both ECG signal measurement and a reference path for interfering currents, allowing the system to achieve both measurement capability and interference rejection with the same hardware.
Solution Approach 2:
The patent introduces digital signal processing (notch filtering and adaptive filtering) as an intermediary between the electrode signals and the final ECG output. This intermediary processing stage removes power line interference from the three-electrode signals without requiring additional electrodes, effectively mediating between the simplified hardware configuration and the need for clean ECG signals.
3Ease of operation
If dry electrodes are used for cable-free design, then ease of operation is improved, but power line interference increases
Solution Approach 1:
The patent changes the electrical parameters of the dry electrodes by optimizing their surface area, material properties, and contact pressure to reduce electrode impedance. By adjusting these parameters, the system compensates for the inherently higher impedance of dry electrodes, thereby reducing power line interference while maintaining the cable-free advantage of dry electrode technology.
Solution Approach 2:
The patent uses digital filtering algorithms as intermediaries to process the signals from dry electrodes. These algorithms (notch filters and adaptive filters) specifically target and remove power line interference frequencies from the dry electrode signals, allowing the system to maintain ease of operation with cable-free dry electrodes while eliminating the increased power line interference through software-based correction.
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 allows for accurate, simultaneous measurement of two limb leads and additional calculated leads, effectively reducing power line interference without a DRL electrode, ensuring user convenience and compactness.
Implementation Method 1
using a band pass filter to concentrate power line interference current through one electrode
Data Source
AI summary
The present invention relates to an electrocardiogram measurement apparatus (measurement sensor) which can be used in combination with a smartphone by an individual. The electrocardiogram measurement apparatus according to the present invention comprises: two amplifiers for receiving electrocardiogram signals from a first electrode and a second electrode; one electrode driving unit; a third electrode for receiving an output of the electrode driving unit; an A/D converter connected to an output terminal of each of the two amplifiers and converting analog signals into digital signals; a microcontroller for receiving the digital signals from the A/D converter; and a communication means for transmitting the digital signal, wherein: the microcontroller is supplied with power from a battery; the microcontroller controls the A/D converter and the communication means; and each of the two amplifiers amplifies one electrocardiogram signal so as to simultaneously measure two electrocardiogram signals.