Three-Electrode ECG Measurement for Simultaneous Limb Leads Without DRL
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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 causes power line interference, and require multiple electrodes and sequential measurements, leading to inconvenience and potential measurement discrepancies.
Innovation Solution
An electrocardiogram measurement apparatus using three dry electrodes, two amplifiers, and an electrode driver to measure two limb leads simultaneously, employing a band pass filter to concentrate power line interference current through one electrode, allowing accurate measurement without a DRL electrode.
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 requires cable connection
Solution Approach 1:
The patent extracts and eliminates the DRL electrode from the system by using an alternative approach. Instead of using a fourth DRL electrode connected via cable, the invention uses only three electrodes (two hand electrodes and one foot electrode) with a specific amplifier configuration that references both hand electrodes to measure two limb leads simultaneously, thereby removing the need for the DRL electrode and its associated cable connection.
Solution Approach 2:
The patent makes the foot electrode serve multiple functions. The left foot electrode (LE) is used both as a measurement electrode for Lead III (in conjunction with RA) and as a reference electrode for the amplifier circuit. This multi-functionality allows the system to achieve DRL-like interference rejection without requiring a separate DRL electrode, thus reducing device size and eliminating cable connections.
2Measurement precision
If multiple electrodes are used for simultaneous measurement of two limb leads, then measurement accuracy is improved, but device complexity and electrode quantity increase
Solution Approach 1:
The patent merges the functions of multiple electrodes and amplifiers into a compact configuration. By using three electrodes (RA, LA, LE) and two amplifiers where each amplifier references both hand electrodes, the system achieves simultaneous measurement of two limb leads (Lead I and Lead III) without requiring four separate electrodes and cables as in conventional DRL-based systems.
Solution Approach 2:
The patent changes the reference parameter of the amplifiers from a single-ended reference (ground) to a differential reference (both hand electrodes). This parameter change in the amplifier configuration allows the system to achieve common-mode rejection of power line interference while using only three electrodes, thereby simplifying the device while maintaining measurement precision.
3Device complexity
If sequential measurement of leads is performed, then device complexity is reduced, but measurement time increases and results may vary
Solution Approach 1:
The patent enables continuous simultaneous measurement of multiple limb leads by using two amplifiers operating in parallel. Each amplifier continuously measures a different lead (Lead I and Lead III) using the same three electrodes, allowing both leads to be captured at the exact same moment. This eliminates the sequential measurement process and ensures that both leads reflect the same physiological state without time delays or variations.
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.