ECG Electrode Carbon Coating for Wear Resistance and Signal Quality

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Solution Overview

Problem

Stainless steel and titanium alloy substrates used in ECG electrodes for smart devices suffer from low hardness and poor wear resistance, leading to degradation and failure over time, affecting electrocardiogram monitoring capability.

Innovation Solution

A doped graphite-like carbon film is applied to the electrode substrate, incorporating first nano-crystals with weak carbon-bonding elements (Cu, Ag, Au, Al) for enhanced conductivity and second nano-crystals with strong carbon-bonding elements (Cr, W, Ti) for increased hardness and wear resistance, with a transition layer to improve bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If stainless steel or titanium alloy is used as substrate material of the ECG electrode, then the electrode can be manufactured with basic structural integrity, but the electrode exhibits low hardness and poor wear resistance leading to degradation over time

Engineering Contradiction:
ImprovehardnessVSAvoidwear resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent applies composite materials by combining graphite-like carbon film with metal substrate (stainless steel or titanium alloy). The graphite-like carbon layer provides high hardness and wear resistance, while the metal substrate provides structural integrity and electrical conductivity. This composite structure resolves the contradiction between hardness and wear resistance

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the physical and chemical parameters of the coating material by using graphite-like carbon with specific structural characteristics (amorphous structure with graphitic domains). This parameter change enables the coating to achieve both high hardness and good wear resistance simultaneously

Inventive Principle:
Principle #35Parameter changes

2Strength

If graphite-like carbon film is applied to enhance hardness and wear resistance, then the electrode achieves high hardness, but the conductivity in thickness direction may be reduced

Engineering Contradiction:
ImprovehardnessVSAvoidconductivity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent applies local quality by creating a graphite-like carbon film with specific local structural characteristics on the electrode surface. The coating has amorphous structure with graphitic domains that provide both hardness and electrical conductivity pathways, ensuring local optimization of both mechanical and electrical properties

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent optimizes the thickness parameter of the graphite-like carbon film to be in the range of 0.5-5 micrometers. This parameter change ensures that the coating is thin enough to maintain electrical conductivity while thick enough to provide sufficient hardness and wear resistance

Inventive Principle:
Principle #35Parameter changes

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 ECG electrode achieves high conductivity, hardness, and wear resistance, ensuring prolonged service life and reliable electrocardiogram signal quality.

Implementation Method 1

an outer surface of an electrode substrate of the ECG electrode is plated with a doped graphite-like carbon film

Methodology Applied
Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentEP4335372B1ECG electrode and preparation method therefor, and electronic device
Publication Date: 2026.01.28 HUAWEI TECH CO LTD
  • EP4335372B1 patent drawingFigure 1~2
  • EP4335372B1 patent drawingFigure 3

AI summary

This application provides an ECG electrode. The ECG electrode includes an electrode substrate and a doped graphite-like carbon film located on an outer surface of the electrode substrate. The doped graphite-like carbon film includes graphite-like carbon, and first nano-crystals and second nano-crystals that are embedded in the graphite-like carbon. The first nano-crystal includes a weak carbon-bonding element. The weak carbon-bonding element has a part that exists in a form of a metallic elementary substance. The first nano-crystal includes a columnar structure. The columnar structure extends in a thickness direction of the doped graphite-like carbon film. The second nano-crystal includes a strong carbon-bonding element. The strong carbon-bonding element bonds with the carbon element in the graphite-like carbon through a chemical bond. The second nano-crystals are distributed between adjacent and spaced columnar structures. The ECG electrode provided in this application has high hardness and excellent wear resistance while ensuring excellent electrocardiography signal quality. In addition, this application further provides a fabrication method for the ECG electrode and an electronic device using the ECG electrode.