Diamond-Like Carbon Coatings for ECG Sensor Electrodes
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Solution Overview
Problem
Existing coatings for conductive electronic device structures face challenges in achieving desired color brightness and optical performance across different operating environments and geometries, which can lead to unsatisfactory aesthetic appearance and deterioration of sensor performance.
Innovation Solution
A visible-light-reflecting coating with adhesion and transition layers, an opaque coloring layer, and a thin-film interference filter featuring a diamond-like carbon (DLC) uppermost layer is applied to conductive substrates, such as sensor electrodes, to impart a desired color and reduce noise in ECG data by minimizing Faraday current and double layer capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a coating is applied to conductive structures to achieve desired color brightness, then the aesthetic appearance is improved, but the optical performance may deteriorate across different operating environments and geometries
Solution Approach 1:
The coating is divided into multiple functional layers including an opaque coloring layer and a thin-film interference filter with diamond-like carbon layers, where each layer performs a specific function to achieve both color brightness and optical performance consistency across different geometries and environments
Solution Approach 2:
The coating uses composite material structures combining different materials (opaque coloring layer, diamond-like carbon layers, interference filter layers) to simultaneously achieve desired color appearance and maintain consistent optical performance across varying operating conditions and substrate geometries
2Illumination intensity
If a coating is applied to conductive structures, then the aesthetic appearance is improved, but sensor performance may deteriorate due to noise and interference
Solution Approach 1:
The diamond-like carbon layers serve as intermediary elements between the opaque coloring layer and the sensor electrode, providing optical interference effects for color appearance while simultaneously reducing electrical noise and Faraday current interference to maintain sensor data accuracy
Solution Approach 2:
The coating structure provides different local properties at different layers: the opaque coloring layer provides color appearance, while the diamond-like carbon layers provide electrical noise reduction and optical interference, allowing each layer to optimize its specific function without compromising the other
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 coating achieves a consistent, desired color appearance while enhancing the accuracy of ECG data by reducing noise and ensuring robust performance across varying geometries and environments.
Implementation Method 1
a visible-light-reflecting coating that reflects particular wavelengths of visible light... a thin-film interference filter on the opaque coloring layer
Implementation Method 2
the DLC layer may mitigate Faraday current between the sensor electrode and skin
Implementation Method 3
may reduce double layer capacitance between the sensor electrode and skin
Implementation Method 4
may reduce the water cone angle of moisture on the coating
Data Source
AI summary
An electronic device such as a wristwatch may be provided with conductive structures. The conductive structures may include a sensor electrode for an electrocardiogram (ECG) sensor. A coating may be disposed on the sensor electrode to reflect particular wavelengths of visible light so that the sensor electrode exhibits a desired color. The coating may include adhesion and transition layers on the sensor electrode, an opaque coloring layer on the adhesion and transition layers, and a thin-film interference filter on the opaque coloring layer. The thin-film interference filter may have an uppermost diamond-like carbon (DLC) layer. The DLC layer may contribute to the color response of the coating while concurrently minimizing noise in ECG waveforms gathered by the ECG sensor using the sensor electrode.