Capillary Microfluidic Electrode for Stable Biopotential Measurement

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Solution Overview

Problem

Existing electrode apparatuses for biopotential measurements face challenges in adhering well to the body and maintaining a stable electrolyte layer, which can lead to poor measurement accuracy and discomfort due to the use of adhesives and gel electrolytes that dry out.

Innovation Solution

The electrode apparatus comprises a substrate with a first microfluidic channel made of electrically conductive material, a second microfluidic channel exposed to the external environment for liquid absorption by capillary action, and conduits connecting the two channels, allowing for self-adhesion and continuous liquid supply without adhesives or gel electrolytes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If adhesives and gel electrolytes are used to make electrodes adhere to the body, then adhesion is improved, but comfort deteriorates and reliability worsens due to drying out

Engineering Contradiction:
ImproveadhesionVSAvoidmeasurement stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The electrode apparatus uses capillary channels that automatically absorb and transport electrolyte solution from the body surface to the electrode contact points through capillary action, eliminating the need for external adhesives and gel electrolytes that require manual application and maintenance

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces the mechanical adhesive bonding system with a capillary-driven fluid transport system, where microfluidic channels with specific surface properties automatically draw and deliver electrolyte solution to maintain reliable electrical contact without mechanical fastening

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If gel electrolytes are used to enable biopotential measurements, then measurement capability is improved, but duration of action deteriorates as the gel dries out

Engineering Contradiction:
Improvebiopotential measurement qualityVSAvoidelectrolyte layer stability
Core Design Contradiction:
Measurement precisionVSDuration of action of moving object

Solution Approach 1:

The capillary channels continuously absorb fresh electrolyte solution from the body surface and transport it to the electrode contacts, ensuring an uninterrupted supply of conductive medium that maintains measurement quality over extended periods without drying out

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent changes the physical state of the electrolyte from a pre-applied gel to a dynamically replenished liquid solution transported through capillary channels, transforming the system from a static electrolyte layer to a continuously refreshed conductive medium

Inventive Principle:
Principle #35Parameter changes

3Strength

If adhesives are used to secure electrodes to the body, then adhesion is improved, but comfort deteriorates

Engineering Contradiction:
ImproveadhesionVSAvoiddiscomfort
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The electrode apparatus achieves secure attachment through the capillary action mechanism that automatically draws electrolyte solution through microchannels, creating a self-bonding effect that eliminates the need for uncomfortable adhesive materials

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent employs capillary channels with specific pore sizes and surface properties that enable automatic fluid absorption and transport, using the porous structure to create both mechanical attachment and functional electrolyte delivery without traditional adhesives

Inventive Principle:
Principle #31Porous materials

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 solution enables a high-density, sustainable, and comfortable electrode interface for long-term biopotential measurements, maintaining low impedance and reducing noise, while eliminating the need for adhesives and gel electrolytes.

Implementation Method 1

the second microfluidic channel is exposed to the external environment and configured to absorb liquid by capillary action

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP3753485B1Electrode apparatuses and methods of forming electrode apparatuses
Publication Date: 2025.05.07 NOKIA TECHNOLOGIES OY
  • EP3753485B1 patent drawingFigure 1
  • EP3753485B1 patent drawingFigure 2A~3B
  • EP3753485B1 patent drawingFigure 4A~5C

AI summary

An electrode apparatus comprising: a substrate, the substrate comprising: a first microfluidic channel; a second microfluidic channel; and at least one conduit extending between the first microfluidic channel and the second microfluidic channel; wherein the first microfluidic channel and the at least one conduit comprise electrically conductive material, and wherein the second microfluidic channel is exposed to the external environment and configured to absorb liquid by capillary action.