Contactless ECG Biometric Recognition via Capacitive Sensing

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Solution Overview

Problem

Existing biometric recognition systems are limited by requiring direct contact with the user, using metallic electrodes, and being suitable only for momentary validation, which distracts users and is not suitable for continuous recognition, especially in environments with intense motion or electromagnetic noise.

Innovation Solution

A device comprising a computational unit and a sensory unit that measures ECG signals continuously without direct contact or metallic electrodes, using non-metallic conductive elements or capacitive sensors, allowing for continuous biometric recognition even in motion-intensive environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional ECG measurement methods using metallic electrodes and direct contact are used, then measurement precision is improved, but ease of operation deteriorates and user distraction increases

Engineering Contradiction:
ImproveECG signal measurement precisionVSAvoiduser convenience and continuity of operation
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces the mechanical contact-based ECG measurement system (metallic electrodes requiring direct skin contact) with a contactless capacitive sensing system. The sensory unit uses capacitive coupling to detect ECG signals through the body without physical contact, thereby maintaining measurement precision while dramatically improving ease of operation and eliminating user distraction.

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

Solution Approach 2:

The patent introduces air or insulation material as an intermediary between the sensory unit and the user's body. This intermediary layer enables capacitive coupling to transmit ECG signals without direct contact, resolving the contradiction by allowing accurate measurement while eliminating the need for uncomfortable or distracting physical contact.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If momentary biometric validation is performed, then authentication accuracy is improved, but productivity deteriorates due to task interruption

Engineering Contradiction:
Improveauthentication accuracyVSAvoiduser task continuity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent transforms momentary biometric validation into continuous biometric recognition. The system continuously monitors ECG signals in the background without requiring user initiation or task interruption, maintaining authentication reliability while eliminating productivity loss from repeated stop-and-validate cycles.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system performs automatic continuous authentication without requiring user action. The ECG signals are captured and processed automatically in the background, allowing the authentication process to serve itself without distracting the user from their primary tasks.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If direct contact with metallic electrodes is required, then measurement precision is improved, but object-affected harmful factors worsen due to motion interference

Engineering Contradiction:
ImproveECG signal qualityVSAvoidmotion and electromagnetic noise interference
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical contact-based measurement system with a contactless capacitive sensing system. This substitution eliminates motion artifacts and skin contact issues while maintaining ECG signal quality, thereby improving robustness in motion-intensive environments without sacrificing measurement precision.

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

Solution Approach 2:

By introducing air or insulation material as an intermediary, the system creates a stable capacitive coupling that is less sensitive to motion and electromagnetic interference than direct skin contact with metallic electrodes. This intermediary layer filters out harmful factors while preserving the essential ECG signal.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables uninterrupted biometric recognition, reducing user distraction and improving usability in various environments, while eliminating the need for direct contact and metallic electrodes, thus enhancing the reliability and convenience of biometric authentication.

Implementation Method 1

using non-metallic conductive elements or capacitive sensors

Methodology Applied
Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentEP3973869B1Device and method for continuous biometric recognition based on electrocardiographic signals
Publication Date: 2025.04.23 INST SUPERIOR TECH
  • EP3973869B1 patent drawingFigure 1
  • EP3973869B1 patent drawingFigure 2
  • EP3973869B1 patent drawingFigure 3a~3b

AI summary

The present invention is related with the field of signal measurement for biometric recognition purposes, and refers to a computational unit and a sensory unit designed to measure electrocardiographic (ECG) signals in a continuous fashion, guaranteeing that the biometric recognition is performed in an uninterrupted way whenever the device is used, with the purpose of enabling the automated recognition or validation of the identity of its wearer. The sensory unit has an electronic module through which the ECG is acquired. Its operating principle can be based in the electrical conductivity, in which case it requires contact with the skin of the user, or in any kind of capacitive or mechanical element, in which case it does not require any direct contact with the user. The device can be used in alternative or as a complement to existing systems that only perform a momentary identity check. It can be applied to vehicles, tablet computers or analogous contexts.