Shared Electrode Wearable for Skin Resistance and Capacitance

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Solution Overview

Problem

Current wearable devices lack efficient methods for consistently measuring skin resistance and capacitance, which are essential for monitoring physiological parameters like perspiration and emotional states, and often fail to determine if the device is properly mounted on the skin.

Innovation Solution

A wearable device with electrical contacts that protrude from a housing, featuring a capacitor and electronic switch, allows for the measurement of skin resistance when the switch is closed and capacitance when open, enabling accurate determination of these parameters and ensuring the device operates correctly when mounted on the skin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate electrodes are used for skin resistance and capacitance measurements, then measurement functions are complete, but device complexity and component quantity increase

Engineering Contradiction:
Improvemeasurement functionsVSAvoidcomponent quantity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a dual-function electrode system where the same first and second electrodes serve both skin resistance measurement and skin capacitance measurement functions. The control unit switches between different measurement modes by applying different excitation signals to the shared electrodes, eliminating the need for separate electrode sets and reducing overall device complexity while maintaining full measurement capability

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the skin resistance measurement electrodes and skin capacitance measurement electrodes into a single shared electrode pair. By combining these functions into one electrode system with intelligent control switching, the device reduces component quantity and simplifies the overall structure while preserving both measurement functions through time-division or signal-division multiplexing

Inventive Principle:
Principle #5Merging (Combining)

2Productivity

If skin resistance and capacitance are measured simultaneously, then measurement efficiency is high, but measurement accuracy deteriorates due to signal interference

Engineering Contradiction:
Improvemeasurement efficiencyVSAvoidmeasurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent employs periodic switching between skin resistance measurement mode and skin capacitance measurement mode, controlled by a control unit that applies different excitation signals at different time intervals. This periodic alternation prevents signal interference between the two measurement types while maintaining high overall measurement efficiency through systematic time-division multiplexing

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent segments the measurement process into distinct time intervals or signal phases, where skin resistance measurement and skin capacitance measurement are performed separately in sequence rather than simultaneously. The control unit manages this segmentation by switching between different measurement circuits or signal configurations, ensuring each measurement type receives dedicated measurement time without interference

Inventive Principle:
Principle #1Segmentation

3Device complexity

If the device structure is simplified with shared electrodes, then device complexity is reduced, but difficulty of detecting and measuring increases due to signal interference

Engineering Contradiction:
Improveelectrode configurationVSAvoidsignal discrimination
Core Design Contradiction:
Device complexityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements a dynamic control system that actively switches the electrode configuration and signal routing based on the current measurement mode. The control unit dynamically adjusts the circuit connections, excitation signal frequencies, and measurement parameters to optimize signal detection for either skin resistance or skin capacitance measurement, preventing interference through real-time dynamic adaptation

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent introduces a control unit as an intermediary between the shared electrodes and the measurement circuits. This control unit acts as a mediator that manages signal routing, applies appropriate excitation signals, and processes measurements for both skin resistance and skin capacitance functions, resolving the detection difficulty by intelligently coordinating the shared electrode system

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

This solution enables reliable and continuous monitoring of skin resistance and capacitance, allowing for effective tracking of physiological parameters and ensuring the device operates efficiently and safely by determining proper mounting.

Implementation Method 1

a capacitor and an electronic switch in series with the capacitor, wherein the series combination of the capacitor and the electronic switch is electronically coupled to the first and second electrical contacts

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

first and second electrical contacts protruding from the housing... such that the first and second electrical contacts contact skin at the external body surface

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3160338B1Sharing a single electrode between skin resistance and capacitance measurements
Publication Date: 2020.12.02 VERILY LIFE SCIENCES LLC
  • EP3160338B1 patent drawingFigure 1
  • EP3160338B1 patent drawingFigure 2A~2B
  • EP3160338B1 patent drawingFigure 3A~3B

AI summary

Wearable devices are described herein including a housing and a mount configured to mount the housing to an external surface of a wearer. The wearable devices further include first and second electrical contacts protruding from the housing and configured such that the electrical contacts can be used to measure a Galvanic skin resistance of skin proximate to the electrical contacts when the wearable device is mounted to the external surface of the wearer. The electrical contacts are additionally configured to measure a capacitance between electrical contacts. The measured capacitance between the electrical contacts could be related to a capacitance of skin proximate to the electrical contacts when the wearable device is mounted to the external surface of the wearer. The wearable devices further include an electronically switched capacitor connected between (he electrical contacts that can be operated to enable the Galvanic skin resistance and capacitance measurements described above.