Biosensor Laminate Moisture Barrier for Impedance Stability

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Biosensors experience increased and varying electrode impedance due to non-uniform drying of the electrode surface when attached to the skin for extended periods, leading to noise and unreliable signal detection.

Innovation Solution

A laminate for biosensors is designed with a pressure-sensitive adhesive layer, a substrate layer, a probe, and a moisture barrier layer that overlaps with the probe. This configuration suppresses moisture permeation through the laminate, maintaining uniform moisture at the probe interface and preventing dryness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If the biosensor is attached to the skin for a long period, then the electrode can continuously detect biosignals, but the moisture evaporates and the electrode surface gets dry non-uniformly causing excessive increase and large variation in electrode impedance

Engineering Contradiction:
Improveusage durationVSAvoidelectrode impedance stability
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent applies local quality by positioning the moisture barrier layer specifically at the lower face of the probe where moisture retention is most critical for maintaining low electrode impedance. This localized approach prevents non-uniform drying at the electrode-skin interface while allowing other parts of the biosensor to function normally. The moisture barrier layer is strategically placed only where needed to prevent moisture evaporation, thereby maintaining reliable electrical contact throughout extended usage periods.

Inventive Principle:
Principle #3Local quality

2Reliability

If moisture is added to lower electrode impedance, then signal quality improves, but the moisture permeates through the laminate and evaporates over time causing non-uniform drying

Engineering Contradiction:
Improveelectrode impedanceVSAvoidmoisture distribution uniformity
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces a moisture barrier layer as an intermediary between the probe and the surrounding laminate structure. This intermediary layer selectively manages moisture by preventing excessive permeation through the laminate while still allowing controlled moisture presence at the electrode-skin interface. The moisture barrier layer acts as a mediator that maintains stable moisture levels without causing non-uniform distribution, thereby preserving both low impedance and uniform composition throughout the usage period.

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

The laminate effectively reduces and stabilizes electrode impedance, enhancing signal reliability and consistency over time by maintaining optimal moisture levels at the electrode-skin interface.

Implementation Method 1

a moisture barrier layer disposed so as to overlap with the probe when projected in the thickness direction... the moisture barrier layer can suppress moisture present at the interface between the living body and the probe to permeate the laminate for biosensor in the thickness direction

Methodology Applied
Scientific EffectMoisture barrier: Semipermeable Membrane

Implementation Method 2

a pressure-sensitive adhesive layer for attaching to a living body

Methodology Applied
Scientific EffectPressure-sensitive adhesion: Adhesive

Data Source

PatentEP3766413B1Biosensor laminate and biosensor
Publication Date: 2025.04.30 NITTO DENKO CORP
  • EP3766413B1 patent drawingFigure 1
  • EP3766413B1 patent drawingFigure 2A~2B
  • EP3766413B1 patent drawingFigure 3

AI summary

A laminate for biosensor includes a pressure-sensitive adhesive layer for attaching to a surface of a living body; and a substrate layer disposed on the upper face of the pressure-sensitive adhesive layer, wherein the laminate for biosensor includes a probe disposed at the lower face of the laminate for biosensor, and a moisture barrier layer disposed so as to overlap with the probe when projected in the thickness direction.