Printed Flexible pH Sensor Using Silver Mirror Reaction

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Solution Overview

Problem

Traditional methods for manufacturing PH sensors on flexible substrates are hindered by the inability to withstand high temperatures, as glass electrodes are fragile and corrode easily, and metal electrodes require high-temperature sintering, making it difficult to produce flexible PH sensors effectively.

Innovation Solution

A printed flexible PH sensor is fabricated using a flexible substrate with a working electrode comprising a first silver layer formed by ink-jet printing, a second silver layer created through a silver mirror reaction, and a metal oxide layer on the end portion, along with a reference electrode having a silver chloride layer, all processed at temperatures below 60°C to avoid high-temperature sintering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional electroplating or sputtering methods are used to manufacture working electrodes and reference electrodes, then better conductivity and structure are achieved, but high-temperature sintering is required which cannot be withstood by flexible substrates

Engineering Contradiction:

Improveconductivity and structureVSAvoidsintering temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent changes the temperature parameter from high-temperature sintering to low-temperature processing (below 60°C) by using ink-jet printing followed by silver mirror reaction. This allows the flexible substrate to withstand the processing conditions while still achieving functional electrodes with adequate conductivity and structure.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal field (high-temperature sintering) with a chemical field (silver mirror reaction). Instead of using heat to sinter metal particles into conductive structures, the invention uses chemical reduction to deposit silver layers, eliminating the need for high-temperature processing that would damage the flexible substrate.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If glass electrodes are used as working electrodes, then PH sensing function is achieved, but they are fragile and corrode easily

Engineering Contradiction:

ImprovePH sensing functionVSAvoidfragility and corrosion resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent uses composite material structure combining flexible substrate, silver layers, and metal oxide layers to create a working electrode that replaces traditional glass electrodes. This composite structure provides both the PH sensing function and the mechanical flexibility, eliminating the fragility and corrosion issues of glass electrodes while maintaining sensing capability.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If ink-jet printing process is used to form silver layers, then manufacturing cost is reduced and flexibility is achieved, but conductivity and structural strength may be compromised

Engineering Contradiction:

Improvemanufacturing cost and flexibilityVSAvoidconductivity and structural strength

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by first forming a silver layer through ink-jet printing, then performing silver mirror reaction to deposit additional silver. This two-step approach ensures that the preliminary printed layer serves as a foundation that enhances both conductivity and structural strength, while maintaining the flexibility and cost advantages of the printing process.

Inventive Principle:

Principle #10Preliminary action

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 method reduces manufacturing costs, improves conductivity and structural strength, and allows for the production of flexible PH sensors that can withstand the demands of various applications, including food, environmental, and biomedical fields, while maintaining better structural density and reduced resistance.

Implementation Method 1

a second silver layer formed on the first silver layer by a silver mirror reaction

Methodology Applied

Scientific EffectSilver mirror reaction: Reduction

Data Source

PatentUS10520469B2Printed flexible sensors

Publication Date: 2019.12.31 WINBOND ELECTRONICS CORP

AI summary

A printed flexible PH sensor is provided. The printed flexible PH sensor includes a flexible substrate. A working electrode is disposed on the flexible substrate, and the working electrode includes a first silver layer formed on the flexible substrate by an ink-jet printing process, a second silver layer formed on the first silver layer by a silver mirror reaction, and a metal oxide layer disposed on the second silver layer of an end portion of the working electrode. A reference electrode is disposed on the flexible substrate, and the reference electrode includes the first silver layer and the second silver layer formed on the first silver layer, and a silver chloride layer totally covering the second silver layer. A method for fabricating the printed flexible PH sensor is also provided.