Hydroxide Ion Sensor Using Layered Double Hydroxide Conductivity
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Solution Overview
Problem
Existing methods for measuring hydroxide ion concentration, such as pH titration, pH meters, and chromatography, face challenges in achieving high accuracy, ease of use, and cost-effectiveness, with pH meters being inaccurate and chromatography requiring complex setup and maintenance.
Innovation Solution
A device comprising an insulating substrate, insulating composite layers, electrodes, and a layered double hydroxide layer with high OH− ion conductivity, coupled with a semiconductor layer and protective layer, to measure hydroxide ion concentration by varying conductivity based on ion concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pH titration method is used, then measurement accuracy is improved, but operation complexity increases requiring skilled personnel
Solution Approach 1:
The patent replaces the mechanical/manual pH titration process with an electronic field-effect transistor-based sensing system. The FET device with layered double hydroxide layer directly converts hydroxide ion concentration into electrical signals (current or voltage), eliminating the need for manual titration operations while maintaining high measurement accuracy.
Solution Approach 2:
The patent changes the measurement parameter from pH (hydrogen ion concentration) to direct hydroxide ion concentration detection. By using a layered double hydroxide layer with high OH− ion conductivity in the FET structure, the device directly responds to hydroxide ion concentration through changes in electrical conductivity, providing accurate and straightforward measurement without complex titration procedures.
2Ease of operation
If pH meter is used, then ease of operation is improved, but measurement accuracy deteriorates
Solution Approach 1:
The patent changes the sensing mechanism from potential difference measurement (pH meter) to conductivity-based measurement using a layered double hydroxide layer. This layer provides high OH− ion conductivity that directly correlates with hydroxide ion concentration, enabling accurate measurement while maintaining ease of operation through simple electrical signal detection.
Solution Approach 2:
The patent employs a composite structure combining layered double hydroxide layer with field-effect transistor components. This composite material approach creates a device that is both easy to operate (like a pH meter) and highly accurate (improving upon pH meter limitations) by leveraging the high ionic conductivity of the layered double hydroxide material.
3Measurement precision
If chromatography method is used, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential function of hydroxide ion detection from the complex chromatography system. By isolating the key mechanism (ion-conducting layer response to hydroxide ions) and implementing it in a simple FET structure, the invention eliminates the need for separation columns, solvent systems, and complex chromatography apparatus while retaining accurate measurement capability.
Solution Approach 2:
The patent replaces expensive, fragile chromatography equipment with a simple, inexpensive FET-based sensor that can be easily manufactured and disposed of. The layered double hydroxide layer provides the necessary functionality without requiring costly chromatography infrastructure, making the measurement system both accurate and cost-effective.
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 quick and accurate measurement of hydroxide ion concentration with high sensitivity and low cost, suitable for various water types including river, sea, and industrial waste water, contributing to water quality monitoring.
Implementation Method 1
a layered double hydroxide layer having an OH− ion conductivity of 1×10−5 S/cm or more is provided between the insulating composite layer and the liquid storage portion
Data Source
AI summary
Provided are an apparatus and a method for measuring a concentration of hydroxide ions which are capable of easily and quickly measuring the concentration of the hydroxide ions with high accuracy and measuring the concentration of hydroxide ions at relatively low cost. An insulating substrate, at least one insulating composite layer, and a liquid storage portion capable of holding an ion-containing liquid are provided, the insulating composite layer includes a pair of electrodes and a semiconductor layer in contact with the pair of electrodes, and a layered double hydroxide layer having an OH-ion conductivity of 1×10−5 S/cm or more is provided between the insulating composite layer and the liquid storage portion.