Planar Solid-State Reference Electrode for Miniaturized pH Sensing
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Solution Overview
Problem
Conventional pH sensors face challenges with miniaturization and dry storage of reference electrodes, as well as limitations in sensitivity and stability, particularly in continuous process monitoring and cost-effectiveness.
Innovation Solution
A planar solid-state reference electrode is developed using a pyrrole/RuOX/Si substrate with a polypyrrole layer, formed through electro-polymerization, which provides a stable and miniaturized pH sensing system with reduced sensitivity and ease of manufacturing, allowing for dry storage and integration with extended gate field effect transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional wet reference electrodes are used, then stable reference potential is achieved, but miniaturization and dry storage are prevented
Solution Approach 1:
The patent replaces the mechanical/chemical wet reference electrode system with a solid-state planar reference electrode based on electrochemical reactions at a solid electrode surface. The reference potential is generated through solid-state electrochemical reactions rather than liquid electrolyte contact, enabling miniaturization and dry storage while maintaining functional stability.
Solution Approach 2:
The patent changes the physical state parameter of the reference electrode from wet (liquid electrolyte) to dry (solid-state). This parameter change enables miniaturization by eliminating the need for liquid reservoirs and complex sealing structures, while the solid-state design allows for planar integration and dry storage capabilities.
2Duration of action of stationary object
If conventional reference electrodes are used, then stable reference potential is achieved, but immersion in buffer solution and long storage time are required
Solution Approach 1:
The patent replaces the immersion-based wet reference electrode with a solid-state planar design that does not require continuous contact with buffer solution. The solid-state structure maintains its reference potential stability through internal solid-state electrochemical reactions, eliminating the need for immersion storage and handling.
Solution Approach 2:
The solid-state planar reference electrode is designed to maintain its reference potential stability through self-contained solid-state electrochemical reactions. The structure includes integrated solid electrolyte and electrode materials that generate and maintain stable potential without requiring external buffer solution immersion or frequent reconditioning.
3Measurement precision
If ISFET structure is used, then pH sensing capability is achieved, but sensitivity and stability are limited
Solution Approach 1:
The patent merges the ISFET pH sensing structure with a solid-state planar reference electrode in a single integrated device. The ISFET provides pH-sensitive detection while the integrated solid-state reference electrode provides stable reference potential, combining both functions in one miniaturized sensor that achieves improved sensitivity and stability compared to conventional separate electrode systems.
Solution Approach 2:
The patent uses composite material structures combining ISFET semiconductor materials with solid-state reference electrode materials (solid electrolytes, conductive layers). This composite structure enables both pH sensitivity from the ISFET and stability from the solid-state reference system, achieving superior overall performance.
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 solution achieves stable and low pH sensitivity, enabling effective pH measurement with improved miniaturization and dry storage capabilities, suitable for continuous monitoring and cost-effective production.
Implementation Method 1
forming a polypyrrole layer on the solid-state conductive sensing layer by electro-polymerization
Implementation Method 2
the exposed silicon dioxide layer detects the Zeta potential produced from the aqueous solution such that the purpose of sensing the ion concentration in the aqueous solution can be achieved
Implementation Method 3
The ISFET is a semiconductor pH sensor in which the metal on the gate of the metal-oxide semiconductor field effect transistor (MOSFET) is removed to expose the silicon dioxide layer. When the ISFET is placed into an aqueous solution, the exposed silicon dioxide layer detects the Zeta potential produced from the aqueous solution
Data Source
AI summary
A reference pH sensor, the preparation and application thereof. The reference pH sensor is an extended gate field effect transistor (EGFET) structure and comprises a metal oxide semiconductor field effect transistor (MOSFET) on a semiconductor substrate, a sensing unit comprising a substrate, a solid-state conductive sensing layer on the substrate, and a polypyrrole layer on the solid-state conductive sensing layer, and a metal wire connecting the MOSFET and the sensing unit.