Micro Machined Ion-Selective Sensor With Polymer Electrolyte
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Solution Overview
Problem
Current miniaturized ion-selective sensors face limitations in long-term stability and frequent recalibration due to signal drift and degradation, especially when exposed to harsh environments, and are often limited to single-use applications.
Innovation Solution
A micro machined chip with three micro channels for analyte, electrolyte, and ion-selective liquid membrane solutions, integrated with a porous layer in a fully enclosed reservoir, allowing for a fully integrated ion-sensor on a microchip that can be stored in a dry environment and has improved stability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ion-selective electrodes with liquid aqueous internal electrolyte are used, then the sensor can perform ion measurement, but the sensor experiences signal drift and degradation leading to frequent recalibration and limited lifetime
Solution Approach 1:
The patent changes the physical state of the internal electrolyte from liquid aqueous phase to solid-state polymer matrix. The polymer electrolyte membrane contains ion-conductive polymer chains that maintain structural integrity and prevent phase changes, eliminating signal drift associated with liquid electrolyte evaporation or crystallization. This parameter change from liquid to solid state directly improves sensor stability and lifetime.
Solution Approach 2:
The patent employs composite material structure combining polymer matrix with ion-conductive additives. The composite polymer electrolyte membrane integrates multiple components: polymer chains providing structural framework, ion-conductive salts providing charge transport, and plasticizers enhancing flexibility. This composite structure achieves both mechanical stability and ion conductivity, resolving the contradiction between sensor reliability and operational duration.
2Volume of moving object
If miniaturized ion-selective sensors are used, then the sensor size is reduced for portable applications, but the sensor becomes fragile and cannot withstand harsh environments
Solution Approach 1:
The patent utilizes a thin-film polymer electrolyte membrane that provides mechanical protection while maintaining miniaturization. The polymer film acts as a flexible barrier that protects the internal electrolyte from environmental contaminants while withstanding mechanical stress. This thin-film approach enables sensor miniaturization without sacrificing mechanical robustness, as the polymer matrix itself provides structural integrity.
Solution Approach 2:
The patent designs a disposable sensor where the entire miniaturized device with polymer electrolyte membrane is intended for single use. This approach accepts that miniaturized sensors may have limited durability but optimizes for cost-effectiveness and ease of replacement. The disposable design allows use in harsh environments where replacement sensors can be easily deployed, eliminating the need for robust long-term durability.
3Ease of manufacture
If liquid membrane is stored in reservoir for extended periods, then the sensor can be prepared in advance, but the liquid membrane ages and degrades leading to changes in interfacial equilibrium
Solution Approach 1:
The patent changes the physical state of the membrane from liquid to solid polymer form. The polymer electrolyte membrane maintains its structural integrity over extended storage periods without the phase changes that plague liquid membranes. This parameter change from liquid to solid state eliminates aging-related degradation while still allowing for sensor preparation and calibration before deployment.
Solution Approach 2:
The patent performs preliminary formation of the polymer electrolyte membrane structure during manufacturing, where the polymer matrix is already in place and ready for ion-conductive salt incorporation. This preliminary action eliminates the need for extended storage of liquid membrane solutions, as the solid polymer structure can be prepared in advance and stored stably without degradation.
4Device complexity
If coated wire electrodes and CHEMFETS are used, then the sensor structure is simplified, but the sensor still experiences long-term drift problems due to stagnating liquids at the sensing membrane level
Solution Approach 1:
The patent incorporates a flow channel system that enables continuous fluid flow through the sensor structure. This hydraulic approach prevents liquid stagnation by maintaining controlled flow through the polymer electrolyte membrane and sensing regions. The flow mechanism eliminates the drift problems associated with stagnant liquids while maintaining a relatively simple sensor structure based on the polymer membrane platform.
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 provides a low-cost, long-term stable ion-selective sensor capable of multiple uses, avoiding issues related to aging of the liquid membrane and reducing contact-related disruptions, enabling precise ion concentration measurements.
Implementation Method 1
a liquid membrane micro channel adapted to draw an ion-selective liquid membrane solution
Implementation Method 2
a porous layer arranged in said reservoir
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
Ion-selective sensor (6) comprising a micro-machined chip with an analyte micro-channel (2), adapted to draw an analyte solution and a first liquid membrane micro channel (3) adapted to draw a liquid membrane solution, and an first electrolyte micro channel (1), adapted to draw an analyte solution. The ion-selective sensor (6) comprises a first substrate (100) and a second substrate (200) comprising each a structured surface to form, after assembly of said substrates the analyte micro-channel (2), the first electrolyte micro channel (1) and the first liquid membrane micro channel (3), each provided with their respective inlet and outlet.