Flexible pH Sensor for High-Pressure Measurement
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Solution Overview
Problem
Existing pH sensors are not suited for operation under extreme pressure conditions and in electrically noisy environments, leading to unreliable measurements due to mechanical fragility, pressure-induced changes in reaction equilibria, and interference from feed-through wires.
Innovation Solution
A pH sensor design utilizing a combination of reverse osmosis membranes and a proton conducting membrane to selectively filter hydrogen ions, allowing for accurate measurement of pH in high-pressure environments, with electrodes made from materials like gold or platinum, and a flexible insulating material to maintain pressure equivalence between the sample and surroundings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional pH electrodes are used under high pressure, then pH measurement is possible at atmospheric pressure, but the device fails under extreme pressure conditions exceeding 150 MPa due to mechanical fragility
Solution Approach 1:
The patent employs flexible membranes (reverse osmosis membranes and proton conducting membranes) instead of rigid glass electrode structures. These flexible films can withstand extreme pressures up to 850 MPa while maintaining their functional properties, eliminating the mechanical fragility issue of conventional glass electrodes.
Solution Approach 2:
The sensor uses composite membrane structures combining reverse osmosis membranes with proton conducting membranes. This composite approach creates a pressure-resistant structure that maintains selective ion permeability under extreme pressure conditions, solving both mechanical strength and measurement accuracy requirements.
2Reliability
If feed-through wires are used in pressurized experimental set-ups, then electrical connection is achieved, but electrical interference occurs resulting in noisy signals
Solution Approach 1:
The patent removes feed-through wires from the pressurized environment entirely. Instead, electrical connections are made outside the pressure vessel, eliminating the source of electrical interference and noisy signals while maintaining reliable electrical connectivity for the pH measurement system.
3Measurement precision
If conventional pH electrodes are used under high pressure, then initial measurements can be obtained, but reproducibility is poor requiring up to eight cycles of pressurization before consistent results
Solution Approach 1:
The patent changes the fundamental material parameters from conventional glass electrode materials to pressure-stable membrane materials. This parameter change ensures that the sensor response remains consistent and reproducible from the first pressurization cycle, eliminating the need for multiple conditioning cycles required by conventional electrodes.
4Measurement precision
If glass pH electrodes are used, then pH measurement is possible, but the fragile nature of glass limits use under high pressures above 150 MPa
Solution Approach 1:
The patent replaces fragile glass electrodes with flexible membrane structures that can withstand pressures up to 850 MPa. The flexible nature of these membranes allows them to deform elastically under pressure without breaking, maintaining both measurement capability and pressure resistance.
Solution Approach 2:
The membrane-based sensor design creates a more durable replacement for fragile glass electrodes. While individual membranes have limited lifetimes, the overall system reliability is dramatically improved, and the sensors can be easily replaced without complex calibration procedures required by conventional electrodes.
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 reliable pH measurement across a wide pressure range (up to 850 MPa) with reduced noise interference, facilitating accurate and reproducible readings even in complex and opaque samples.
Implementation Method 1
a first reverse osmosis membrane disposed in the interior passage; a second reverse osmosis membrane disposed in the interior passage
Implementation Method 2
a proton conducting membrane disposed between the first reverse osmosis membrane and the second reverse osmosis membrane
Implementation Method 3
a flexible insulating material retains its flexibility in the pressure range of from about 0.1 MPa to about 850 MPa
Implementation Method 4
The electrical conductivity of an electrolytic solution is a function of the mobilities of each of the constituent ions
Implementation Method 5
The electromotive force so generated by this cell may be calibrated against the pH of the sample
Data Source
AI summary
A sensor for measuring the pH of a solution of the present invention includes: (a) a tubular body portion constructed from a flexible electrically-insulating material, the tubular body portion having an interior passage; (b) a first reverse osmosis membrane disposed in the interior passage; (c) a second reverse osmosis membrane disposed in the interior passage; (d) a proton conducting membrane disposed between the first reverse osmosis membrane and the second reverse osmosis membrane in the interior passage; (e) a first electrode; and (f) a second electrode.