pH Sensor With Integrated Ion Reservoir for Stable Reference Potential
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Solution Overview
Problem
Existing pH sensors face challenges with unstable reference electrode potentials due to ion concentration changes, requiring frequent recalibration and replenishment, which is costly and impractical in certain applications, and miniaturized sensors are expensive to manufacture.
Innovation Solution
A pH sensor design with an integrated reference electrode and ion reservoir material, such as a chloride salt solution, encapsulated in a cavity to maintain constant chloride activity, combined with a method of manufacturing that incorporates the reference electrode in the packaging process, ensuring stability and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reference electrode with buffer solution is used to maintain stable reference potential, then the reference electrode potential stability is improved, but the buffer solution ions leak away over time requiring frequent replenishment and recalibration
Solution Approach 1:
The patent extracts the ion reservoir function from the traditional buffer solution and implements it as a solid-state ion reservoir layer (e.g., AgCl layer) that provides ions without leaking. This separates the ion supply function from the liquid buffer, eliminating the leakage problem while maintaining reference potential stability.
Solution Approach 2:
The patent changes the physical state of the ion reservoir from liquid (buffer solution) to solid (ion reservoir layer), fundamentally altering how ions are supplied. This parameter change eliminates ion leakage while maintaining the reference electrode's ability to provide stable potential over extended periods.
2Volume of moving object
If miniaturized pH sensors with integrated reference electrodes are manufactured using IC processes, then sensor miniaturization is achieved, but the manufacturing cost becomes prohibitive
Solution Approach 1:
The patent segments the sensor manufacturing into two parts: the sensing device can be miniaturized using IC processes, while the reference electrode is manufactured separately using cost-effective screen printing or paste deposition techniques on a carrier substrate. This segmentation allows each component to be optimized for its specific manufacturing requirements.
Solution Approach 2:
The patent merges the separately manufactured sensing device and reference electrode into an integrated sensor assembly through encapsulation and electrical connections. This combining approach achieves miniaturization benefits while avoiding the prohibitive costs of fully integrated IC manufacturing.
3Device complexity
If complex IC manufacturing processes are used for integrated pH sensors, then sensor integration is achieved, but the device complexity and cost increase
Solution Approach 1:
The patent segments the manufacturing processes into simple carrier-based reference electrode fabrication and separate sensing device assembly. The reference electrode is created using simple screen printing or paste deposition on a carrier, avoiding complex IC processes while achieving functional integration through encapsulation and electrical connections.
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, stable pH sensor with extended lifetime by maintaining constant chloride ion concentration, reducing the need for frequent recalibration and simplifying the manufacturing process, making it suitable for low-end applications like the food industry.
Implementation Method 1
an ion reservoir material (44) sharing at least one ion type with said reference electrode material (42)
Implementation Method 2
the reference potential E is defined by the Nernst equation
Data Source
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AI summary
Disclosed is a pH sensor comprising a carrier (10) comprising a plurality of conductive tracks and an exposed conductive area (40) defining a reference electrode connected to one of said conductive tracks; a sensing device (30) mounted on the carrier and connected at least one other of said conductive tracks; an encapsulation (20) covering the carrier, said encapsulation comprising a first cavity (22) exposing a surface (32) of the sensing device and a second cavity (24) exposing the exposed conductive area, said second cavity comprising a reference electrode material (42) and an ion reservoir material (44) sharing at least one ion type with said reference electrode material, the reference electrode material being sandwiched between the exposed conductive area and the ion reservoir material. A method of manufacturing such a pH sensor is also disclosed.