Coulometric Humidity Sensor Gel Electrolyte Viscosity Control
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Solution Overview
Problem
Existing humidity sensors face challenges with non-homogeneous surface wetting due to high surface tension of hygroscopic materials, leading to uneven layer thickness, positional dependence, and difficulties in transportation and operation.
Innovation Solution
A humidity sensor with a non-conductive substrate and electrodes, where the hygroscopic material's viscosity is increased by adding solid particles, such as nanoparticles, allowing for more homogeneous wetting and improved reproducibility and transportability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hygroscopic material is applied to the sensor surface, then humidity sensing function is achieved, but non-homogeneous wetting and uneven layer thickness occur due to high surface tension
Solution Approach 1:
The patent changes the physical parameter of the hygroscopic material by adjusting its viscosity (e.g., through temperature control or additive selection) to optimize wetting behavior. This parameter modification enables homogeneous surface coverage while maintaining the material's humidity-sensing functionality, resolving the contradiction between achieving sensing function and ensuring layer uniformity.
Solution Approach 2:
The patent introduces an intermediary substance or processing step (such as a surfactant, binder, or controlled atmosphere during application) that mediates between the hygroscopic material and the sensor surface. This intermediary reduces surface tension effects and facilitates uniform distribution of the hygroscopic material, thereby achieving both functional coverage and manufacturing precision.
2Reliability
If hygroscopic material is applied to the sensor surface, then humidity sensing function is achieved, but the sensor can only be operated in the calibrated spatial orientation due to material migration
Solution Approach 1:
The patent creates a composite material system by combining the hygroscopic material with a matrix material or structural support that provides mechanical stability. This composite structure prevents material migration while preserving the hygroscopic properties, allowing the sensor to function reliably in various orientations without requiring recalibration.
Solution Approach 2:
The patent applies different materials or structures to different regions of the sensor assembly. Specifically, the hygroscopic material is localized in a constrained geometry (such as a recess or between electrodes) where it performs its sensing function, while surrounding structural elements provide orientation-independent mechanical support. This local differentiation enables both sensing functionality and operational versatility.
3Reliability
If hygroscopic material is applied to the sensor surface, then humidity sensing function is achieved, but transport is hindered due to material flow and potential edge overflow
Solution Approach 1:
The patent performs preliminary actions during the manufacturing process to prevent transport problems before they occur. This includes applying the hygroscopic material in a controlled state (e.g., low viscosity or constrained geometry) that prevents flow during handling, and only later activating its full hygroscopic functionality. This preliminary constraint enables easy transport while maintaining sensing function.
Solution Approach 2:
The patent uses a thin film or encapsulating structure that contains the hygroscopic material during transport. This flexible constraint allows the material to be moved and handled easily without flowing or overflowing, while still permitting moisture diffusion for sensing operation. The film acts as a temporary barrier that is permeable to water vapor but impermeable to bulk material flow.
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 enables reliable, reproducible, and position-independent humidity measurements, eliminating the need for edge barriers and enhancing sensor transportability.
Implementation Method 1
water molecules are absorbed by a hygroscopic material
Implementation Method 2
A voltage is applied via two separate electrodes that are in contact with the hygroscopic material. This triggers an electrolytic dissociation of the water molecules into hydrogen and oxygen.
Data Source
Figure 1~2
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Figure 4
AI summary
The invention relates to a coulometric humidity sensor (1) suitable for measuring atmospheric humidity, comprising at least one non-conductive planar substrate (3), at least two spaced-apart electrodes (4.1, 4.2) arranged on a planar side of the substrate (3), and a hygroscopic material (5) applied planarly to the planar side of the non-conductive substrate (3) and the electrodes (4.1, 4.2), connecting the electrodes (4.1, 4.2), wherein the viscosity of the hygroscopic material (5) is increased by at least one admixed solid. The invention further relates to an associated method for manufacturing a humidity sensor (1).