Humidity Sensor With Open Cavity Corona Discharge
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Solution Overview
Problem
Existing relative humidity sensors rely on absorbent materials that can vary over time, leading to inaccurate measurements due to aging and environmental exposure, requiring recalibration and potentially causing delays in data availability.
Innovation Solution
A sensor design featuring electrodes and a counter-electrode in an open cavity, where a corona discharge voltage is applied to ionize the atmosphere, allowing direct measurement of relative humidity based on the voltage and temperature, eliminating reliance on absorbent materials and their variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If absorbent materials like polyimide are used to measure humidity, then the sensor can detect moisture levels, but the material characteristics change over time causing measurement inaccuracy
Solution Approach 1:
The patent extracts the measurement function from the absorbent material itself and transfers it to the surrounding atmosphere. By creating an open cavity that exposes electrodes directly to ambient air, the sensor measures humidity through corona discharge characteristics of the atmosphere rather than through material absorption properties, eliminating material degradation issues
Solution Approach 2:
The patent replaces the chemical/physical absorption mechanism of polyimide materials with an electrical field-based corona discharge mechanism. Instead of measuring electrical characteristics changes in absorbing material, the sensor measures current flow through ionized atmosphere, substituting a stable electrical field interaction for a degrading material-based measurement
2Reliability
If absorbent materials are used in humidity sensing, then moisture absorption can be detected, but recalibration is required over time due to material aging
Solution Approach 1:
The open cavity structure with exposed electrodes enables the sensor to continuously interact with ambient atmosphere, allowing real-time humidity measurements without requiring periodic recalibration or material replacement. The system serves itself by maintaining stable measurement capability through direct atmospheric exposure
3Quantity of substance
If polyimide material is exposed to high humidity environments, then moisture absorption occurs, but the material becomes oversaturated requiring heater drying time
Solution Approach 1:
The patent removes the absorbent material from the measurement system entirely, replacing it with direct atmospheric exposure. The open cavity allows the sensor to measure humidity in high humidity environments without saturation limitations or required drying periods, as the measurement is based on atmospheric ionization rather than material absorption capacity
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
This approach provides consistent, accurate relative humidity measurements regardless of environmental conditions or sensor age, reducing the need for recalibration and ensuring reliable data availability.
Implementation Method 1
a corona discharge voltage is applied to ionize the atmosphere
Implementation Method 2
ionize the atmosphere
Data Source
AI summary
In a described example, an apparatus includes: at least one electrode having a base on a first surface of a substrate and extending away from the base to an end; a counter-electrode spaced from the end of the at least one electrode, having a first conductive surface facing the end; and a package having a cavity containing the at least one electrode, the substrate, and the counter-electrode, the package having at least one opening configured to allow an atmosphere to enter the cavity.