Capacitive Humidity Sensor Parasitic Capacitance Control
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Solution Overview
Problem
Capacitive-based humidity sensors face challenges in reducing and controlling sensitivity without increasing parasitic capacitance, leading to inaccurate readings, especially at high humidity levels and varying environmental conditions.
Innovation Solution
A humidity sensor apparatus is designed with a silicon substrate, silicon dioxide, TiW, gold, and porous platinum layers, along with parasitic capacitance components to control sensitivity without increasing the size of the sensor, utilizing existing parasitic capacitances to adjust the total capacitance value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensitivity of capacitive humidity sensors is reduced by making component parts thinner, then measurement precision is improved, but the sensor becomes more sensitive to mechanical stress and environmental variations
Solution Approach 1:
The patent changes the physical parameters of the sensor components, specifically making the component parts thinner to reduce parasitic capacitance and improve measurement precision. This parameter change allows the sensor to achieve faster response times and more accurate humidity measurements across extreme ranges of humidity, temperature, and pressure.
2Adaptability or versatility
If additional parasitic capacitance is added to control sensitivity, then sensitivity control is improved, but the total size of the capacitor increases
Solution Approach 1:
The patent converts the harmful effect of parasitic capacitance into a beneficial control mechanism. By intentionally designing and utilizing parasitic capacitance components, the invention achieves sensitivity control without requiring additional capacitor size. The parasitic capacitance that was previously considered a source of error is now harnessed to adjust and optimize the sensor's sensitivity characteristics.
3Speed
If thin component parts are used to avoid stress problems, then measurement speed is improved, but the sensor becomes more vulnerable to mechanical shifts
Solution Approach 1:
The patent optimizes the thickness parameter of component parts to achieve a balance between measurement speed and structural stability. By carefully controlling the dimensional parameters of thin components, the sensor achieves fast response times while maintaining adequate mechanical integrity and resistance to environmental stress.
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 configuration allows for precise and accurate humidity measurements across a wide range of humidity, temperature, and pressure conditions by effectively managing sensitivity and avoiding additional parasitic capacitance, reducing errors and mechanical stress.
Implementation Method 1
The absorption of water into a sensor structure causes a number of physical changes in the active polymer. These physical changes can be transduced into electrical signals which are related to the water concentration in the polymer
Implementation Method 2
Two of the most common physical changes are the change in resistance and the change in dielectric constant, which can be respectively translated into a resistance change and a capacitance change
Data Source
AI summary
A humidity sensor apparatus and method of forming the same. A substrate can be provided upon which a plurality of humidity sensing components are disposed to form a humidity sensor thereof. Each humidity sensing component generally includes an associated particular parasitic capacitance. This parasitic capacitance is utilized to reduce and/or control a sensitivity and a total capacitance value associated with the humidity sensor without increasing a size of the humidity sensor and/or humidity sensor components (e.g., capacitors).