Moisture Detection Element with Segmented Electrodes
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Solution Overview
Problem
Conventional alcohol detectors lack the ability to distinguish between human exhalation and external air, leading to potential unauthorized use, and are not robust enough for mobile and environmental variations, resulting in sensor errors due to dust and size limitations.
Innovation Solution
A moisture detection element with a comb-shaped application and detection electrode configuration, an auxiliary electrode, and an insulating substrate, which uses AC voltage to enhance sensitivity and reduce errors by adhering to the principle of moisture detection through output voltage changes, while being designed to be compact and resistant to dust interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitance change type humidity sensor is used to monitor moisture changes, then the sensor can detect moisture in the air, but it cannot accurately detect saturated water vapor in human exhalation and is susceptible to dust interference
Solution Approach 1:
The sensor surface is divided into multiple electrode fingers (comb-shaped electrodes) with insulating layers between them. This segmentation allows the sensor to detect moisture through capacitance changes while the insulating layers prevent dust particles from causing short circuits between electrodes, thereby maintaining detection accuracy and reliability simultaneously
Solution Approach 2:
An insulating layer is introduced as an intermediary between the electrode fingers and the external environment. This insulating layer enables the sensor to maintain electrical isolation while still detecting moisture capacitance changes, and it acts as a protective barrier against dust interference, resolving the contradiction between detection precision and reliability
2Volume of moving object
If fine pattern electrodes are used to reduce sensor size for mobile use, then the device becomes compact and portable, but sensor errors occur due to dust in the atmosphere
Solution Approach 1:
The electrode structure is segmented into multiple narrow fingers with gaps between them, allowing the use of fine pattern electrodes for compact size while the insulating layers between fingers prevent dust-induced short circuits, thus maintaining reliability in mobile applications
Solution Approach 2:
Thin insulating films are used to cover the electrode fingers, providing protection against dust interference while maintaining the compact fine pattern structure. The thin film configuration enables small sensor size without sacrificing reliability in mobile environments
3Reliability
If conventional alcohol detectors measure moisture to determine human exhalation, then unauthorized use can be prevented, but the device size increases and power consumption rises due to additional components like fans
Solution Approach 1:
The moisture detection element serves multiple functions: it detects moisture in exhalation to prevent unauthorized use, and its compact design integrates directly into the alcohol detector without requiring additional fans or complex airflow control systems, thereby maintaining exhalation recognition accuracy while reducing device size and power consumption
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 effectively differentiates human exhalation from external air, improves robustness, reduces sensor errors, and enables a compact, low-power consumption design suitable for mobile use, enhancing the reliability of exhalation recognition.
Implementation Method 1
a capacitance change type humidity sensor (which is configured to measure the conductivity and capacitance change of the sensor element)
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3C
AI summary
A moisture detection element includes: an insulating substrate of an insulating material (4); an application part (2) which is formed on the insulating substrate and to which a voltage is applied; an output part (3) which is formed on the insulating substrate and configured to output a voltage signal corresponding in response to a current flowing through an electric path via water molecules (11) adhering to a surface of the insulating substrate under the voltage applied to the application part; and a conductive film (61) which is electrically insulated from the application part and the output part and is provided on the insulating substrate. An insulating film (62) of an insulating material is provided on the application part (2), the output part (3), and the conductive film (61). Dust (12) may adhere to the insulating film (62) and thus a short circuit between the application electrode (2) and the output part (3) may be prevented.