Capacitive Humidity Sensor Two-Phase Potential Measurement
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Solution Overview
Problem
Capacitive humidity sensors face challenges in differentiating between condensation scenarios and humidity levels below 100% due to uncontrolled environmental impedance changes, leading to false measurements.
Innovation Solution
A capacitive humidity sensor design that applies different electrical potentials to its electrodes during two phases of measurement, ensuring the potential difference between the electrodes complies with specific conditions to minimize parasitic capacitances and differentiate between condensation and humidity scenarios, thereby reducing false readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional capacitive humidity sensor uses a single measurement phase with fixed electrical potentials, then the sensor structure is simple and easy to manufacture, but the sensor cannot differentiate between condensation scenarios and humidity levels below 100%, leading to false measurements
Solution Approach 1:
The patent applies periodic action by implementing a two-phase measurement cycle where electrical potentials are alternated between phases. In the first phase, specific potentials are applied to charge the sensing layer, and in the second phase, different potentials are applied to measure the capacitance. This periodic switching enables the sensor to distinguish between condensation and high humidity by comparing measurements from both phases, thereby improving measurement precision without requiring fundamentally new hardware components.
Solution Approach 2:
The patent employs dynamics by making the electrical potentials applied to the electrodes dynamic rather than static. The measurement circuit switches between different potential configurations during the two measurement phases, allowing the sensor to adapt its measurement approach based on the phase. This dynamic potential application enables differentiation between condensation scenarios and high humidity conditions, resolving the measurement ambiguity while maintaining a relatively simple sensor structure.
2Reliability
If the sensor applies different electrical potentials to the second electrode in two measurement phases, then the sensor can adapt functionality for specific measurement scenarios and reduce false readings, but the measurement circuit becomes more complex
Solution Approach 1:
The patent applies parameter changes by varying the electrical potential parameters applied to the electrodes during different measurement phases. Specifically, the potential of the second electrode is changed between the first and second measurement phases, while the first electrode maintains a reference potential. This parameter variation allows the sensor to detect changes in capacitance that indicate condensation versus high humidity, improving reliability. The implementation uses standard circuit components with controlled potential switching, managing complexity through systematic parameter management rather than fundamental architectural changes.
3Measurement precision
If the sensor uses a two-phase measurement with changing electrical potentials, then the sensor can detect condensation scenarios and improve sensitivity range, but the measurement process takes more time
Solution Approach 1:
The patent implements periodic action through a rapidly cycling two-phase measurement approach. The sensor alternates between the first measurement phase (charging) and the second measurement phase (sensing) in quick succession, completing multiple measurement cycles within a short time frame. This periodic operation enables condensation detection through comparison of phases while minimizing the time penalty, as the switching between phases is performed electronically at high speed rather than requiring sequential manual measurements.
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 sensor effectively differentiates between condensation and humidity scenarios, reducing false measurements and improving sensitivity by adapting its functionality to specific measurement conditions.
Implementation Method 1
The measurement circuit is configured to measure the capacitance of the electrode structure by applying, at a first measurement phase, a first pair of electrical potentials to the first electrode and the second electrode
Implementation Method 2
The sensing layer may have in particular a humidity sensitive permittivity and may hence be embodied as humidity sensitive layer
Data Source
AI summary
A capacitive sensor includes a substrate and an electrode structure including at least a first electrode, a second electrode and a sensing layer arranged between the first electrode and the second electrode. The sensor further includes a measurement circuit configured to measure the capacitance of the electrode structure by applying, at a first measurement phase, a first pair of electrical potentials including a first electrical potential of the first electrode and a first electrical potential of the second electrode to the first electrode and the second electrode by applying, at a second measurement phase, a second pair of electrical potentials including a second electrical potential of the first electrode and a second electrical potential of the second electrode to the first electrode and the second electrode. The first electrical potential of the second electrode and the second electrical potential of the second electrode are different from each other.