Environmental Sensor Parasitic Capacitance Detection for Material Deposits
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Solution Overview
Problem
Pressure sensors are susceptible to inaccuracies due to liquid contact, which can alter pressure readings by increasing mass, and existing self-test methods are inadequate for detecting and addressing such issues.
Innovation Solution
An environmental sensor with a MEMS element and ASIC element connected via electrical conductors, utilizing an evaluation circuit to ascertain parasitic capacitance for detecting material deposits like liquids, which changes permittivity and parasitic capacitance, allowing for self-testing and potential countermeasures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pressure sensors are exposed to the external environment, then the sensor can detect environmental conditions, but liquids can come into contact with the sensor causing offsets in pressure readings
Solution Approach 1:
The patent converts the harmful effect of liquid contact into a beneficial detection mechanism by utilizing the changed dielectric constant of liquid environments. The sensor detects material deposits through capacitance changes caused by liquid contact, transforming the previously harmful interference into a useful detection signal for identifying sensor contamination.
Solution Approach 2:
The patent introduces an intermediary detection mechanism using capacitive electrodes and dielectric constant changes as a mediator between the liquid environment and the pressure measurement system. This intermediary approach allows indirect detection of liquid contamination through electrical property changes rather than direct mechanical contact.
2Reliability
If self-tests are performed by exciting a MEMS element, then sensor functionality can be checked, but the detection of material deposits remains insufficient
Solution Approach 1:
The patent makes the electrical conductors serve multiple functions: they act as both signal transmission pathways and as capacitive sensing electrodes for material deposit detection. By utilizing existing conductors for dual purposes, the system achieves enhanced detection capability without adding separate dedicated sensing elements.
Solution Approach 2:
The patent detects material deposits by monitoring changes in electrical parameters (capacitance) of the conductors. The evaluation circuit measures capacitance values of the electrical conductors, and changes in these parameters indicate the presence of material deposits, enabling sensitive detection through parameter monitoring.
3Difficulty of detecting and measuring
If additional electrical conductors are added for parasitic capacitance measurement, then material deposit detection sensitivity is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent makes the electrical conductors serve multiple functions: they act as both signal transmission pathways and as capacitive sensing electrodes for material deposit detection. By utilizing existing conductors for dual purposes, the system achieves enhanced detection capability without adding separate dedicated sensing elements.
Solution Approach 2:
The patent merges the signal transmission function and material deposit detection function into a single integrated system using the same electrical conductors. The evaluation circuit measures capacitance values of the existing conductors, combining communication and sensing functions to avoid adding separate dedicated sensing elements.
4Ease of operation
If heating elements are used to evaporate water droplets, then liquid removal capability is improved, but energy consumption and device complexity increase
Solution Approach 1:
The patent enables the sensor system to detect and respond to liquid contamination through its own electrical conductors and evaluation circuitry. The system performs self-diagnosis and can trigger appropriate responses without requiring external heating elements or additional liquid removal mechanisms, achieving self-service functionality.
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
Enables effective detection and removal of material deposits, ensuring sensor functionality by using existing conductors to save space and improve sensitivity, with self-testing capabilities to prevent consequential damage.
Implementation Method 1
the evaluation circuit is designed to ascertain and evaluate a parasitic capacitance of the further electrical conductor, in order to detect a material deposit on the environmental sensor
Implementation Method 2
a parasitic capacitance can be ascertained by a capacitance measurement by means of the evaluation circuit of the ASIC element using at least one further electrical conductor
Implementation Method 3
This exploits a changing permittivity at the environmental sensor due to material deposition, which can be accompanied by a change in the parasitic capacitance
Data Source
AI summary
An environmental sensor. The environmental sensor includes: a MEMS element; an ASIC element which is electrically conductively connected to the MEMS element via at least two electrical conductors, in particular bonding wires. The ASIC element and/or a substrate on which the MEMS element and/or the ASIC element are arranged includes at least one further electrical conductor. The ASIC element includes an evaluation circuit connected to the further electrical conductor. The evaluation circuit is configured to ascertain and evaluate a parasitic capacitance of the further electrical conductor, in order to detect a material deposit on the environmental sensor.