Capacitive Sensor Self-Test via ASIC Reference Capacitance Evaluation
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Solution Overview
Problem
Conventional capacitive pressure sensors face challenges in detecting malfunctions, particularly due to environmental exposure that can cause liquid-induced offsets in measurements, and existing self-test methods require additional detection components.
Innovation Solution
A capacitive sensor system incorporating a MEMS element with a Wheatstone bridge circuit and an ASIC element that ascertains and evaluates reference capacitance values to detect short-circuit resistances, allowing for a self-test without additional detection components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional self-test methods using additional detection components are used, then malfunction detection capability is improved, but device complexity increases
Solution Approach 1:
The existing capacitive sensor components (Wheatstone bridge circuit and ASIC element) are made multi-functional by enabling them to perform both normal pressure measurement and self-test functions. The ASIC element evaluates capacitance values of the Wheatstone bridge to detect short circuits, allowing the same hardware to serve dual purposes without adding dedicated detection components.
Solution Approach 2:
The capacitive sensor performs self-diagnosis by using its own internal components to detect malfunctions. The ASIC element monitors the capacitance values of the Wheatstone bridge circuit and automatically detects short circuits, enabling the device to self-test without external intervention or additional specialized components.
2Duration of action of moving object
If the sensor is exposed to the environment for extended use, then functionality and measurement capability are maintained, but measurement precision deteriorates due to liquid-induced offsets
Solution Approach 1:
The system performs preliminary self-tests by evaluating capacitance values before normal measurement operations. The ASIC element continuously monitors the Wheatstone bridge circuit parameters to detect short circuits early, preventing corrupted measurements from being recorded and maintaining precision throughout the service life.
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 a simple and effective self-test for capacitive sensors, allowing for the detection of potential measurement errors and faults, such as short circuits, without requiring additional hardware, thereby ensuring reliable operation over the sensor's lifespan.
Implementation Method 1
an ASIC element, wherein the ASIC element is designed to ascertaining a measured value of at least one reference capacitance of the capacitive Wheatstone bridge circuit
Implementation Method 2
a MEMS element comprising a Wheatstone bridge circuit
Data Source
AI summary
A capacitive sensor. The capacitive sensor includes: a MEMS element including a capacitive Wheatstone bridge circuit; and an ASIC element, wherein the ASIC element is designed to ascertain a measured value of at least one reference capacitance of the capacitive Wheatstone bridge circuit, wherein actuation signals for ascertaining the reference capacitance are applicable to a respective supply line of the capacitive Wheatstone bridge circuit, wherein the ASIC element is designed to read and evaluate the measured values of the reference capacitances, wherein a resistance value of at least one short-circuit resistance of the capacitive sensor is ascertainable from the values of the reference capacitances.