Pressure Sensor Self-Diagnosis via Parasitic Diode Contact Check
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Solution Overview
Problem
Existing pressure gauges lack a reliable method to verify uninterrupted contact of the measuring element, leading to potential faults that can disrupt pressure measurement.
Innovation Solution
A pressure measuring device utilizing a semiconductor substrate with a parasitic diode junction between n-type and p-type layers, connected to a switching unit and microcontroller, allows for a diagnostic mode to verify contact integrity by measuring forward voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant setup using a second measuring element or additional LED is employed to detect breaks in bond wires, then the reliability of fault detection is improved, but the device complexity increases
Solution Approach 1:
The measuring element uses its own parasitic diode junction to detect faults in its electrical connections. The microcontroller measures forward voltage across the parasitic diode to determine bond wire integrity, eliminating the need for separate diagnostic components and achieving self-diagnosis functionality
Solution Approach 2:
The parasitic diode junction, which is inherently present in the semiconductor substrate during manufacturing, is repurposed to serve dual functions: maintaining electrical contact during pressure measurement and enabling fault detection during diagnostic mode, thereby eliminating the need for separate diagnostic components
2Measurement precision
If the semiconductor substrate is set to its lowest potential and constant current or voltage is applied to verify connection integrity, then the precision of fault detection is improved, but the use of energy increases
Solution Approach 1:
The system alternates between pressure measurement mode and diagnostic mode. During diagnostic mode, constant current or voltage is applied to measure forward voltage across the parasitic diode for fault detection. This periodic switching allows precise fault detection while minimizing overall energy consumption by limiting diagnostic measurements to specific intervals
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 precise fault detection and localization of electrical connections, enhancing operational reliability and simplifying maintenance by automating fault diagnosis without redundant structures.
Implementation Method 1
the semiconductor substrate has a parasitic diode junction (body diode) that is not used during pressure measurement. The invention utilizes this diode junction to verify the uninterrupted contact of the measuring element intended for pressure measurement. For this purpose, a microcontroller detects a forward voltage between the n-type and p-type layers
Implementation Method 2
One method for pressure measurement is the use of the so-called piezoresistive effect. For this, the measuring element for detecting the pressure consists of a semiconductor substrate, preferably silicon, and a measuring bridge with at least one piezoresistive resistive track
Data Source
Figure 1~2
AI summary
The invention relates to a method for monitoring the function of a pressure gauge with a measuring element (1) comprising a semiconductor substrate (2) and a measuring bridge consisting of at least one piezoresistive resistive track, wherein the semiconductor substrate (2) has an n-type layer and a p-type layer, and four first connection pads (10, 20, 30, 40) for electrically contacting the measuring bridge are connected to the p-type layer. According to the invention, at least one of the four electrical leads (3) provided for contacting the measuring bridge is connected to a switching unit (4) configured to switch between a pressure measurement mode and a diagnostic mode, and the semiconductor substrate (2) has a further connection pad (50) that is connected to the n-type layer.A microcontroller (5) is configured to detect a forward voltage between the n-type and p-type layers by being connected at a point P to at least one of the four electrical lines (3) and, in diagnostic mode, measuring the voltage drop between this point P and the further connection pad (50). Furthermore, the invention relates to a pressure measuring device for functional monitoring.