Pressure Sensor with Longitudinal Grooves for Stress Concentration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pressure sensors face challenges in sensitivity and temperature variability, particularly in applications like common rail injection systems, where large temperature fluctuations affect measurement accuracy.
Innovation Solution
A pressure sensor design featuring a carrier chip with longitudinal grooves and a bias voltage circuit, where the sensor elements are arranged between the grooves to concentrate mechanical stress and reduce temperature sensitivity, using piezoresistive resistors or field effect transistors in a Wheatstone bridge configuration, with adjustable supply voltage to compensate for temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the carrier chip thickness is reduced to increase sensitivity, then the sensitivity of the pressure sensor is improved, but the mechanical strength and durability of the carrier chip deteriorate
Solution Approach 1:
The carrier chip is segmented by introducing longitudinal grooves that divide the chip structure into multiple regions. This segmentation creates stress concentration zones that enhance sensitivity while the remaining solid portions maintain mechanical strength. The grooves effectively partition the chip without completely thinning it, resolving the contradiction between sensitivity and strength.
Solution Approach 2:
The carrier chip exhibits non-uniform thickness distribution with thinner regions between the grooves and thicker regions at the grooves themselves. This local quality variation allows the thinner areas to be more sensitive to pressure changes while the thicker groove regions provide structural support and maintain overall mechanical strength.
2Measurement precision
If piezoresistive resistors are used in the sensor element, then the temperature sensitivity increases, but the measurement accuracy under temperature variations deteriorates
Solution Approach 1:
A bias voltage circuit is implemented that provides temperature-dependent compensation voltage to the piezoresistive resistors. The circuit monitors temperature variations and adjusts the bias voltage accordingly, creating a feedback mechanism that compensates for temperature-induced resistance changes and maintains measurement accuracy across varying temperatures.
Solution Approach 2:
The bias voltage parameter is dynamically changed based on temperature conditions. By adjusting the voltage parameter in response to temperature variations, the system compensates for the increased temperature sensitivity of piezoresistive resistors, thereby maintaining reliable measurements despite temperature fluctuations.
3Measurement precision
If longitudinal grooves are introduced to concentrate mechanical stress, then the sensitivity is improved, but the device complexity increases
Solution Approach 1:
The longitudinal grooves segment the carrier chip surface into distinct regions, creating a pattern that concentrates stress in specific areas. This segmentation approach achieves sensitivity enhancement through a relatively simple geometric modification rather than complex additional components, balancing sensitivity improvement with acceptable device complexity.
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 design enhances sensitivity and robustness by concentrating mechanical stress between grooves and reduces temperature-induced variability through adjustable supply voltage, ensuring accurate pressure measurements across varying temperatures.
Implementation Method 1
The carrier chip has a modulus of elasticity that differs from the modulus of elasticity of the solid body. Due to these different moduli of elasticity, the mechanical stresses occur in the carrier chip. These mechanical stresses cause a change of the electrical resistance of the piezoresistive resistors or of the field effect transistors in the surface of the carrier chip
Data Source
AI summary
A pressure sensor (10) has a carrier chip (20) in and/or on which at least one sensor element (30) is integrated, the measuring signal of which depends on the mechanical stress in the carrier chip (20). The carrier chip (20) is connected on its back side in a flat and material-locking fashion to a solid body (50), the modulus of elasticity of which differs from the modulus of elasticity of the carrier chip (20). The carrier chip (20) has at least two independent and longitudinal grooves (80a, 80b) between which the sensor element (30a, 30b) is arranged. The pressure sensor has a bias voltage circuit (40) and is used in a common rail injection system.