Asymmetric Single-Sided Mounting for Strain Sensor Thermal Isotropy
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Solution Overview
Problem
Devices for measuring mechanical quantities in objects with large thermal expansion coefficients, such as plastic resin, face precision issues due to differences in thermal expansion between the object and the base plate metal body, leading to isotropy loss and measurement inaccuracies.
Innovation Solution
A device with a metal body and semiconductor strain sensors mounted on it, where only one side of the metal body is fixed to the object, allowing for precise measurement of deformation or strain quantities by minimizing the influence of thermal expansion coefficient differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If two fastened portions on both sides of the semiconductor strain sensor chip are used to connect the base plate to the object, then the connection strength is improved, but the base plate loses isotropy in expansion and measurement precision deteriorates due to thermal strain influence
Solution Approach 1:
The patent changes the symmetric two-sided fastening structure to an asymmetric single-sided fastening structure. The semiconductor strain sensor chip is fastened to the base plate at only one location, which maintains the isotropy of the base plate during thermal expansion and prevents the generation of thermal strain that would affect measurement precision.
Solution Approach 2:
The patent extracts one of the two fastened portions from the connection structure, retaining only a single fastened portion. This reduction eliminates the lateral drawing effect on both sides that caused loss of isotropy and thermal strain influence, while still providing sufficient connection strength through the remaining single fastening point.
2Adaptability or versatility
If the object to be measured has a thermal expansion coefficient larger than that of the metal base plate, then the device can measure deformation in plastic resin objects, but thermal expansion differences cause isotropy loss and measurement inaccuracies
Solution Approach 1:
The patent introduces a single fastened portion as an intermediary connection that allows the metal base plate to expand isotropically without being constrained by the plastic resin object's larger thermal expansion coefficient. This single connection point acts as a mediator that prevents the transmission of thermal strain from the object to the measurement chip.
3Stability of the object's composition
If two fastened portions are used on both sides of the semiconductor strain sensor chip, then the structural stability is improved, but the fastened portions are drawn laterally by thermal expansion causing loss of isotropy
Solution Approach 1:
The patent applies asymmetry by using a single fastened portion instead of symmetric two-sided fastening. This asymmetric configuration allows the base plate to maintain its isotropic expansion characteristics during thermal cycling, as there is only one connection point to constrain the expansion rather than two points that would create lateral drawing and distort the expansion pattern.
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 solution effectively reduces the impact of thermal strain on measurement precision, enabling accurate detection of mechanical quantities in objects with significant thermal expansion, maintaining isotropy and improving measurement reliability.
Implementation Method 1
a strain detection unit using not the metal thin film but semiconductor piezoresistance formed by doping impurities in a semiconductor such as silicon
Implementation Method 2
when the object to be measured such as a plastic resin has a thermal expansion coefficient larger than that of the base plate metal body by approximately one digit
Data Source
AI summary
A device for measuring mechanical quantity is provided which reduces the influence of a difference in thermal expansion coefficient between an object to be measured and a base plate metal body, and precisely measures a mechanical quantity such as deformation quantity or strain quantity caused in the object to be measured. The device includes a semiconductor strain sensor module for measuring deformation quantity of the object to be measured, and the module includes a metal body, and a semiconductor strain sensor mounted on the metal body to detect strain of the metal body. The object to be measured is made of a material having a thermal expansion coefficient larger than that of the metal body. Further, the metal body mounted with the semiconductor strain sensor has a structure configured to be fixed to the object to be measured.