Semiconductor Force Sensor Chip for Temperature-Stable Strain Sensing
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Solution Overview
Problem
Strain gauges attached to compliant mechanical parts face challenges in providing accurate measurements due to small signal sensing and susceptibility to temperature drift, making them unreliable for precise force detection.
Innovation Solution
A force sensor chip made of a cubic semiconductor single crystal, integrated with piezo-resistive devices arranged non-parallel or anti-parallel to each other, and a measurement circuit to measure mechanical force based on currents flowing through these devices, which are aligned to respond differently to strain along a primary direction, enhancing accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are attached to compliant mechanical parts for force measurement, then the measurement system can detect mechanical forces, but the measurement accuracy deteriorates due to small signal sensing and temperature drift
Solution Approach 1:
The patent changes the material parameter from conventional strain gauge materials to cubic semiconductor single crystal material, which exhibits significantly higher piezoresistive effect. This parameter change enables the sensor to generate larger electrical signals in response to mechanical strain, thereby improving measurement accuracy and reliability simultaneously
Solution Approach 2:
The patent employs a composite structure combining cubic semiconductor single crystal with specifically oriented crystallographic directions ({100}, {110}, or {111} planes) to create a force sensor that leverages the anisotropic piezoresistive properties of the crystal structure, achieving enhanced measurement performance
2Measurement precision
If strain gauges are used for force detection, then the system can measure mechanical forces, but temperature drift causes measurement errors
Solution Approach 1:
The patent utilizes the unique temperature characteristics of cubic semiconductor single crystal material, which has a temperature coefficient of resistance that can be controlled and compensated. By selecting specific crystal orientations and doping levels, the temperature drift is minimized, allowing accurate force measurement across varying temperature conditions
3Reliability
If conventional strain gauges are attached to mechanical parts, then force measurement is possible, but small signal sensing reduces measurement reliability
Solution Approach 1:
The patent fundamentally changes the piezoresistive coefficient parameter by using cubic semiconductor single crystal material, which provides a much larger change in electrical resistance in response to applied strain compared to conventional strain gauge materials. This results in larger measurement signals with improved signal-to-noise ratio, enhancing both reliability and precision
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 provides improved accuracy and reliability in force measurement by compensating for temperature effects and detecting delamination, ensuring precise sensing of external mechanical forces.
Implementation Method 1
a force sensor chip made of a cubic semiconductor single crystal... a first pair of piezo-resistive devices integrated in the force sensor chip... configured to respond differently to a strain along a primary strain direction
Data Source
AI summary
A sensor system includes a force sensor including a force sensor chip made of a cubic semiconductor single crystal, and a measurement circuit; and a strain body configured to undergo a body deformation in response to an external mechanical force applied to the strain body, wherein the strain body is mechanically coupled to the force sensor chip in such a way as to couple the external mechanical force to the force sensor chip to strain the force sensor chip mainly along a primary strain direction. The force sensor chip includes a pair of piezo-resistive devices integrated in the force sensor chip. The pair of piezo-resistive devices are configured to respond differently to a strain along the primary strain direction. The measurement circuit is configured to measure the external mechanical force based on one or more currents flowing through the pair of piezo-resistive devices.