MEMS Sensor Base Structure for Accurate Acceleration Under Thermal Stress
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Solution Overview
Problem
Existing sensors using MEMS structures face challenges in achieving high detection accuracy due to thermal stress caused by temperature changes, which affect the detection signal and make it difficult to obtain precise acceleration measurements.
Innovation Solution
The sensor design includes a mounting member with a free end and a fixed region, where the fixed region is secured to the mounting member while the free end is not, allowing for thermal stress to be minimized, thereby improving detection accuracy by suppressing the influence of temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the sensor base is fully fixed to the mounting member, then structural stability is improved, but thermal stress increases due to temperature changes
Solution Approach 1:
The sensor base is divided into a fixed region (second region) and a free region (first region with free end). The fixing member only secures the second region to the mounting member, leaving the first region unfixed. This segmentation allows the fixed region to provide structural stability while the free region accommodates thermal expansion and contraction, reducing thermal stress on the sensor components.
2Manufacturing precision
If the sensor base is fully fixed, then manufacturing precision is improved, but detection accuracy deteriorates due to thermal stress influence
Solution Approach 1:
The sensor base is segmented into fixed and free regions. The fixing member attaches only the second region (containing support portions and electrodes) to the mounting member with high precision, while the first region remains free to move with temperature changes. This ensures assembly precision where needed while eliminating thermal stress that would degrade detection accuracy.
Solution Approach 2:
The harmful thermal stress is extracted from the sensor base by leaving the first region unfixed. The free end of the first region allows thermal expansion and contraction without generating stress, thereby protecting the detection signal from thermal interference while maintaining precise assembly of the fixed components.
3Strength
If the entire sensor base is constrained, then structural integrity is improved, but sensitivity to acceleration deteriorates due to thermal effects
Solution Approach 1:
The sensor base is divided into a fixed second region and a free first region. The fixing member constrains only the second region to maintain structural integrity, while the free first region allows thermal movement without affecting the sensor components. This segmentation ensures that thermal effects do not interfere with acceleration detection sensitivity.
Solution Approach 2:
Different regions of the sensor base have different constraints: the second region is fixed to provide structural integrity, while the first region is free to move with temperature changes. This local differentiation in constraint quality allows the sensor to maintain both structural strength and detection sensitivity by isolating thermal effects from the sensitive acceleration measurement components.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
According to one embodiment, a sensor includes a mounting member, a sensor section, and a fixing member. The mounting member includes a first mounting portion. The sensor section includes a sensor base and a first sensor part. The sensor base includes a first region, a second region, and a first end. The first region is between the second region and the first end. The first sensor part includes a first support portion fixed to the first region, a first movable portion supported by the first support portion, and a first fixed electrode fixed to the first region. A first gap is provided between the first region and the first movable portion. The fixing member fixes the second region to the first mounting portion. The first end is a free end.