Strain Decoupled Sensor With Segmented Spacer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Sensors with components of different materials and coefficients of thermal expansion experience inaccuracies due to thermally induced stresses, which affect their operation, particularly in micro-electromechanical systems like accelerometers and gyroscopes.
Innovation Solution
A sensor design featuring a substrate and sensor element of dissimilar materials, with a small spacer anchoring the sensor element to the substrate, reducing the area of contact and thus minimizing thermally induced stresses by spacing them apart, typically by 30 μm or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the sensor element is rigidly interconnected to the substrate using multiple bonding areas, then the mechanical stability and structural integrity are improved, but thermally induced stresses increase due to differential thermal expansion between dissimilar materials
Solution Approach 1:
The bonding interface is segmented from multiple bonding areas into a single localized spacer connection. This segmentation isolates the thermal expansion differential to one small point rather than distributing it across multiple bonding areas, reducing the overall thermally induced stresses while maintaining mechanical stability through the anchored connection.
Solution Approach 2:
A spacer is introduced as an intermediary element between the sensor element and substrate. This spacer serves as a mechanical mediator that anchors the sensor element while accommodating thermal expansion differences, preventing direct rigid bonding that would transmit thermal stresses across the entire interface.
2Strength
If the area of contact between sensor element and substrate is increased, then the mechanical anchoring strength is improved, but the impact of thermally induced stresses on sensor operation increases
Solution Approach 1:
The contact area is segmented from a large continuous interface into a single small spacer connection. This concentrated anchoring point provides sufficient mechanical strength to hold the sensor element while minimizing the area over which thermal expansion differential can generate damaging stresses that would affect sensor accuracy.
Solution Approach 2:
The anchoring function is localized to a single small spacer region rather than distributed across the entire sensor element surface. This local quality approach concentrates the mechanical bonding where needed for strength while leaving the rest of the sensor element free from thermally induced stresses that would compromise operational reliability.
3Measurement precision
If dissimilar materials with different coefficients of thermal expansion are used for substrate and sensor element, then the functional performance and sensitivity are improved, but thermally induced stresses are generated during temperature changes
Solution Approach 1:
The spacer acts as an intermediary that enables the use of dissimilar materials with different thermal expansion coefficients. It provides the mechanical connection needed for structural integrity while isolating the thermal expansion differential to a small localized area, preventing the generation of widespread thermally induced stresses that would otherwise compromise sensor accuracy.
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
This design significantly reduces the impact of thermally induced stresses on the sensor's operation, enhancing its accuracy and sensitivity with minimal additional manufacturing complexity.
Implementation Method 1
the substrate and sensor element being of dissimilar materials and having different coefficients of thermal expansion
Data Source
AI summary
A sensor comprises a substrate 16 and a sensor element 20 anchored to the substrate 16, the substrate 16 and sensor element 20 being of dissimilar materials and having different coefficients of thermal expansion, the sensor element 20 and substrate 16 each having a generally planar face arranged substantially parallel to one another, the sensor further comprising a spacer 26, the spacer 26 being located so as to space at least part of the sensor element 20 from at least part of the substrate 16, wherein the spacer 26 is of considerably smaller area than the area of the smaller of face of the substrate 16 and that of the sensor element 20.