MEMS Yaw Rate Sensor Shock Protection via Resilient Stop Elements
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Solution Overview
Problem
Conventional MEMS yaw rate sensors are prone to damage and particle formation under shock loads due to the collision of movable structures with fixed electrodes, leading to mechanical failure.
Innovation Solution
Incorporating robust stop elements in the first functional layer, which can absorb energy through a resilient design and transition to a harder stop before impact, reducing torque and preventing structural breakage, allowing for a soft and hard stop mechanism to protect the sensor mass from shock damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the movable structure is mounted softly to allow large deflection for high sensitivity, then the capacitive signal is strong, but the movable structure collides with fixed electrodes under shock load causing damage
Solution Approach 1:
A resilient stop element is positioned between the movable structure and the fixed electrode to provide cushioning before collision occurs. The stop element absorbs shock energy through elastic deformation, preventing direct impact between the movable structure and fixed electrode, thus resolving the contradiction between soft mounting for sensitivity and shock robustness.
2Measurement precision
If the distance between movable structure and fixed electrodes is kept short to achieve strong capacitive signal, then sensitivity is high, but the impact force during shock load increases causing structural failure
Solution Approach 1:
The resilient stop element acts as an intermediary component positioned between the movable structure and the fixed electrode. It provides mechanical cushioning while allowing the electrode spacing to remain small for high capacitive signal strength, thus protecting the structural integrity without compromising measurement precision.
3Power
If the functional layer thickness is increased to allow large mass for strong Coriolis force, then measurement capability is improved, but the torque on attachment during shock load increases causing breakage
Solution Approach 1:
The resilient stop element provides beforehand cushioning that reduces the shock torque transmitted to the attachment. This allows the functional layer to be made thicker for stronger Coriolis force and better measurement capability, while the stop element protects the attachment from excessive torque during shock events.
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 enhances the shock resistance of MEMS yaw rate sensors, preventing damage and particle formation under high loads while maintaining sensitivity by dissipating energy slowly and avoiding abrupt braking, thus ensuring the sensor's integrity and performance.
Implementation Method 1
the fixed stop element and/or the movable stop element is resilient in the first direction by means of a spring element
Data Source
AI summary
A micromechanical device having a substrate with a main extension plane, a thin first functional layer over the substrate, and a thick second functional layer over the first functional layer. A fixed functional element and a movable functional element are formed in the second functional layer, The movable functional element is able to deflect in a first direction parallel to the main extension plane. The micromechanical device has a fixed stop element in the first functional layer, the movable functional element is also formed in the first functional layer and has a movable stop element there. The movable stop element can be applied to the fixed stop element when the movable functional element is deflected in the first direction.