MEMS Protrusion Stoppers for Shock Absorption
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Solution Overview
Problem
Microelectromechanical Systems (MEMS) devices face challenges in withstanding and responding to various forces and shocks without sustaining damage, as existing designs often lack effective mechanisms to absorb and distribute forces, leading to potential stiction and structural damage.
Innovation Solution
The MEMS device incorporates a suspended movable structure and a resilient structure with strategically positioned protrusions acting as soft and hard stoppers, where the first protrusion, coupled to the resilient structure, absorbs initial shocks and the second protrusion, coupled to the proof mass, provides additional support, preventing stiction and structural damage by controlling contact points and areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a suspended movable structure is used in MEMS device, then the device can sense physical conditions effectively, but the device becomes vulnerable to damage from forces and shocks
Solution Approach 1:
The patent applies beforehand cushioning by incorporating a resilient structure with a first protrusion that acts as a soft stopper before the proof mass can contact the stationary structure. This cushioning element is positioned in advance to absorb shock and prevent direct impact, thereby protecting the MEMS device from damage during high-g events while maintaining the suspended movable structure's sensing capability
2Reliability
If the movable structure is allowed to move freely to sense acceleration, then sensing accuracy is improved, but stiction and structural damage occur during high-g events
Solution Approach 1:
The patent applies segmentation by dividing the stopping mechanism into two distinct segments: a first protrusion (soft stopper) coupled to the resilient structure for initial shock absorption, and a second protrusion (hard stopper) on the stationary structure for final support. This segmented approach prevents stiction by controlling contact points and areas, allowing the proof mass to move freely during normal operation while providing structured support during high-g events
Solution Approach 2:
The resilient structure with the first protrusion acts as an intermediary between the proof mass and the stationary structure. This intermediary element absorbs shock and controls the interaction between moving and stationary components, preventing direct contact and stiction while maintaining the ability to sense acceleration accurately
3Reliability
If protrusions are added to prevent damage and stiction, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies merging by integrating the first protrusion directly into the resilient structure and the second protrusion into the proof mass, rather than adding them as separate components. This merging approach reduces device complexity by combining protective elements with existing structural components, while still providing the necessary shock absorption and stiction prevention functionality
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 configuration effectively absorbs and distributes forces, preventing damage to the MEMS device by using the first protrusion as a soft stopper for initial shock absorption and the second protrusion as a hard stopper for higher forces, minimizing stiction and structural contact, thereby enhancing the device's durability and operational reliability.
Implementation Method 1
a resilient structure over the substrate. The resilient structure has a second edge facing and spaced away from the first edge of the stationary structure
Implementation Method 2
The first protrusion, coupled to the resilient structure, absorbs initial shocks
Implementation Method 3
the second protrusion, coupled to the proof mass, provides additional support, preventing stiction and structural damage by controlling contact points and areas
Data Source
AI summary
A device includes a stationary structure, a spring and a proof mass. The stationary structure has a first portion and a second portion. The spring is over a substrate. The spring has a first protrusion protruded from an edge and extended toward the first portion of the stationary structure. The proof mass is over the substrate and supported by the sparing. The proof mass has a second protrusion protruded from an edge and extended toward the second portion of the stationary structure. A first gap between the first protrusion and the first portion is less than a second gap between the second protrusion and the second portion.