MEMS Flexure Damping With Localized Viscoelastic Fluid

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Solution Overview

Problem

MEMS devices face challenges in controlling mechanical damping, leading to high susceptibility to shock and vibrations due to low damping losses in standard air environments, which complicates actuation and resonance control.

Innovation Solution

Incorporating viscoelastic fluid confinement structures on the substrate and suspended elements to confine viscoelastic fluid in specific gaps between the fixed and suspended parts, using sharp edges, winglets, and reservoirs to enhance damping without affecting the stiffness of the MEMS device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If MEMS devices operate in standard air environment, then device simplicity is maintained, but damping losses are low leading to high susceptibility to shock and vibrations

Engineering Contradiction:

Improvesusceptibility to shock and vibrationsVSAvoiddamping losses

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The patent introduces a viscoelastic fluid as an intermediary substance between the suspended element and the substrate. This fluid mediates the mechanical interaction by providing viscous damping forces that dissipate vibration energy, thereby reducing the harmful effects of shock and vibrations without requiring fundamental changes to the MEMS device structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical parameter of the operating environment by replacing air with a viscoelastic fluid. This parameter change transforms the damping characteristics from low (air) to high (viscoelastic fluid), enabling effective vibration suppression while maintaining the device's operational functionality.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If viscoelastic fluid is added to increase damping, then damping performance is improved, but device complexity increases due to fluid confinement structures

Engineering Contradiction:

Improvedamping lossesVSAvoidfluid confinement structures

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent employs thin film membranes as flexible containment structures to confine the viscoelastic fluid. These thin films provide fluid containment while maintaining mechanical flexibility and minimal interference with the suspended element's motion, thereby achieving high damping performance with minimal added complexity.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The substrate serves multiple functions: it provides structural support, acts as a reservoir for the viscoelastic fluid, and forms part of the fluid confinement structure. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Loss of energy

If damping structures are added to confine viscoelastic fluid, then damping is enhanced, but manufacturing complexity increases

Engineering Contradiction:

Improvedamping lossesVSAvoidmanufacturing complexity

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent divides the fluid confinement into multiple discrete structures such as separate reservoirs, channels, and barrier layers. This segmentation allows each component to be fabricated using standard MEMS processing steps, making the overall manufacturing process more manageable and compatible with existing fabrication capabilities.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces complex mechanical fluid confinement structures with electrostatic or surface tension-based containment mechanisms. This substitution eliminates the need for intricate mechanical seals and moving parts, thereby simplifying the manufacturing process while maintaining effective fluid confinement.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 significantly increases damping in MEMS devices, providing nearly critical underdamping or critical damping, thereby reducing susceptibility to shock and vibrations and improving mechanical control.

Implementation Method 1

MEMS device with improved dynamic mechanical performance through damping by localized viscoelastic medium

Methodology Applied

Scientific EffectViscoelastic damping: Viscoelasticity

Data Source

PatentUS11772959B2MEMS device with improved dynamic mechanical performance through damping by localized viscoelastic medium

Publication Date: 2023.10.03 MIRRORCLE TECH

AI summary

MEMS devices include a suspended element connected to a fixed part of a substrate by one or more flexures, wherein the one or more flexures are configured to permit movement of the suspended element relative to a fixed part of the substrate. An actuator coupled to the suspended element and a damping structure coupled to the suspended element extends into a gap between the suspended element and the fixed part of the substrate. One or more fluid confinement structures are configured to permit movement of the damping structure within a limited portion of the gap and to confine a viscoelastic fluid to the limited portion of the gap.