MEMS Active Element With Porous Core Layer

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Solution Overview

Problem

Existing MicroElectroMechanical Systems (MEMS) face inefficiencies in energy usage and sensitivity due to the rigidity of the retention layer, which affects the active element's ability to bend effectively in actuator and sensor modes, leading to energy loss and reduced performance.

Innovation Solution

The MEMS design incorporates a core layer with recesses and pillars to position the neutral axis within the core or retention layer, providing anisotropic rigidity and minimizing stress for bending, allowing for thicker active elements without compromising energy efficiency or sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the retention layer has greater thickness and rigidity to provide sufficient structural support, then the structural stability is improved, but the energy efficiency and sensitivity of the active element deteriorate due to increased stress during bending

Engineering Contradiction:

Improvestructural stabilityVSAvoidenergy efficiency

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The core layer is designed with a porous structure containing multiple voids or recesses. This porous configuration reduces the overall rigidity of the core layer while maintaining its structural support function, thereby decreasing the stress experienced by the active layer during bending operations and improving energy efficiency without compromising structural stability

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The active element employs a composite structure consisting of multiple layers (active layer, core layer, and retention layer) with different mechanical properties. The core layer acts as a transition zone with intermediate rigidity between the soft active layer and the rigid retention layer, optimizing the stress distribution and reducing energy loss during bending

Inventive Principle:

Principle #40Composite materials

2Strength

If the active element is thickened to meet certain application requirements (e.g., micropumps, speakers), then the structural strength is improved, but the energy efficiency and sensitivity deteriorate

Engineering Contradiction:

Improvestructural strengthVSAvoidenergy efficiency

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The core layer exhibits spatially varying rigidity through its porous structure, with different regions having different densities and mechanical properties. This allows the active element to achieve sufficient overall strength while maintaining low stress in the active layer region, thereby preserving energy efficiency even with increased thickness

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The core layer is segmented into multiple regions with voids or recesses distributed throughout its volume. This segmentation creates a lightweight structure with reduced rigidity that minimizes stress on the active layer during bending, enabling thicker active elements to maintain energy efficiency

Inventive Principle:

Principle #1Segmentation

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 enhances energy efficiency and sensitivity by reducing stress and maintaining performance, enabling thicker active elements while maintaining or improving energy efficiency and sensitivity compared to prior art MEMS.

Implementation Method 1

The active layer comprises a material that is capable of undergoing a deformation and deforming the beam or membrane in a direction perpendicular to the plane defined by the front face as soon as an electric signal is imposed thereon

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the active element of a MEMS operating in sensor mode will undergo a deformation under the action of an outside stress so that said active element produces an electric signal representative of said outside stress

Methodology Applied

Scientific EffectConverse piezoelectric effect: Converse Piezoelectric Effect

Data Source

PatentUS11716907B2Electromechanical microsystem comprising an active element having a structured core layer

Publication Date: 2023.08.01 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A MicroElectroMechanical System is provided, with an active element configured to carry out an electromechanical function, the active element including, from an upper face to a lower face substantially parallel to the upper face, an active layer, a core layer, and a retention layer, the active layer being configured to, under the effect of a first electric signal, go into a mechanically stressed state, configured to generate a bending of the active element in a direction perpendicular to a front face thereof, and vice versa, the active layer, the core layer, and the retention layer being arranged so that a neutral axis, associated with an elongation of zero in a case of bending of the active element, is located in a volume of one or the other of the core layer and of the retention layer, and the core layer further includes at least 20% recesses in its volume.