Flexible Screen MEMS Sound Transducer for Acoustic Sealing

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Solution Overview

Problem

Existing MEMS loudspeaker concepts face challenges in achieving a balance between acoustic properties, manufacturability, miniaturization, and complexity, often requiring complex and expensive manufacturing methods with insufficient performance characteristics.

Innovation Solution

The development of an MEMS sound transducer featuring a deflectable bending transducer element clamped on one side with a flexible screen structure that extends along its edge, allowing for bending and torsion, which prevents acoustic short-circuiting and reduces stiffness, enabling higher deflections and energy efficiency while being cost-effective and producible using conventional silicon technology.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fixed flow screens are used to prevent acoustic short-circuiting, then acoustic performance is improved, but the bending transducer becomes stiffer and deflection capability decreases

Engineering Contradiction:

Improveacoustic performanceVSAvoidstiffness

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The screen structure is made flexible instead of fixed, allowing it to dynamically adapt to the bending transducer's movement. The screen can deflect together with the bending transducer, maintaining acoustic sealing while accommodating large deflections without increasing stiffness.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

A flexible screen made of thin film material is used instead of rigid structures. The thin film can bend and deform with the bending transducer, preventing acoustic short-circuiting while maintaining flexibility and not restricting deflection capability.

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If hybrid manufacturing methods are used to achieve good performance characteristics, then acoustic performance is improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improveperformance characteristicsVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The screen structure is merged with the bending transducer as a single integrated component made from the same substrate material. This eliminates the need for hybrid assembly of separate membrane elements, reducing manufacturing complexity while maintaining good performance characteristics.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The substrate serves multiple functions: it forms both the bending transducer structure and the screen structure. This multi-functionality eliminates the need for additional materials and hybrid manufacturing processes, simplifying production while achieving both acoustic sealing and mechanical flexibility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If closed membrane structures are used, then acoustic sealing is improved, but energy consumption increases due to deformation requirements

Engineering Contradiction:

Improveacoustic sealingVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of using a fully closed membrane structure, the invention uses a screen structure with openings that provides sufficient acoustic sealing through the screen effect. This partial action approach reduces the energy required for deformation while maintaining effective acoustic sealing.

Inventive Principle:

Principle #16Partial or excessive action

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 approach results in improved performance with increased sound pressure levels, broader frequency range, and cost savings by eliminating the need for hybrid assembly, enabling more accurate sound generation and detection, and allowing for integration of multiple sound transducers on a single chip.

Implementation Method 1

The deflectable bending transducer element is configured to be subjected to bending along a bending line and/or torsion along a torsion axis as a result of a force in order to be deflected as a result of the bending

Methodology Applied

Scientific EffectBending:

Implementation Method 2

The deflectable bending transducer element is configured to be subjected to bending along a bending line and/or torsion along a torsion axis as a result of a force

Methodology Applied

Scientific EffectTorsion:

Implementation Method 3

Small gap widths of a few micrometers and optional flow screens prevent an acoustic short circuit

Methodology Applied

Scientific EffectAcoustic short-circuit prevention:

Data Source

PatentUS20240340597A1MEMS sound transducer

Publication Date: 2024.10.10 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

An MEMS sound transducer having: a deflectable bending transducer element which is clamped on at least one side relative to a surrounding structure, the bending transducer element having a free end on at least one side, which is separated from the surrounding structure by a gap, the deflectable bending transducer element being configured to be subjected to bending along a bending line and/or torsion along a torsion axis as a result of a force in order to be deflected as a result of the bending, the deflectable bending transducer element having at least one screen structure which projects vertically from one of the main directions of extension of the bending transducer element and is implemented to be flexible at least along the bending line and/or along the torsion axis.