CMOS-Integrated MEMS Micro-Speaker With Electrostatic Diaphragm Actuation

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Solution Overview

Problem

Conventional speakers occupy large spaces due to their design, which is incompatible with modern consumer devices and affects other components like sensors and electronics, and they are not suitable for miniaturization.

Innovation Solution

A MEMS speaker device integrated with a CMOS device, utilizing a movable diaphragm made of silicon or graphene, actuator devices, and a housing that generates sound pressure signals through electrostatic actuation, allowing for miniaturization without performance loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional speaker technology is used, then speaker performance is maintained, but device size increases and compatibility with modern consumer devices decreases

Engineering Contradiction:

Improvespeaker sizeVSAvoidspeaker performance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent replaces the conventional electromagnetic actuation system with an electrostatic actuation system. The electrostatic speaker uses electrostatic force between charged surfaces to drive the diaphragm, eliminating the need for permanent magnets, voice coils, and complex mechanical assemblies. This substitution enables significant miniaturization while maintaining acoustic performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent integrates the speaker diaphragm, actuator, and housing into a single monolithic structure. The diaphragm is formed as an integral part of the housing, with the electrostatic actuator embedded within the same component. This merging of functions reduces the overall speaker size and eliminates the need for separate electromagnetic components.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of manufacture

If conventional speaker design is used, then acoustic output is achieved, but integration with CMOS processing and PCB technology becomes impossible

Engineering Contradiction:

Improvemanufacturing compatibilityVSAvoidspeaker structure

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The electrostatic speaker design serves multiple functions within a single structure: the diaphragm acts as both the acoustic radiating surface and the movable electrode, the housing provides both structural support and the stationary electrode, and the same structure enables both acoustic output and electrostatic actuation. This multi-functionality simplifies manufacturing and enables integration with standard CMOS and PCB processes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If conventional speakers with magnets are used, then electromagnetic actuation works, but interference with sensors and other electronics occurs

Engineering Contradiction:

Improvemagnetic interferenceVSAvoidactuation force

Core Design Contradiction:

Object-affected harmful factorsVSPower

Solution Approach 1:

The patent eliminates permanent magnets and electromagnetic fields by using electrostatic actuation. The electrostatic speaker generates acoustic force through electrostatic attraction and repulsion between charged surfaces, completely removing the source of magnetic interference that plagues conventional speakers and their impact on nearby sensors and electronics.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Volume of moving object

If speaker miniaturization is pursued, then device integration improves, but conventional electromagnetic actuation becomes ineffective

Engineering Contradiction:

Improvespeaker volumeVSAvoidactuation force

Core Design Contradiction:

Volume of moving objectVSForce

Solution Approach 1:

The patent replaces electromagnetic actuation with electrostatic actuation, which generates force through electrostatic pressure between charged surfaces. This electrostatic force scales effectively with miniaturization, allowing the same actuation mechanism to work in both large and small speakers, unlike electromagnetic systems where force generation becomes problematic at small scales.

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 MEMS speaker device reduces size and profile height while maintaining performance, integrating CMOS audio processing to miniaturize audio components in devices like earbuds and smartphones, and can be manufactured using conventional semiconductor and MEMS processes.

Implementation Method 1

an actuator device configured to electrostatically move the movable diaphragm device

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS20250358572A1Integrated MEMS Electrostatic Micro-Speaker Device and System

Publication Date: 2025.11.20 VIBRANT MICROSYSTEMS INC

AI summary

In an example, the present invention provides a micro-speaker device. The device has a movable diaphragm device comprising a thickness of silicon or graphene material which has a first surface and a second surface opposite of the first surface and sensor to track position of the diaphragm. The device has a housing enclosing the movable diaphragm device, the electrode device and an encapsulation device. The electrode device can be part of a CMOS device with electronics integrated on to the device that converts input audio signal in to signal that electrostatically actuates the micro-speaker from one or more surfaces.