Holeless Microphone Using Acoustic Metamaterial Casing

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Solution Overview

Problem

Traditional microphones in mobile devices require acoustic holes for effective sound wave transmission, which compromises the device's water resistance, sleek design, and screen-to-body ratio.

Innovation Solution

A solid-state microphone apparatus using a composite material with conductive particles, such as graphene, that alters internal impedance in response to acoustic waves, allowing for effective sound detection without the need for airflow paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If acoustic holes are provided in the mobile device for microphone function, then audio recording capability is improved, but water resistance and device strength deteriorate

Engineering Contradiction:

Improveaudio recording capabilityVSAvoidwater resistance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent extracts the acoustic wave transmission function from the traditional hole-based approach and relocates it to the device casing itself. The casing is designed with specific acoustic properties (acoustic metamaterial structure) that enable sound wave transmission without requiring physical holes, thus eliminating the contradiction between audio recording capability and water resistance.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the acoustic parameters of the casing material by incorporating acoustic metamaterial structures that allow selective transmission of acoustic waves while maintaining physical integrity. This parameter change enables the casing to simultaneously achieve sound transmission (improving audio recording) and water resistance (maintaining reliability).

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If acoustic holes are provided in the mobile device for microphone function, then sound wave transmission is improved, but device aesthetics and screen-to-body ratio deteriorate

Engineering Contradiction:

Improvesound wave transmissionVSAvoiddevice aesthetics

Core Design Contradiction:

Ease of operationVSShape

Solution Approach 1:

The patent removes the need for visible acoustic holes from the device exterior by integrating the acoustic transmission function into the casing material itself. This extraction of the hole requirement maintains the sleek, continuous surface of the device (improving aesthetics) while preserving sound wave transmission capability through the acoustic metamaterial properties of the casing.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The casing is designed to serve multiple functions simultaneously: structural support, water resistance, and acoustic wave transmission. By making the casing itself acoustically transparent through metamaterial design, the device maintains its aesthetic appearance without compromise to sound transmission functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Strength

If acoustic holes are reduced in size for holeless design, then device strength and water resistance are improved, but transmission losses increase and signal-to-noise ratio deteriorates

Engineering Contradiction:

Improvedevice strengthVSAvoidtransmission losses

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The patent fundamentally changes the acoustic transmission parameter from hole-based physical openings to material-based acoustic metamaterial properties. This parameter change allows the casing to transmit acoustic waves efficiently without energy loss, eliminating the trade-off between device strength and transmission losses. The acoustic metamaterial structure enables high transmission efficiency while maintaining full device integrity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical hole-based acoustic transmission system with an acoustic metamaterial-based system. Instead of relying on physical openings (mechanical structure) for sound transmission, the solution uses the intrinsic acoustic properties of the metamaterial casing, which eliminates transmission losses and maintains device strength simultaneously.

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

Enables high-sensitivity audio recordings in holeless mobile devices, maintaining water resistance and enhancing device aesthetics, while reducing transmission losses and improving signal-to-noise ratio.

Implementation Method 1

the composite material configured to alter an internal impedance based on a surface disturbance transmitted by an acoustic wave

Methodology Applied

Scientific EffectImpedance modulation by acoustic waves:

Implementation Method 2

The composite material may further comprise a viscoelastic polymer

Methodology Applied

Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 3

The conductive particles may comprise at least one of: graphene; silver; and copper

Methodology Applied

Scientific EffectElectrical conductivity change with strain:

Data Source

PatentUS12342113B2Microphone apparatus

Publication Date: 2025.06.24 NOKIA TECHNOLOGIES OY

AI summary

A microphone apparatus including: a casing; a composite material located within the casing, the composite material including at least in part conductive particles, the composite material configured to alter an internal impedance based on a surface disturbance transmitted by an acoustic wave, and wherein the microphone apparatus is configured to be coupled to a surface that transmitted the acoustic wave.