# US 11,189,258 B2 · Nanovoided polymer for tunable acoustic damping > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,189,258 B2 - Document ID: US11189258B2 - Status: Granted - Kind: B2 - Application number: 16/735,454 - Filed: 2020-01-06 - Published: 2020-07-16 - Granted: 2021-11-30 - Earliest claimed: 2019-01-10 - Assignees: Facebook Technologies, LLC - Applicants: Facebook Technologies, LLC - Inventors: Renate Eva Klementine Landig; Kenneth Diest; Andrew John Ouderkirk - Web page: https://patentgrep.com/patent/US11189258B2 ## CPC - B06B 1/0688: {with foil-type piezoelectric elements, e.g. PVDF} - G10K 11/165: Particles in a matrix - B06B 1/0292: {Electrostatic transducers, e.g. electret-type} - B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals - C03C 17/30: with silicon-containing compounds - C03C 17/32: with synthetic or natural resins (C03C17/30 takes precedence) - G01H 9/00: Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means - G01H 11/06: by electric means - G02F 1/15165: {Polymers} - G10K 11/162: Selection of materials - G10K 11/178: by electro-acoustically regenerating the original acoustic waves in anti-phase - G10K 11/1785: {Methods, e.g. algorithms; Devices (G10K11/1781, G10K11/1783 take precedence)} - G10K 11/17881: {the reference signal being an acoustic signal, e.g. recorded with a microphone} - B06B 1/0622: {on one surface} - B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites - G10K 2210/118: Panels, e.g. active sound-absorption panels or noise barriers - G10K 2210/3212: Actuator details, e.g. composition or microstructure - G10K 2210/3217: Collocated sensor and cancelling actuator, e.g. "virtual earth" designs - G10K 2210/3226: Sensor details, e.g. for producing a reference or error signal - B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R) - G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS - G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract An acoustic element includes a nanovoided polymer layer having a first nanovoid topology in an unactuated state and a second nanovoid topology different than the first nanovoid topology in an actuated state. Capacitive actuation of the nanovoided polymer layer, for instance, can be used to reversibly control the size and shape of the nanovoids within the polymer layer and hence tune its sound damping characteristics or sound transduction behavior, e.g., during operation of the acoustic element. An acoustic element may be configured for passive or active sound attenuation. Various other apparatuses, systems, materials, and methods are also disclosed. ## Claims ### Claim 1 An acoustic element comprising an electroactive polymer comprising a nanovoided polymer layer, wherein: the nanovoided polymer layer comprises a first nanovoid topology in a first state and a second nanovoid topology different from the first nanovoid topology in a second state; applying a voltage across the electroactive polymer causes a reversible conformation change between the first nanovoid topology and the second nanovoid topology; and the first nanovoid topology attenuates sound waves to a degree that differs from a degree to which the second nanovoid topology attenuates sound waves. ### Claim 2 (depends on 1) The acoustic element of claim 1, wherein the first state comprises an unactuated state and the second state comprises an actuated state. ### Claim 3 (depends on 1) The acoustic element of claim 1, wherein the nanovoided polymer layer comprises a periodic distribution of nanovoids. ### Claim 4 (depends on 1) The acoustic element of claim 1, wherein nanovoids within the nanovoided polymer layer comprise a gas selected from the group consisting of air, nitrogen, oxygen, argon, sulfur hexafluoride, and an organofluoride. ### Claim 5 (depends on 1) An acoustic insulator comprising the acoustic element of claim 1. ### Claim 6 (depends on 5) The acoustic insulator of claim 5, wherein the acoustic element is configured to emit sound waves in response to sounds waves incident on the acoustic element. ### Claim 7 (depends on 6) The acoustic insulator of claim 6, wherein the emitted sound waves and the incident sound waves comprise an out-of-phase relationship. ### Claim 8 (depends on 1) An acoustic transducer comprising the acoustic element of claim 1. ### Claim 9 (depends on 8) The acoustic transducer of claim 8, wherein sound waves are produced by applying an AC voltage across the nanovoided polymer. ### Claim 10 (depends on 8) The acoustic transducer of claim 8, wherein sound waves incident on a layer of the nanovoided polymer induce a change in capacitance in the nanovoided polymer layer. ### Claim 11 An acoustic element, comprising: a primary electrode; a secondary electrode overlapping at least a portion of the primary electrode; and a nanovoided polymer layer disposed between and abutting the primary electrode and the secondary electrode, wherein: the nanovoided polymer layer has a first nanovoid topology when a first voltage is applied between the primary electrode and the secondary electrode, the nanovoided polymer layer has a second nanovoid topology different from the first nanovoid topology when a second voltage different from the first voltage is applied between the primary electrode and the secondary electrode; and the first nanovoid topology attenuates sound waves to a degree that differs from a degree to which the second nanovoid topology attenuates sound waves. ### Claim 12 (depends on 11) The acoustic element of claim 11, wherein sound waves are produced by applying an AC voltage across the nanovoided polymer layer. ### Claim 13 (depends on 11) The acoustic element of claim 11, wherein sound waves incident on the nanovoided polymer layer induce a change in capacitance in the nanovoided polymer layer. ### Claim 14 (depends on 11) The acoustic element of claim 11, wherein the nanovoided polymer layer has a first sound attenuation coefficient when the first voltage is applied between the primary electrode and the secondary electrode and a second sound attenuation coefficient different than the first sound attenuation coefficient when the second voltage is applied between the primary electrode and the secondary electrode. ### Claim 15 (depends on 11) The acoustic element of claim 11, characterized by an optical transparency within the visible spectrum of at least approximately 50%. ### Claim 16 A device comprising an array of acoustic elements, where the acoustic elements comprise at least one of: (i) a plurality of nanovoided polymer-containing acoustic insulators, and (ii) a plurality of nanovoided polymer-containing acoustic transducers; wherein at least one of the acoustic elements comprises an electroactive polymer comprising a nanovoided polymer layer, wherein: the nanovoided polymer layer comprises a first nanovoid topology in a first state and a second nanovoid topology different from the first nanovoid topology in a second state; applying a voltage across the electroactive polymer causes a reversible conformation change between the first nanovoid topology and the second nanovoid topology; and the first nanovoid topology attenuates sound waves to a degree that differs from a degree to which the second nanovoid topology attenuates sound waves. ### Claim 17 (depends on 16) The device of claim 16, wherein a spacing between each acoustic element is from approximately 0.5 μm to approximately 15 cm. ### Claim 18 (depends on 16) The device of claim 16, wherein the array of acoustic elements is disposed on a non-planar substrate. ### Claim 19 (depends on 16) The device of claim 16, wherein the array of acoustic elements is disposed on a flexible substrate. ### Claim 20 (depends on 16) The device of claim 16, wherein each acoustic element within the array comprises an electrode pair.