This disclosure provides systems, methods, and apparatus associated with an electrostatically driven graphene speaker. In one aspect, a device includes a graphene membrane, a first frame on a first side of the graphene membrane, and a second frame on a second side of the graphene membrane. The first frame and the second frame both include substantially circular open regions that define a substantially circular portion of the graphene membrane. A first electrode is proximate the first side of the circular portion of the graphene membrane. A second electrode proximate the second side of the circular portion of the graphene membrane.

A transducer includes an acoustic reflector, an acoustic coupler and one or more thermoacoustic frames. The acoustic coupler is disposed proximate to an output of the transducer and each of the thermoacoustic frames is disposed between the acoustic reflector and the acoustic coupler. The thermoacoustic frames, the acoustic reflector and the acoustic coupler form a resonator with each of the thermoacoustic frames configured to emit a broadband acoustic signal in response to receiving electrical energy. Additionally, the resonator is configured to emit a narrowband acoustic signal at the transducer output in response to receiving the broadband acoustic signal. A method includes adjusting a frequency of the narrowband acoustic signal by controlling a spacing between the thermoacoustic frames and one or more components of the resonator. Thermoacoustic device embodiments capable of resonant emission of intense ultrasound radiation generated by sheets of multi-walled carbon nanotubes (MWNT) are also disclosed.

An MEMS has a substrate and a cavity arranged in the substrate. A movable element is arranged in the cavity, configured to interact with a fluid arranged in the cavity, wherein a movement of the fluid and a movement of the movable element are causally related. A first opening which connects the cavity to an environment of the substrate causes a first phase offset of a first periodic oscillation which is causally related to the movement of the movable element when passing through the first opening. A second opening which connects the cavity to the environment of the substrate causes a second phase offset, different from the first phase offset, of a second periodic oscillation which is causally related to the movement of the movable element when passing through the second opening.

A pressure wave generating element that includes a support and a fiber layer on the support and constructed to generate heat by energization. The fiber layer is in the form of a fiber membrane having an average pore diameter in a range of 0.1 to 1.0 m, and the fiber layer includes one or more fibers having a surface at least partly provided with a metal coating.

This disclosure provides systems, methods, and apparatus associated with an electrostatically driven graphene speaker. In one aspect, a device includes a graphene membrane, a first frame on a first side of the graphene membrane, and a second frame on a second side of the graphene membrane. The first frame and the second frame both include substantially circular open regions that define a substantially circular portion of the graphene membrane. A first electrode is proximate the first side of the circular portion of the graphene membrane. A second electrode proximate the second side of the circular portion of the graphene membrane.

A speaker system with a thermoelectric conversion device includes a basin frame and a vibration system and a magnetic circuit system that are accommodated in the basin frame. The vibration system includes a diaphragm and a voice coil. The magnetic circuit system includes a T-iron, a magnet and a washer, with a magnetic gap between the washer and the magnet and the T-iron. The voice coil moves up and down in the magnetic gap. A thermoelectric conversion device is connected to the speaker including a thermoelectric power generation module, a boost circuit module, and a load management module. The thermoelectric power generation module is fixedly connected to a back surface of the T-iron for thermoelectric power generation. The boost circuit module boosts and regulates a direct current outputted by the thermoelectric power generation module. The load management module performs a power distribution and load management on the boosted new power.

A pressure wave generating element is provided that includes a support and a heat generating layer that is provided on the support and generates heat by energization. Moreover, the heat generating layer includes a fiber with at least a partial metal coating on a surface.

A MEMS transducer for interacting with a volume flow of a fluid includes a substrate including a cavity, and an electromechanical transducer connected to the substrate in the cavity and including an element deformable along a lateral movement direction, wherein a deformation of the deformable element along the lateral movement direction and the volume flow of the fluid are causally related.

This disclosure provides systems, methods, and apparatus associated with an electrostatically driven graphene speaker. In one aspect, a device includes a graphene membrane, a first frame on a first side of the graphene membrane, and a second frame on a second side of the graphene membrane. The first frame and the second frame both include substantially circular open regions that define a substantially circular portion of the graphene membrane. A first electrode is proximate the first side of the circular portion of the graphene membrane. A second electrode proximate the second side of the circular portion of the graphene membrane.

An apparatus, method and computer program is described including: a driver for driving a membrane of a gas-retaining chamber to induce vibrations in the membrane in a first mode of operation, wherein said membrane is configured to surround at least part of a device; and an activator for activating a rapid expander in a second mode of operation, wherein the expander comprises an expandable foam that is configured to inflate said chamber in response to an activation signal.