A thermophone includes an inner core and an outer shell coaxial with the inner core. The inner core and outer shell enclose a volume filled with gas. A pair of posts extend radially from the inner core to the outer shell and extend longitudinally between the inner core and the outer shell. At least one longitudinal slot is formed along the outer shell and a fluid seal covers the slot. A thermoacoustic active element is disposed in the volume and heated by modulated current to generate alternating pressure on the outer shell and produce acoustic signals.

A MEMS transducer for interacting with a volume flow of a fluid includes a substrate which includes a layer stack having a plurality of layers which form a plurality of substrate planes, and which includes a cavity within the layer stack. The MEMS transducer includes an electromechanical transducer connected to the substrate within the cavity and including an element which is deformable within at least one plane of movement of the plurality of substrate planes, deformation of the deformable element within the plane of movement and the volume flow of the fluid being causally correlated. The MEMS transducer includes an electronic circuit arranged within a layer of the layer stack, the electronic circuit being connected to the electromechanical transducer and being configured to provide a conversion between a deformation of the deformable element and an electric signal.

A method for activating a gas, wherein an electrically conductive aeromaterial having a pore space comprising the gas is electrically contacted and at least one electric current, which varies over time, flows through the aeromaterial, wherein the aeromaterial exhales gas from the pore space when the electrical power consumption is increased and inhales gas from the surroundings of the aeromaterial when the power consumption is decreased, and wherein a temporally pulsed current having predefined pulse power levels, pulse durations and pulse spacings is fed through the aeromaterial and the temperature of the aeromaterial is changed by the time-varying current by 100° C. or more within one second or less. The invention also relates to an electrothermal gas actuator and to uses of a gas actuator.

A thermal excitation acoustic-wave-generating device includes a first heating element, a substrate that includes a main surface along which the first heating element is disposed, and a facing body that faces the substrate with the first heating element interposed therebetween. The substrate and the facing body define a path for an acoustic wave. A length of the path is close to a whole number multiple of ¼ of a wavelength of the acoustic wave.

An underwater sound generation device may be used for effective control of algae and other microorganisms in ponds and lakes. The sound projector may comprise a thermoacoustic sound transducer and an electronic unit for controlling the operation of the projector. The thermoacoustic projector may include a freestanding carbon nanotube (CNT) film encapsulated between two vibrating plates. The inert gas filled thin acoustical cavity provides a piston-type displacement of the plates and supports a high-temperature operation. A power supply driver, controlling the operation of the sound radiating system, may include a pulse generator, high-power switch amplifier, and a cable, connecting the projector with an electronic driver. The sound control system may provide an omnidirectional sound pressure level in a wide frequency range to affect the algae growth ecosystem over large distances.

A carbon nanotube thermophone is provided which includes a urethane frame having mounting holes at corners of the frame. Screw holes in the frame are provided for a cable holder. A square shaped carbon nanotube material chip is positioned within the urethane frame. The carbon nanotube material chip can comprise multiple carbon nanotube sheets to electrically tune the impedance to match a driving amplifier impedance load. Wooden spacers assist in positioning the carbon nanotube material chip. A first end of a cable is soldered to the carbon nanotube material chip at electrodes of the material chip. A high temperature rated silicon sealant is used for attachment points on the thermophone.

A carbon nanotube thermophone is provided. The thermophone includes high temperature rated shells as protective walls as the top and bottom housing of the thermophone with carbon nanotube sheets affixed between the shells. The shells act as acoustic windows that match the surrounding frequency and acoustic radiation medium. A high temperature rated sealant gasket is used to enclose the shells of the thermophone where gas holes are inserted for interior heavy gas filling. The acoustic resonant frequency is defined by the dimensions of the housing of the thermophone and the sound speed of the filled heavy gas. Each carbon nanotube sheet has an electrode at both ends. Multiple carbon nanotube sheets can electrically tune the impedance to match a driving amplifier impedance load.

In one aspect, the present invention provides nano-scale heaters, such as nano-scale thermoacoustic loudspeakers comprising suspended metal nanobridges prepared using atomic layer deposition (ALD). The loudspeakers of the invention are capable of producing audible sound when stimulated with an electrical current or other energetic stimulus. In another aspect, the present invention provides methods of preparing and using such nanodevices.

A thermoacoustic device includes a substrate, a first electrode and a second electrode, at least two supporting members, and a first carbon nanotube film. The substrate includes a surface. The first electrode and the second electrode are located on the surface of the substrate and spaced from each other. The at least two supporting members are spaced from each other and respectively located on surfaces of the first electrode and the second electrode. The at least two supporting members include a plurality of carbon nanotubes parallel with each other and substantially perpendicular to the surface of the substrate. The first carbon nanotube film is supported by the at least two supporting members and has a portion between the at least two supporting members suspended above the substrate. The supporting members electrically connect the first carbon nanotube film with the first electrode and the second electrode.

A passive carbon nanotube transducer is provided. The passive carbon nanotube transducer includes shells as protective walls for the top and bottom housing of the transducer with carbon nanotube sheets affixed between the shells. The shells act as acoustic windows that match the surrounding acoustic medium. A gasket encloses the shells and carbon nanotube sheets of the transducer. Each carbon nanotube sheet has an electrode at both ends. Multiple carbon nanotube sheets are capable of sensing sound induced environment temperature deviations and converting electric voltage or current for passive acoustic detection.