New Paper-Thin Speaker Can Be Used As Wallpaper For Sound-Blasting Surface

Jul, 2022 - By SMI

Researchers developed new flexible, thin-film device that can turn any surface into a low-power, and high-quality audio source

High-performance, lightweight, ultra-thin, energy-efficient and low-cost loudspeakers that can be used large area are becoming increasingly popular to emerging applications such as immersive entertainment and noise control. Researchers at MIT developed such ultra-thin speaker that makes sound producing surface. This unique design is easy to produce at scale and energy efficient, as reported by the team.

Normally speakers function by creating vibration in a membrane that further manipulates the air above it producing sound waves. Speakers used in headphones or other audio systems use electrical currents and magnetic field to produce sound waves. However, the thin-film speakers use piezoelectric materials that vibrate in response to the voltage application. Such speakers are used in phones and TVs. These thin film speakers have some limitations. In the new study, the researchers redesigned thin speakers in a way that they can be put on different surfaces. The team turned the material into a raised domes grid instead of having the entire membrane surface vibrate. These raised domes vibrate separately. The team sandwiched a thin (8 micrometers thick) layer of a piezoelectric material between two PET plastic layers.

Furthermore, one these PET layers consists a grid of small holes, which the piezoelectric material protrudes from. The lower layer of PET provides protection to the membrane and this allows the speaker to be attached to a surface. The resulting speaker is only 4.7 inch thick and weighs just 0.07 oz (2 g), and it consists numerous tiny domes that measure 15 micrometers high. The team tested the device by mounting it to a wall and measuring its output with a microphone 30cm away. The speaker produced sound at around 66 decibels with 25 V electricity at 1 kHz, and 86 dB at 10 kHz.