Fraunhofer IPMS Develop MEMS-Based In-Ear Headphones for the Internet of Voice

Scientists from IPMS (Fraunhofer Institute for Photonic Microsystems) and BTU (Brandenburg Technical University) have developed power-efficient MEMS-based acoustic transducers for in-ear monitors targeted at IoV (Internet of Voice) applications. According to the researchers at Fraunhofer, demand for IoV services is expected to grow over the next several years with ‘hearables’ leading the forefront of smart audio technology. More people are integrating voice-based services — Apple’s Siri, Google’s Assistant, Amazon’s Alexa, into their smart homes, vehicles, and smartphones, and hardware manufacturers are banking on their popularity to develop internet-enabled mobile terminals worn in the ear.

The new MEMS-based acoustic transducers don’t rely on a conventional membrane to produce sound, but instead use a variety of bending actuators, which are situated within a volume of silicon. The scientists designed a new type of electrostatic bending Nano-e-Drive (NED) actuators, which are integrated into 20μm thin transducers. When an audio signal is introduced, the voltage causes the actuators to vibrate and produce sound. To prevent any short circuit on either side, the team bonded a pair silicon wafers with input and output slots on the top and bottom of the actuators.

As mentioned earlier, sound is generated when the voltage from an audio signal vibrates the NED actuators, which push air in microscopically small chambers housed in the silicon chips. The new technology allows manufacturers to build micro speakers using pure silicon, and the scientists created a battery-powered demo platform that’s capable of producing sound pressures higher than 100dB, or roughly the same as Bell J-2A helicopter hovering at 100-feet. The researchers are now looking to miniaturize the technology while increasing the loudness and audio fidelity, with the end-goal being generating 120dB from less than a 10mm2silicon chip.