The flat, square, chip-format Nanoscopic Electrostatic Drive (NED) microspeaker comes from German startup Arioso Systems, a spinoff of the larger Fraunhofer Institute for Photonic Microsystems. It measures just 10 to 20 square millimeters, and is made entirely of silicon.
Arioso’s design replaces the conventional loudspeaker membrane with hundreds of moving beams. They use the chip’s volume instead of the surface and are driven by electrostatic forces.
Inside the chip is an array of flexible beams, each one just 20 micrometers in length arranged between a top and bottom wafer. When the voltage of an audio signal is applied to the device, it causes those beams to repeatedly bend toward one another. Air is released through openings in the bottom and the lid, and perceived as sound.
Each beam contains the “muscles” that drive it. That approach allows for an incredible variety of designs – of the individual beams and the entire chip. Functions that could be enabled in MEMS devices such as microphones or earbuds might include instantaneous language translation, health-monitoring features, or the ability to pay for purchases using voice commands.
Using the silicon chip’s volume minimizes its size and costs per device. The company’s goal is to achieve a sound pressure level of 120 dB with a chip area of only 10 mm². The MEMS micro speakers have no outer moving parts and therefore even works without an additional package, and should require less battery for devices such as earbuds for example.
Widespread CMOS fabrication processes can be used, the company claims, to make MEMS micro speaker design scalable for mass markets.