Recently, XMEMS Laboratories introduced Tomales, a scalable single-chip MEMS piezoelectric driver tweeter. According to reports, the MEMS micro-speaker can achieve large audio coverage from 20Hz to 20kHz, and has the characteristics of small size, light weight, low power consumption, and strong scalability, which can meet the application of small products such as TWS headphones and hearing aids.

With the popularization of active noise reduction, spatial audio, 360-degree surround sound and the continuous reduction of chip costs, the TWS headset market has been completely detonated, and the market penetration rate has increased significantly. Moreover, major consumer giants have also entered the TWS headset market one after another, and they are constantly iterating and updating, hoping to get a share of the TWS outbreak.

With the advancement of science and technology, TWS headphones are no longer mediocre. The addition of various voice assistants and spatial noise reduction has led to a surge in the number of electronic components and an increase in device power consumption. In addition, the small space inside the earphone also limits the development of multi-functional TWS earphones. Therefore, in order to ensure the longer-lasting durability and multi-functional development of the headset, terminal manufacturers have put forward higher hardware requirements to upstream core component manufacturers.

In TWS headphones, the speaker and battery take up most of the space. With the increase of functions, the internal space of TWS headphones is further tightened. Therefore, optimizing the size and power consumption of speakers has become the best solution under the premise of ensuring battery life. In order to meet the development needs of the TWS earphone market, many manufacturers have also released MEMS speakers with small size, low power consumption and strong scalability to replace the traditional coil speakers to meet the application needs of the market.

MEMS speakers could be used in headphones and smart glasses

Recently, XMEMS Laboratories introduced Tomales, a scalable single-chip MEMS piezoelectric driver tweeter. XMEMS MEMS speaker technology is mainly based on the inverse piezoelectric effect of piezoelectric MEMS materials. It works by applying a voltage to the piezoelectric MEMS. When the piezoelectric MEMS receives an electrical signal, the silicon membrane converts the transmitted electrical energy into mechanical energy for expansion, contraction and sound waves. Compared to conventional speakers, XMEMS' piezoelectric MEMS have a greater range of mechanical motion, which can produce greater audio effects.

Tomales are monolithic MEMS tweeters that can implement multiple application scenarios. According to xmems, Tomales uses a single-chip architecture. The advantage of this structure is that the driver and diaphragm are integrated on the same silicon chip. High integration helps to improve the consistency of the response frequency of each device, improve the ANC bandwidth of non-steady-state noise, and reduce the matching and calibration time in the product production process. The use of this architecture not only eliminates the recovery process of traditional speaker springs and suspensions, but also greatly restores the sound quality of the original audio, enhancing the user experience.

At the same time, the MEMS speaker also adopts IP58 dust/waterproof design and packs 6.05x8.4x1.15mL GA, which further reduces the difficulty of speaker layout and the space ratio between the device and the speaker. It is very suitable for headsets, smart glasses, AR/VR and other devices with small internal space and designated audio orientation.

In terms of product performance, according to XMEMS, Tomales has adopted its own unique second-generation M2 speaker unit architecture, which has been optimized to achieve the effect of small speaker sound pressure. In the decibel test experiment at a distance of 3cm from Tomales, when the operating frequency is 2kHz, the decibel test result is 75dB. When the working frequency is 4kHz, the decibel test result is 90dB model>90dB model>90dB model>90dB model>90dB model>90dB model>90dB model>90dB model>90dB model>90dB model? >90dB Model">90dB Model">90dB Model">90dB Model">90dB Model">90dB Model">90dB Model">90dB Model">90dB Model">90dB. When the working frequency is 10kHz, the decibel test result is 108dB. The sound field effect generated by different operating frequencies can meet the needs of general product applications. At present, the new product is still in the sample stage and is expected to be mass-produced in 2022. XTWS in-ear headphones.

MEMS speakers powered by nano-electrostatics

According to foreign media reports, the Fraunhofer Institute for Optical Microsystems successfully developed a MEMS micro-speaker using nano-electrostatic drive technology in October this year. The speaker is reportedly made of 100 percent silicon, and even the speaker's acoustic diaphragm has been replaced by a curved band made of silicon wafers. As can be seen from the raw materials used, this MEMS microspeaker has a great cost advantage.

The speaker mainly produces sound in the ADSP-21061KSZ-160 silicon chip through nano-electrostatic driving technology. The chip produces a very small electrode gap during the etching process, and the high electrostatic driving bending belt generated by the electrode gap produces bending motion in the chamber. When the flexing band within the chamber performs a flexing motion, the vibrations push air out of the chamber and create sound. The speaker can emit up to 120dB of sound pressure with an effective chip area of only 10mm2 (the replacement air volume is about 0.5mm3).

At the same time, the curved band of the loudspeaker can also be laid out and optimized according to the frequency range of different applications. You can also increase the thickness of the wafer during the wafer production stage if you want to increase the sound pressure level of the speaker.

According to reports, the MEMS micro-speaker can achieve large audio coverage from 20Hz to 20kHz, and has the characteristics of small size, light weight, low power consumption, and strong scalability, which can meet the application of small products such as TWS headphones and hearing aids.

Epilogue

With the increase in the functions of wearable devices such as TWS, AR/VR, and smart glasses, MEMS speakers with small size, high power consumption and high frequency have become the most advantageous solution. The successful research and development of 100% silicon MEMS speakers will help terminal manufacturers to control product costs and improve product market competitiveness.