Tiny MEMS sensor frees space in hearables

Tiny MEMS sensor frees space in hearables

Technology News |
By Rich Pell

This 2D motion sensor is Nanusens first product and is being aimed specifically at the earphone market. It is due to sample in 4Q19 and be in volume in 2020.

X-ray of an earbud showing battery and electronics. Source: Nanusens.

Most MEMS sensors use different silicon wafers for the MEMS and signal conditioning ASIC, resulting in a more complex manufacturing process and larger component. Nanusens uses 0.18 micron CMOS processes at SMIC and TSMC and uses a Chinese assembly house, JCAP, part of JCET, to apply vapor etching to release the moving mass, said Josep Montanya, CEO of Nanusens.

The moving mass is created by etching away the intermetal dielectric through openings in the passivation layer using hydrofluoric acid vapor (vHF). The holes are then sealed and the chip packaged as necessary. As standard CMOS processes are used with minimal post-processing the sensors can be directly integrated with active circuitry and the sensors can potentially have high yields similar to CMOS devices.

CMOS electronic circuitry and microelectromechanical system (MEMS) co-exist in one die. Source: Nanusens.

“We are in a unique position of being able to provide more space inside earbuds for designers to use as they wish with our nano-sensors. While some manufacturers want more battery life by using a larger battery or a supercapacitor, others want to use some of this freed-up space for features such as memory so that songs can be stored locally on the earbud. This is another way to extend the battery life as songs would not need to streamed over Bluetooth, again giving longer audio on the go.”

“We have started discussions with the leading players in the value chain to make them aware of our innovative technology so that they can start the design-in process,” added Montanyà.

Next: What’s planned

Nanusens MEMS sensor can be used to implement tap and double tap for control, wake-on-movement and sleep-on-rest functions, and, soon after, a 3D accelerometer. A bone conduction sensor for noise cancellation is next to be integrated into the single chip solution. Chips will be available in a small package such as WLCSP or as bare die that can be attached directly to the PCB. With a volume of about one cubic millimeter the Nanusens will save 3 cubic millimeters compared with conventional MEMS components, Montanya estimates.

Chip layout showing two Nanusens motion sensors integrated with the control electronics on the same die. Source: Nanusens.

Nanusens is also developing a bone conduction sensor for noise cancellation – due in 2019 –a 3D accelerometer for step counting, gyroscope and compass for head position sensing and microphones – all due in 2020.

The company is also working with Bluetooth SoC reference designers and a Series A round of finance of about €10 million to €15 million.

Related articles:
Nanusens moves to UK to exploit crowdfunding tax break
Nanusens creates nanosensors in CMOS
Baolab buries MEMS into CMOS production line

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