The IMEC research institute (Leuven, Belgium) has developed a piezoelectric Micromachined Ultrasound Transducer (pMUT) array that is compatible with flat-panel-display (FPD) process technologies.
The array can produce acoustic pressures in mid-air of above 1kPa and relevant for mid-air haptics and directed sound, IMEC said. The thin-film pMUT array allows low-frequency, high-pressure devices for large volume mid-air applications. Peak pressures of approximately 1.5 kPa in air at resonant frequencies in the range of 200Hz to 400kHz. This replicates the performance metrics demonstrated for mid-air haptic feedback on IMEC’s silicon wafer pMUT platform.
One company that has long pursued mid-air haptics is Ultraleap Ltd. (see Ultraleap raises £60m to take on the metaverse) although with a greater focus on software algorithms and use cases.
IMEC has moved the making of pMUTs from silicon wafer based processes to FPD-based processes and this could be significant in preparing pMUTs for integration in smartphones and car dashboards. Applications could include vibro-haptics, time-of-flight (3D) sensing or gesture recognition. The technology can be used to create touchless, interactive, screens in automotive and consumer applications, or used in gaming.
Ultrasound technology can be used to give a sense of touch or button clicking without touching the object.
A better haptic
IMEC asserts that current technologies require either large piezoelectric elements that produce relatively high frequencies and low resolution or small silicon-based micromachined transducer arrays can enable high resolution haptic feedback but only at short distance in a small area.
IMEC’s FPD-compatible pMUT technology can provide high resolution at greater distance in front of a screen but at high resolution.
Erwin Hijzen, program director for MEMS and ultrasound, said IMEC is looking to form partnership deals for volume manufacturing on large-area panels and plates.
“The possibility to integrate our pMUT technology into large panels and displays is a key milestone in realization of our vision on large area sensor surfaces. We started with ultrasound transducers for in-body imaging and now moved to mid-air applications such as haptics,” said Xavier Rottenberg, and IMEC Fellow in sensors and actuators.
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