New-Tech Europe | Q2 2020 | Digital Edition

Haptic feedback: the next step in smart interfacing Micromachined transducers turn ultrasound into touch

By Denis Marcon & Xavier Rottenberg , IMEC

By giving the user a sense of touch, haptic feedback adds a new dimension to current user interfaces – enabling exciting applications like human-machine interfacing and remote surgery. Touchless user interfaces, such as haptic and voice, will play a critical role in the low-touch economy which is expected to emerge in the post-COVID-19 era. At the heart of the first-generation of haptic based interfaces are bulky piezoelectric ultrasound transducers, which are cumbersome in use, impede a very fine interaction and limit end-product integration possibilities. To meet these shortcomings, imec’s Denis Marcon and Xavier Rottenberg introduce compact micromachined ultrasound

transducers to widen the field of applications. Two different technology platforms – Si-CMOS and display-manufacturing based large area – are being developed and offered to companies. A sense of touch Ultrasound are sound waves with frequencies that are higher than what is audible to the human ear, i.e. larger than 20kHz. Technologies making use of ultrasound waves have been used for many years, mainly for sensing applications. The best-known example is diagnostic imaging, also known as sonography, which was introduced as a diagnostic tool back in the 1940s. In this application, pulses of ultrasound are sent into tissue, and the echo pulses are displayed as an image that reveals internal body structures.

Few people are aware that the ultrasound technology can also be used to equip smart systems with haptic feedback, giving the user a sense of touch. In such an application, the technology is implemented as an actuator rather than as a sensor. The actuator emits ultrasound energy – a type of mechanical energy characterized by pressure waves that propagate through air. Interesting applications emerge when the ultrasound energy can be perceived by the receptors on our fingers. This can enable enhanced human-machine interfaces for automotive, advanced display applications, or allow a finer interaction with robots in a manufacturing environment. In one implementation, the user can be ‘physically’ touched by the smart system.

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