Most smartphones have at least three buttons on them — one for the power and two (as a rocker) for the volume control. Some phones have more. Maybe a “do not disturb” switch, a dedicated camera button, or a virtual assistant button. Buttons and switches are simple and fundamental. But their days could be numbered with the arrival of new technology based on ultrasound.

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The era of the humble button and the trustworthy switch could be over, not only on smartphones but also inside cars and on home appliances. Not only that, but the use of ultrasound means that touch, tap, swipe and push interactivity can be added to almost any surface.

A company called Ultrasense Systems has recently come out of stealth mode to reveal its new ultrasound tech, a sensor-on-a-chip that can add touch and gestures motions to almost any material, of almost any thickness. Because it uses ultrasound, it is immune to moisture, dirt, oils, and lotions. This means it can be used in a wide range of applications without compromising the experience.

There are two big problems with buttons on smartphones. First, every button needs a cut-out, a hole. A hole is bad news when it comes to waterproofing and dustproofing. Secondly, every button needs a fairly flat edge surface. In the age of curved displays, there can be little or no edge available for a button cut-out, making it difficult to combine the two.

An ultrasound sensor addresses both of those issues. Since no cut-out is needed then no additional waterproofing is required. And at just 1.4mm by 2.4mm, the sensor can be used almost anywhere. Such versatility means it can be used in new places, adding interaction previously not possible. For example, on the back of a smartphone, a series of these small sensors can allow for tapping, sliding and tracking, with the most obvious use case being a trigger to take selfies. Since you are holding the phone with one hand, a tap on the back to trigger the photo is very natural. Another smartphone use case is gaming buttons (air triggers) along one edge for use when holding the phone in landscape.

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Ultrasense’s sensor contains the transducer, the analog circuit, and a microcontroller. The last part is important as it means the sensor-on-a-chip is completely self-contained and doesn’t require an external program to analyze the ultrasound readings. Instead, there is a simple way to interrogate the sensor. You need one sensor per button and, arranged in a line of four sensors you can detect swiping; a simple trackpad requires five sensors. Each sensor can be configured to use a different frame rate. For a touch sensor, it will default to 40Hz, for a power button you would use 5Hz, and for a gaming trigger, you might want 100Hz.

What do you think? Do you want to see ultrasound sensors on your phone rather than buttons? What about the natural feedback you get when you “click” a button, do you need that? Let me know in the comments below.

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