Gestural control is something with which we're all familiar, thanks to products like the Wii, Apple's multitouch iPhones and iPads, Microsoft's Kinect, and Leap's Motion. But while gestures can be an extraordinarily efficient control mechanism for many pieces of technology, it's more difficult to implement them on smaller devices simply due to the more limited touch-surface real estate offered by, say, a smartwatch. Ultrasound physics and a minuscule device developed by researchers at University of California at Berkeley and Davis may fix this.
The system is called Chirp and it's an innovative development in ultrasound transducer technology. Ultrasound is, of course, best known for enabling sonograms of amazing imagery inside the human body—but if you remember, it was once used as an early form of remote control for TVs. What the UC team have done is take ultrasound emitters and receivers and miniaturized them, stacking a number of the sound systems into a very small array on a semiconductor.
Chirp incorporates everything needed to transmit ultrasound waves, receive them, and process the basic information received when the ultrasound reflects from a "target" in front of the array. Chirp has a sensing area shaped like a small hemicircle above the chip. If you put a finger or your palm into this space you will reflect some of the emitted ultrasound back to the sensors and thus alert the chip that there's a target in its way. Moving your finger will change the quality of the sound echo received by different parts of the sensor array. By processing the complex mass of sound signals it receives back from each part of its array, Chirp can actually work out how an object like a hand or perhaps finger is moving within its sensing range.
Combined with the electronics in, perhaps, a smartphone or TV remote, this gives the system the opportunity to react to some quite complex hand gestures, such as those you may make when trying to set up a game on an Xbox via the Kinect 3-D sensor—although Kinect uses optical sensing systems of a higher resolution. But the tech in Chirp can easily be scaled, so it could be installed in a device like a smartwatch or perhaps a wearable headset like Google Glass. To zoom in to a photo, say, on a smartwatch using Chirp you could perhaps draw your fingers together above the screen of your device.
The system has a couple of advantages over conventional touchscreens or optical sensors. Firstly it doesn't require you to touch the screen, and this sort of 3-D gestural control could allow you to interact in some quite sophisticated ways with a device like a watch. Secondly the processing requirements to analyze ultrasound signals can be slower and less burdensome for a mobile chip to carry out than optical sensors—meaning the sensor doesn't eat up much power, and thus is ideal for mobile devices.
The practical upshot is that 3-D gestural control could be coming to devices as diverse as smartphones, smart watches, wearable computers, and perhaps even your TV. The opportunity for innovative user interfaces, control paradigms, and even apps like gaming simply cannot be overstated, and you may soon find yourself coding for a touch-sensitive device its users never actually touch. The effects may literally feel like "magic." Given that Apple has patented aspects of a 3-D gestural UI, this code may first run on iOS.