A new type of ultrasound technology promises to make the touch surface of almost any conventional material. As a base, metal, glass, plastic, wood and so on are suitable.
Such chips can work with different surfaces, including when the latter are dirty. As noted in UltraSense Systems, to date, the use has not been implemented in this way. Such technology is likely to find application in AR / VR headsets, car control systems, smart locks and so on.
At the same time, sensors require a minimum of energy and can do without a separate processor. And they work through gloves, so you no longer have to look for special gloves for the winter or answer a call with your nose.
A similar technology is used in ultrasonic fingerprint scanners on Samsung Galaxy S10 and Galaxy Note 10.