…the answer continues to be a swipe, but one in which you don’t actually need to touch the screen with your finger. Researchers call these no-contact computer screens touchless positioning interfaces (TPI).
Source: Novel Nanostructures Could Usher in Touchless Displays – IEEE Spectrum
This is a long way from practical application but the concept, that is a touch-less touchscreen, has obvious applications in dentistry. No touching means no cross contamination which means better aesepsis.