|Covid-19|Optical trackpad Wikipedia
An optical trackpad is an input device based on an optical sensor, which detects the displacement of a finger that is moving on top of it. The sensor is used typically in smartphones where it replaces the D-pad. The main advantages over a D-pad are:It can track movements in 360 degrees and with varying speeds.
It uses space efficiently, without the need for small buttons that are difficult to press.
Next to browsing through menus, it can drive a mouse cursor in point&click interfaces.
In comparison with trackpads, it detects actual skin displacement, instead of displacement of the center of the area being touched.