Dirt-detecting slippers

These are slippers that you wear while walking around your house. They detect that the floor under/around them is dirty, and notify a cleaning robot (vacuum, mop, etc., as are already available) to clean that area.

The slippers could detect dirt around them by shining infrared light out sideways at floor level, and using an infrared camera mounted a little bit higher up to see the shadows cast by dirt particles on the floor, or possibly by other methods. They could detect dirt underneath them using one of the following systems (or something else):
- a multitouch-capable resistive touch digitizer (which exists, but is a rare technology)
- an acoustic system where sound waves are transmitted laterally through the sole of the slipper and dirt is detected by where it causes a discontinuity off of which the sound waves diffract (like how time-of-flight diffraction is used for finding subsurface cracks in metals) or which cast acoustic shadows on the far side of the sole
- an optical frustrated total internal reflection system that operates analogously to the above-described acoustic system.

Also, the slippers will protect your feet from feeling the dirt that you step on, because their soles are more rigid than skin or socks.

Cleaning robots that can be dispatched at will to clean specified areas are already available—e.g. recent Roomba models—and I expect this capability will improve over the next few years (unless iRobot has a patent on the whole concept, which they probably do).

73/515 [2019-07-07]