Side note but I'm convinced that people wanting to improve touch sensitivity in robots need to look at frequency detail of tactile data, not spatial detail. Try this: Put your finger on a bumpy wall without moving it at all and see what you feel. Not much. Now move your finger across the wall. All sorts of detail jumps out. I think the human tactile system is reading changing pressure in the time domain and translating that into the spatial domain as the finger scans across the surface.