"The participants probed the surfaces with the index finger of their preferred hand in a designated direction (perpendicular to the grooves) for as long as they

"The participants probed the surfaces with the index finger of their preferred hand in a designated direction (perpendicular to the grooves) for as long as they wished and at loads and speeds that they established themselves" "...it is observed that while the minimum pattern that could be distinguished from the unwrinkled reference surfaces had a wavelength of 760 nm, the amplitude of this pattern was only 13 nm. This shows unambiguously that the human finger, with its coarse fingerprint structure in the sub-millimeter range, is capable of dynamically detecting surface structures many orders of magnitude smaller and indicates that nanotechnology may well have a role to play in haptics and tactile perception." [1] Feeling Small: Exploring the Tactile Perception Limits https://www.nature.com/articles/srep02617 https://www.nature.com/articles/srep02617