Testing Tactile Aids With Blind Subjects

Investigators will design bumps of varying heights, spacings, diameters, and bump shapes (rounded top, flat top, angled top) which give a precise amount of mechanical stimulus to the finger. Subjects will be asked if they could notice a bump on the surface and instructed to make the judgment quickly (\<2 seconds). A psychometric curve, with a standard braille bump serving as the positive, \~100% success rate control, will be constructed

Investigators will fabricate and characterize two bumps of varying widths (ranging from 150 μm to 3 times the bump width, based on fabrication resolution available in commercial tactile aid machines). Subjects will be asked to run their finger across the two bumps (two bumps always form a line, so investigators do not need to ask subjects to orient their fingers) quickly and asked if they felt one bump or two.

"Investigators will coat single bumps with our designer materials (with alkyl and amino functional groups) to improve the mechanical stimuli from a single bump. Subjects will then be asked to perform a similar experiment as the single bump acuity test and the optimal spacing between bumps test. (can you notice the bump? or did you feel one or two bumps)."