Monday, June 15, 2009

Fingerprints friction theory rejected

Scientists say they have disproved the theory that fingerprints improve grip by increasing friction between people's hands and the surface they are holding. Nobody is sure of the exact function of fingerprints, but improved grip has long been a favoured theory. However, in a series of tests to measure friction between a finger and a piece of acrylic glass, it was debunked by a University of Manchester team. The study appears in the Journal of Experimental Biology.

Dr Roland Ennos designed a machine which enabled him to measure the amount of friction generated by a fingerprint when it was in contact with the acrylic glass. The machine was then strapped to the index finger of one of his students. Dr Ennos expected the amount of friction to increase in proportion to the strength at which the acrylic glass was pushed against the finger. This would have supported the theory that the fingerprint was helping to improve grip by ramping up friction levels. However, the results showed that friction levels increased by a much smaller amount than had been anticipated.

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