Japanese Achieve 3-D Optical Memory on Human Fingernail (moved from ATSNN), page 1

A Japanese research group has reported the remarkable achievement of 3-dimensional optical data storage onto a human fingernail. As reported in the scientific journal Optics Express, structural changes to the fingernail were generated following irradiation with a focussed femtosecond laser. The structural changes allowed the researchers to encode data into a three dimensional array.
The researchers conclude that the array is readable for at least 6 months (the time it takes for a fingernail to regrow), and that recording densities as high as 2 Gigabits per cubic centimeter are possible.

www.opticsexpress.org
Three-dimensional optical memory using a human fingernail

Akihiro Takita, Hirotsugu Yamamoto, Yoshio Hayasaki, and Nobuo Nishida, The University of Tokushima; Hiroaki Misawa, Hokkaido University

Abstract
We realized optical data storage in a human fingernail. A structural change is recorded by irradiating a focused femtosecond laser pulse and is read out with fluorescent observation by making use of an increased fluorescence intensity. The shape of the structural changes drastically depends on the irradiated pulse energy. The fluorescence spectrum of the structure coincided with the auto-fluorescence spectra of a fingernail and a heated fingernail. It is suggested that the increased fluorescence is most likely caused by a local denaturation of the keratin protein by the femtosecond laser pulse irradiation. We demonstrate that the increased fluorescence effect is useful for reading out three-dimensionally recorded data

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An astounding achievement. It doesn't take much imagination to come up with all kinds of possible applications of this work, both helpful and even somewhat sinister.