Recently, there has been rapid progress in the field of information technology, which has led to the need to generate, store and transport a large amount of information, while ensuring data security. To meet future demands in information technology, femtosecond laser pulse processing offers a powerful tool for developing new high-capacity devices, as it enables the fabrication of three-dimensional (3-D) structures within a wide range of Transparent materials.
Nail storage is a method of writing data into a human fingernail with a pulsed laser. Fluorescence of the nail, when exposed to ultraviolet light (UV), increases at the points where the data are written. Data can be read from the fingernail using a microscope while irradiating the nail with UV energy.
Recent experiments with Yoshio Hayasaki, from Tokushima University (Japan), have involved small regions of a single nail, measuring approximately two millimeters (square). A pulsed laser, at a wavelength of 800 nanometers (nm), is used to write the data into the nail. Each data bit is approximately 0.003 millimeters (mm) in diameter. The individual data bits are spaced 0.005 mm apart, in three layers at depths of 0.04, 0.06 and 0.08 mm within the nail.
Nail storage has a limited life because human nails grow outward. The average human nail is completely replaced by the body every six months, assuming the nail is cut short at regular intervals. Nail storage has been suggested as a biometric means of identification, and also for storing critical medical information for use in emergencies.