Researchers at the Tokushima University Department of Optical Science and Technology have worked for five years on technology that etches readable electronic data on a human fingernail. Three researchers announced in June that they had successfully used lasers to put as much as 5MBs or 640KBs of data on a fingernail, including sufficient memory to store credit card information or medical records. When costs are lower and safety issues are handled, there should be significant business potential for a product, says Dror Sarid of the Optical Data Storage Center at the University of Arizona. Fingernail-etched-in information could be used to identify people and encode medical data, or even identify lost children. Others agree that the idea of information encoded onto the human body is not outrageous, including Mr. Sarid's colleague, Alan Kost, who finds the subject of writing on the human body to be very interesting. The work is a mid-point achievement between the use of conventional modes of data storage to new biological-based media. The scientists started by polishing a tiny, clipped piece of fingernail to a smooth finish. They then passed small energy impulses through a microscope while focusing it to different depths with an objective lens. The amount of energy used for writing a bit of information is small. To read the data, a fluorescence microscope was used that included a high-intensity light source that generates white light similar to daylight.