January 2002

Prototype

Continued from page 4

By Technology Review

Fit to Print

Fingerprints make terrific forensic tools or biometric identifiers-as long as they're clear. Bad prints, whether smudged by ink or by scanner, mean bad data. A team at NTT Telecommunications Energy Laboratories in Kanagawa, Japan, says it has developed a sensor that can better capture the likeness of a human fingerprint through tactile means, even if the finger is sweaty or the sensing equipment wet.

The sensor is composed of an array of circuits on a touch pad overlaid with 60,000 microscopic protrusions (photo). When a finger presses the sensor, its individual ridges push down on a corresponding set of protrusions, each of which then triggers a current in an attendant electrode. Each activated circuit is translated into a pixel in a digital image of the fingertip. NTT researcher Norio Sato says that the device will enable outdoor applications such as car locks, which have been stymied by the smudge factor. The sensor is several years from availability.