Siemens Demonstrates Fingertip Chip Sensor

A unique personal identification system based on fingerprint pattern recognition was demonstrated at the Smart Card exhibition Feb. 17-19 in London. This system, developed by Siemens researchers in Munich-Perlach, Germany, recognizes and evaluates the characteristic patterns of a fingerprint in about half a second (Fig. 1).

This biometric sensor finds an average of 12 characteristic patterns on a fingerprint area of some 100 mm², allowing unambiguous identification. It offers the advantage that no identification number or password need be memorized to establish a personal identity, nor need any card be carried that can be lost. There is no possibility of the identification data being passed on to anyone else for subsequent fraudulent use. It is only necessary to hold the sensor card in the hand to use it.

1. Identification can be made soon after the finger is placed on the sensor surface.

2. Fingertip ridges are detected by the capacitance sensor array.

A reference image of a fingertip of a person must be "enrolled" before the sensor can be used. The characteristics of the fingerprint are assigned to the identity of the enrolled person. When that person requires access to be provided, the system is first provided with that person's identity. A finger image taken by the sensor is then compared with the stored reference pattern, and a message is displayed showing whether the identity has been verified. The algorithm used detects the position of the end and the beginning of each ridge of the fingerprint.

The resolution of the surface of the sensor is about 50 µm, corresponding to 500 dots per inch, so that it meets all currently prevailing standards for fingerprint recognition systems. It can recognize about 50 shades of gray, while an analog-to-digital converter makes the image data available in digital form. Power consumption is quoted as 6 mW from a 5 V supply.

The fingertip sensor offers a simple and convenient method of identification that can be controlled by the user for such applications as access control to computers, mobile telephones, automobiles and private homes. Graham Nott, sales and marketing manager of chip card ICs at Siemens (Bracknell, UK), said, "Commercial products using this technology are scheduled for the fourth quarter of this year."