We Know Who You Are

In order for an electronic component to gain a strong foothold in the lucrative million-unit market of consumer electronics, it has to be small, unobtrusive and inexpensive. Until recently, these simple and unassailable parameters have prevented cell phone and PDA manufacturers from adding security ID devices to their products. Fingerprint Identification technology has been too cumbersome, unattractive and expensive.

But Fujitsu Microelectronics America Inc. (San Jose, CA) has broken both the size and price barriers with its MBF 300 Fingerprint SweepSensor, and it has been rewarded for its effort by having been chosen "Best Product of the Year" from the readers of Design News.

The SweepSensor is a capacitive sensor that is composed of a two-dimensional array of metal electrodes, each acting as one plate of a capacitor. The finger acts as the second plate. As the finger is swept across the sensor surface, the unique contours of the skin produce varying capacitor values across the array. The resulting discharge voltages are read, forming an accurate image of the fingerprint.

While security-oriented products have gained increased attention since the 9/11 attacks, the Fujitsu SweepSensor was not designed as a sophisticated high-tech ID control mechanism. Instead, Fujitsu aimed for the high-volume, low-cost consumer electronics market—the highly cost-competitive world of cell phones and PDAs. "The most important challenge the MBF 300 solves in fingerprint recognition is size and cost," says Doug McArthur, director of the Biometric Sensor Product Group at Fujitsu.

According to McArthur, sweep sensor development that grabs an image from just the tip of the finger has helped to break the size barrier. The small size also helps Fujitsu transcend the price hurdle—for cell phones and PDAs, that means below $10. "Until sweep technology, you were stuck with capturing a full fingerprint on a large plate of silicon sensor, and silicon sensors as big as your thumb are expensive."

With high volume consumer products, silicon equals cost. "In the silicon market, they try to make the sensor as small as possible because it has a direct effect on the cost," says Prianka Chopra, analyst at Frost & Sullivan Inc. (San Antonio, Texas). "So companies are trying to reduce the amount of silicon, and the sweep is the way to do it because the area is large enough to capture just the top portion of the finger, about one-fifth of the finger." The actual size of the sensor on the MBF SweepSensor is 1.28 x 0.2 cm, considerably smaller than earlier models with sensors averaging 1.28 x 1.5 cm.

The cost reduction breaks the $10 barrier that precluded the use of fingerprint ID technology on low-cost, high-volume consumer products. "The Fujitsu sensor is $8 to $10 per unit in a quantity of 1,000," says Chopra. She notes that full-fingerprint sensors remain in the $20 to $30 range, so the ability to grab and identify just a portion of the fingerprint suddenly brings a previously expensive technology into consumer product consideration. "The cost of a cell phone is under $100, so how much more can you add to the cost before consumers quit buying?" asks Chopra.

Targeting High-Volume Apps

Fujitsu is clearly targeting the high-volume consumer market and the company is seeking the coveted design wins that ensure the component becomes part of the product. With cell phones, in particular, this translates into big orders. "With cell phones it's always in millions-per-month," explains McArthur. The turnaround from component introduction to the delivered finished consumer products takes roughly a year, so the Fujitsu SweepSensor, introduced in March 2002, will soon begin appearing on phones and PDAs.

Reducing the size of the sensor area delivers more than just cost advantages for Fujitsu. The minute size of the MBF SweepSensor means that it's possible to attach it to a product that competes to be small. Putting a sensor the size of your thumb on a tiny PDA or cell phone is not a pretty sight. "Now it's small enough to fit on the back panel and not look really ugly," says McArthur.

The small sensor array also allows for more control-area room on the device. "The array is no longer the dominant area of the chip, so the control area becomes the dominant area," said McArthur. "With the array only 30 or 40 percent of the chip, the rest is processing, which allows you to add horsepower into the sensor. That opens up the roadmap to more advanced IP-intensive fingerprint ID."

The Design News new product judge, Michael Ruane, picked MBF Fingerprint SweepSensor for its size and its sophistication in biometric sensing. He also likes its low power needs and powerful software drivers. Ruane notes that Fujitsu's product combines a CMOS technology capacitive sweep sensor for converting a fingerprint into a 500 dpi image that yields "minutiae" features that can be matched to stored fingerprint patterns.

Frost & Sullivan's Chopra contends that other companies have also introduced low-cost fingerprint ID technology. "Fujitsu was not the first," said Chopra. "Atmel [Corp., a semiconductor company in San Jose, CA] was actually the first. They use a heat-based sensor." Chopra states, however, that Fujitsu's technology is riding the market drift in low-cost fingerprint ID. "The sweep is definitely the trend in the market." Chopra points out that the Atmel device is getting some traction at HP where it's embedded into new products. She notes that Atmel has also been able to get its sensor under the $10 barrier that opened doors for Fujitsu.

Whatever the potential competition, Ruane believes Fujitsu has a market edge on the low-cost ID market. "I think they'll enjoy a market advantage with this MBF 300," said Ruane. "Fujitsu will have competition in the basic technology, but I see no one at the moment who can offer a competitive, low-power and flexible sensor that also has integrated capture software."