Accelerometers are being integrated into some mobile handsets to enable such applications as intelligent user interfaces that that let users input commands through gestures; indoor GPS functionality, which calculates the movement and direction of the device after contact is broken with a GPS satellite; and intelligent power consumption, which automatically shuts off circuitry when it is not needed. The high-profile Apple iPhone uses an accelerometer to detect the orientation of the device and automatically change the display from portrait to landscape when the phone is rotated.

Though accelerometers have declined rapidly in price over the past few years, making them more attractive options for handset manufacturers, the common wisdom is that they must dip below the $1 threshold to achieve widespread uptake in cellphones. That will occur in 2010, according to a report by ABI Research. Some have speculated that by 2012, half of all handsets will include accelerometers.

But not all market watchers are sold.

Arguments for and against
"When I see forecasts that say in five years every cellphone will have an accelerometer—while personally I’d love to see it—the numbers just don’t add up," said Marlene Bourne, president and principal analyst at Bourne Research LLC. According to Bourne, the average selling price (ASP) for tri-axis accelerometers is now roughly $1.50. Even at $1, Bourne said, incorporation of accelerometers will remain a pricey gamble for handset manufacturers.

Incorporating the devices for functionality in high-end phones like the iPhone makes sense, she said, but it’s a different proposition for even midrange handsets. "It’s hard to believe that you are going to put a sensor that is $1.50 or even $1 into a mass-market cell phone, where the BOM is as low as it is," Bourne said.

Douglas McEuen, a senior analyst at ABI Research, countered that the success of the iPhone and Nintendo’s Wii gaming system (which also uses accelerometers) has prompted some to make the leap to motion-sensing MEMS. "I would argue that you almost have to [add motion-sensing capability], just because these products [iPhone and Wii] have been so successful," McEuen said.

McEuen forecasts that accelerometer shipments for handsets will grow by 139 percent, to 437 million units, between 2007 and 2012, representing use in 30 to 40 percent of all handsets five years from now. As MEMS technology becomes increasingly CMOS-based over that period, he said, its uptake will accelerate.

Penetration factors
MEMS accelerometers were used in 1 to 2 percent of cellular handsets shipped in 2007 and will appear in 4 to 5 percent of handsets this year, according to Mathieu Potin, an analyst at Yole Developpement. Further penetration, Potin believes, will depend on four factors: cost, customer options, battery life and the business case for cellular network operators. Potin believes the penetration rate could rise very quickly if all or most of those factors are satisfied, particularly if operators see the potential to increase revenues via new services.

Jeremie Bouchaud, head of market research at Wicht Technologies Consulting said that in order to fit their devices within a cellular handset BOM, some companies will field two-axis accelerometers with an ASP of about 50 cents within the next five years. "I think there will be some solutions with some compromise in performance to perform very specific tasks," he said.

Commoditization
"Some companies are willing to take basic sensors and build on them with software," said Benedetto Vigna, VP and general manager of the MEMS, health care, RF and sensors division at STMicroelectronics NV, while others are willing "to pay for more-expensive sensors." Vigna said he expects to see a big volume jump in sensors supplied to wireless handsets by the end of this year or early next year.

Bourne warned that the aggressive price reductions achieved by accelerometers in recent years may work to the devices’ detriment. In a report released April 30, she called the consumer electronics market—particularly the cell phone sector—a "double-edged sword" and warned that the commoditization of MEMS sensors could lead to near-term revenue paralysis.

But ABI’s McEuen believes the commoditization of MEMS is 20 years away. "A MEMS device is so specialized," he said. "You can tell by the small number of quality MEMS vendors in the market that this is something not many people can do."

- Dylan McGrath
EE Times