Benedetto Vigna, director of ST's MEMS Business Unit, said its device is optimized for Wii's freestyle controller. ST's system-in-package consists of two components: a three-axis MEMS accelerometer sensor and an interface chip that translates movement and inclination into electronic signals, amplifies them and provides analog output.

The motion sensors used in the Wii controllers are not necessarily "pin to pin" compatible, said ADI's Mannherz. "But it's a common practice among game console companies to hedge their bets and secure two suppliers for such key components," he said.

The use of motion sensors in consumer devices is not new; indeed, their use mobile handsets and notebooks is on the rise.

ST's three-axis linear accelerometer has been used in applications such as mobile phones, PDAs and other battery-powered products to enable user interfaces based on movement.

The same technology has also been used as the "airbag of a computer," said ST's Vigna. For example, an accelerometer embedded in a notebook computer could sense it falling off a desk and move the hard drive's head to a safe area so that it wouldn't crash onto the drive.

ADI, which claims to be the leading supplier of motion sensors for auto airbag systems, began researching MEMS technology 15 years ago "as a platform to create highly reliable, extremely fast devices that could sense motion," Mannherz said.

ADI's two-axis accelerometer is in game cartridges designed five years ago for Nintendo's Game Boy Advanced. But the recent emergence of a highly integrated three-axis accelerometer is making it much easier and more cost-effective for game console makers to integrate motion sensors into mainstream videogame controllers, said ADI marketing manager Christophe Lemaire.

ADI's motion signal-processing technology has been used in consumer devices ranging from a guitar effects controller to "intelligent" golf clubs.

By transferring core MEMS sensor technology to the videogame world, "you can simplify [game play] and make it more natural," ST's Vigan argued. "You don't need to worry about which buttons to push anymore."

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