A look inside the Wii remotes

There’s been a lot of talk recently about the dangers of the Wii remotes caused by the wrists straps breaking during game play. Nintendo answered by replacing the straps with a heavier corded strap. But what makes these remotes work? What makes them different from the normal remotes on most other gaming consoles? For starters, they use the same technology that activates a vehicle air bag, by using tiny devices called MEMS, micro-electro-mechanical systems, that can accurately sense three axes of acceleration: up and down, left to right, and forward and backward. Using an image sensor and tiny light emitting diodes in a “sensor bar” the remotes communicate with the Wii console via Bluetooth technology and infrared.

The principles of MEMS technology are based upon the mechanical properties of the silicon — stronger than steel but only a third of the weight — to create moving structures. Combined with microelectronics, signals generated by the moving structures give perception and control capabilities to create a new generation of sensors.
Typically a MEMS accelerometer consists of interlocking fingers that are alternately moving and fixed. Acceleration is sensed by measuring the capacitance of the structure, which varies in proportion to changes in acceleration. The elements can be arranged like combs to make a linear accelerometer, as is the type used in airbags, or like the spokes of a wheel to make a rotational accelerometer.

While conventional microelectronics development focuses on incremental improvements of a well-established technology, MEMS challenge the way designers work, compelling them to think three dimensionally and to acquire a unique blend of multi-disciplinary skills combining electrical, semiconductor, and mechanical design.

It doesn’t matter if you like the gaming system or not, this is some pretty cool stuff. Might make you think twice before letting Junior take the Wii along on a road trip. Check out the STMicroelectronics website for more info on MEMS technology.