MEMS, or microelectromechanical systems, as the name implies, are systems built through a combination of mechanical and electrical engineering. They can include some moving parts, or none at all, and they can range from relatively simple to extremely complex. Until 2006, they were largely unheard of outside of narrow markets such as airbags and inkjet cartridges. That was the year Nintendo introduced the Wii with an accelerometer built into the controller. The MEMS market exploded after that, expanding out in every direction, including smart phones and other portable devices.
MEMS chips today are used in everything from microvalves, micromirrors, pressure sensors for microphones, to labs-on-a-chip, which can test a drop of blood, for example, within minutes instead of hours. Also included in this category are inertial sensors, such as gyroscopes and accelerometers, both of which are present in almost every mobile device to detect motion. The combination of MEMS devices is how Google’s Waze, a popular peer-to-peer GPS application, can tell if you’re stuck in traffic or moving, how fast you’re moving, and when you’re likely to arrive at your destination given current traffic conditions. There also are compasses, vibration sensors, as well as capacitive touch sensors for security.
Billions of these tiny units are sold each year, with no end in sight for increases in volume. But every MEMS maker complains that ASPs have fallen faster than sales volumes have increased. Downward price pressure has dominated this market for nearly a decade, since smartphones began replacing feature phones.
MEMs chips typically fall into four categories:
• Capacitive. This technology can be used to detect anything that is conductive. They can be found in touchscreens and fingerprint sensors.
• Gyroscopic. These devices use an oscillation component to detect acceleration in any direction.
• Piezoelectric. These thin-film-based devices are still in the early rollout phase, but are expected to be used in a variety of applications, including energy harvesting. They produce electrical signals in response to mechanical stress.
• Laser-based. These devices also are in the developmental phase. The basic premise is that they can fine-tune lasers for a variety of purposes, from advanced automotive headlights to acousto-optic filters.