A new microelectromechanical systems (MEMS) sensor system offers 1,000 times more sensitivity and far greater dynamic range than conventional, high-volume accelerometers.
The inertial sensor system, developed by engineers at Hewlett-Packard, could open up a whole new category of applications for design engineers who need greater sensor sensitivity but can't afford high-cost mechanical sensing systems. HP engineers foresee the new accelerometer being used in earthquake monitoring, geophysical mapping, mine exploration and bridge vibration monitoring.
"The number of applications for these sensing systems is enormous," says Rich Duncombe, strategist for Hewlett-Packard's Technology Development Organization.
HP engineers say they've been able to increase sensitivity by a factor of 1,000 while simultaneously boosting dynamic range because they departed from conventional accelerometer design by employing a larger "proof mass." The silicon proof mass, which is critical to the device's ability to sense acceleration, is limited in its sensitivity in some cases by the presence of thermo-mechanical noise. By increasing the size of the proof mass a thousand-fold, however, HP engineers were able to minimize the noise and maximize sensitivity.
"Most people have a microgram of mass in there," says Peter Hartwell, senior researcher and inventor in HP Labs. "We're closer to a milligram." The overall package size of the accelerometer, however, is still just 5 mm square by 2 mm thick, Hartwell says.
At the same time, HP engineers employed a unique electrode arrangement that enables their accelerometer to have a broader dynamic range while still achieving the 1,000X sensitivity improvement.
The availability of the new sensor could provide a big advantage to engineers who use accelerometers to measure vibrations in bridges, as well as for oil and gas exploration and earthquake monitoring. Whereas such applications typically use costly mechanical accelerometers, HP's new devices are expected to be in the cost range of other MEMS devices. Watch a video of HP's ultra-sensitive accelerometer athttp://designnews.hotims.com/27742-530.