ARLINGTON, Va., 5 June 2012. Infantry technology experts at the U.S. Defense Advanced Research Projects Agency (DARPA) needed a small, low-power accelerometer second generation of DARPA's Blast Gauge to protect U.S. Armed Forces personnel. They found their solution from Analog Devices Inc. in Norwood, Mass.
Blast Gauge is a soldier-worn sensor developed at Rochester Institute of Technology in Rochester, N.Y., that serves as a screening tool for medical personnel performing triage on infantrymen exposed to a blast and provides detailed data for researchers looking into the causes of traumatic brain injury (TBI).
The initial generation of the Blast Gauge, commercialized by BlackBox Biometrics (B3) Inc. in Rochester, N.Y., used the ADXL345 MEMS accelerometer from Analog Devices. It has been deployed for a year on thousands of U.S. soldiers in Afghanistan, Analog Devices officials say.
Now the Analog Devices ADXL362 low-power accelerometer based on micro-electro-mechanical systems (MEMS) technology is planned for the second generation of DARPA's Blast Gauge. "The ADXL362 will significantly extend battery life in these sealed devices which utilize a non-rechargeable battery," says David Borkholder, chief technology officer of BlackBox Biometrics.
Analog Devices is introducing the ADXL362 MEMS accelerometer for applications that require battery life expectancy of months or years, and where battery replacement can be impractical or dangerous to the equipment or operator.
The ADXL362 is a three-axis digital MEMS accelerometer that operates on power of as little as at 300 nano-amps in motion-sensing wake-up mode, consuming 60 percent less current than the closest competing sensor in the same mode, Analog Devices officials claim.
In full measurement mode, the ADXL362 uses 2 micro-amps at a 100 Hz data rate, using 80 percent less power than competing MEMS accelerometers operating at the same frequency.
Systems designers also can use the ADXL362 as part of an intelligent, continuously operational, motion-activated switch, Analog Devices officials say. Equipped with an awake status output pin, the motion sensor can trigger a switch that turns on system functions, bypassing the processor, to reduce system power further.
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The ADXL362 also integrates an enhanced, sample activity detection function that distinguishes between different kinds of motion. This eliminates false positives and prevents the sensor from turning the system on unnecessarily and costing additional battery life, company officials say.
The ADXL362 MEMS accelerometer embeds a deep internal FIFO memory block that enables system designers to record data and stream long data sets, reducing processor load and saving additional system power. The device also has two low-noise modes that enable the user to cut the device's noise in half at the expense of a few micro-amps.
The new MEMS accelerometer also has a built-in micro-power temperature sensor the ability to synchronize the sampling time to an external trigger. The ADXL362 natively provides acceleration data with 12-bit resolution, as well as 8-bit formatted data for efficient single-byte transfers when a lower resolution is sufficient.
The accelerometer has measurement ranges of plus-or-minus 2 g, plus-or-minus 4 g, and plus-or-minus 8 g, with a resolution of 1 mg/LSB on the plus-or-minus 2 g range.