Long Battery Life to Benefit Field Sensors

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Troops are now able to gather intelligence without having to venture into a potential combat zone themselves. They also have the reassurance that they would be moving into hazardous areas far less often to replace “battery-dead” sensors. Battery lifetimes can now be extended by using sensors that only wake up to record a triggering event, such as a sound, or to periodically (instead of continuously) monitor a battlefield or other concern, said the US Agency DARPA.

DARPA’s Near Zero Power RF and Sensor Operations (N-ZERO) program, which concluded in May 2020 was designed to find  ways around the lifetime limitations of IoT battery power so that sensors could be deployed in the field to detect events like vibration, light, sound, or other battlefield signals without having to be frequently replaced.

“The N-ZERO program established asleep-yet-continuously-alert sensing capabilities for untethered, unattended systems that are triggered by specific physical or radio frequency [RF] signatures,” said Benjamin Griffin, program manager in DARPA’s Microsystems Technology Office. “Sensor lifetimes that are on the order of years will enable cost-effective and safe deployment of sensing technologies in areas lacking fixed-energy infrastructure.”

What Griffin acknowledged for now was that RF, acoustic, and infrared (IR) wake-up capabilities were the most successful sensing systems developed by the N-ZERO program. These near-zero-power sensors transmit radio signals to communicate (RF), measure sound levels (acoustic), and detect IR (thermal) radiation.

An estimated battery lifetime extension was achieved from four weeks to up to four years, based on a coin-cell battery. Despite these successes, the battery lifetimes of sensors tested in the N-ZERO initiative are still limited by processing and communications of confirmed events and/or ultimately by the self-discharge of the battery itself.

One move in a positive direction was the development of an ultra-low-power Arm processor. DARPA said that lower processing options that dramatically increase battery life (like Arm) can cut costs that get incurred when sensors must be replaced frequently because their batteries fail, according to eetasia.com.