'Asleep-yet-aware' electronics could revolutionise remote wireless sensors
19 April 2015
DARPA is seeking to develop near-zero-power technologies that could operate reliably for years and eventually benefit the growing global network of Internet-enabled devices.
Military sensors today rely on 'active' electronics to detect vibration, light, sound or other signals. That means they constantly consume power, with much of that power and time spent processing what often turns out to be irrelevant data.
This power consumption limits sensors’ useful lifetimes to a few weeks or months when operating from state-of-the-art batteries, and has slowed the development of new sensor technologies and capabilities. Moreover, the chronic need to redeploy power-depleted sensors is not only costly and time-consuming but also increases combatants' exposure to danger.
The US Defense Advanced Research Projects Agency (DARPA) has inaugurated a new programme called Near Zero Power RF and Sensor Operations (N-ZERO) which seeks to overcome the power limitations of persistent sensing by developing wireless, event-driven sensing capabilities that would allow physical, electromagnetic and other sensors to remain dormant—effectively asleep yet aware—until an event of interest awakens them.
To achieve these goals, the programme intends to develop underlying technologies continuously and passively to monitor the environment and activate an electronic circuit only upon detection of a specific signature, such as the presence of a particular vehicle type or radio communications protocol. N-ZERO seeks to exploit the energy in signal signatures to detect and recognise attention-worthy events while rejecting noise and interference.
“It is the waiting for a specific event or activity that constrains mission life and drains the battery energy of these essential electronics,” says DARPA's programme manager, Troy Olsson. “By cutting reliance on active power and enhancing battery life, N-ZERO aims to enable wireless, ubiquitous sensing that is energy efficient and safer for the combatant.
"Our goal is to use the right signal itself to wake up the sensor, which would improve sensors’ effectiveness and combatants’ situational awareness by drastically reducing false alarms.”
Through N-ZERO, DARPA wants to make sensors phenomenally more efficient in how they draw power when not actually sensing something of interest. The goal is to use less than 10 nanowatts during the sensor’s asleep-yet-aware phase — an energy draw-down roughly equivalent to the self-discharge (battery discharge during storage) of a typical watch battery, and at least 1,000 times lower than state-of-the-art sensors.
Specifically, N-ZERO seeks to extend unattended sensor lifetime from weeks to years, cut costs of maintenance and the need for redeployments. Alternatively, N-ZERO could also reduce battery size for a typical ground-based sensor by a factor of 20 or more while still keeping its current operational lifetime.
DARPA is currently seeking proposals for N-ZERO. Further details can be found here.