IR Sensor Consumes No Power till Specific Wake-up Scene Detected

IEEE Spectrum, DARPA: Northeastern University, Boston, MA researchers publish Nature Photonics paper "Zero-power infrared digitizers based on plasmonically enhanced micromechanical photoswitches" by Zhenyun Qian, Sungho Kang, Vageeswar Rajaram, Cristian Cassella, Nicol McGruer & Matteo Rinaldi.

"It consists of a tiny, micromechanical switch that controls the connection to a battery. Only when the switch is activated by the infrared radiation does it move to close the gap between itself and its battery, triggering the wake-up signal.

The switch contacts are supported by beams made out of a two-material stack. When the temperature of this structure increases, one material expands more than the other, and therefore the beams bend,” Rinaldi explains. That bending allows the switch to make contact with the battery and spit out a signal."

“What is really interesting about the Northeastern IR sensor technology is that, unlike conventional sensors, it consumes zero stand-by power when the IR wavelengths to be detected are not present,” said Troy Olsson, manager of the N-ZERO Program in DARPA’s Microsystems Technology Office. “When those IR wavelengths are present and impinge on the Northeastern team’s IR sensor, the energy from the IR source heats the sensing elements which, in turn, causes physical movement of key sensor components. These motions result in the mechanical closing of otherwise open circuit elements, thereby leading to signals that the target IR signature has been detected.”

“The technology features multiple sensing elements—each tuned to absorb a specific IR wavelength,” Olsson noted. “Together, these combine into complex logic circuits capable of analyzing IR spectrums, which opens the way for these sensors to not only detect IR energy in the environment but to specify if that energy derives from a fire, vehicle, person or some other IR source.”