Zero-power sensors with near-zero-power wakeup switches for reliable sensor platforms

The near zero-power sensor node solution is presented with piezoelectric sensors and DC tunable threshold electrostatic switches. A sensor suite measuring acceleration, rotation, and magnetic field based on PZT lateral bimorphs is used with NEMS switches for the detection of a desired signal pattern and generating a wake up trigger. The sensors are capable of detecting physical signals from 5 Hz to 1.5 kHz, with sourcing load capacitances as high as 200 pF. The sensor sensitivities achieved are: 0.1 V/g for the accelerometer, 31 mV/Gauss for the magnetic field, and 0.31 mV/(°/s) for rotation. NEMS switches, with threshold voltages in the mV to 15V range, can combine multiple sensor outputs through multi-gate actuation to detect desired event specific features. Using the sensors, we demonstrate the detection of a portable electrical generator in its different operational modes (On/Off state and the Eco mode).