MEMS-based near-zero power infrared wireless sensor node

This paper reports on the first demonstration of an infrared (IR) wireless sensor node (WSN) with near-zero standby power consumption. The prototype presented here employs a plasmonically-enhanced micromechanical photoswitch (PMP) that exploits the energy contained in the impinging IR spectral band of interest itself, to perform passive sensing and digitizing functions. The palm-sized IR WSN demonstrated in this work comprises a vacuum-packaged PMP (IR power threshold ∼284 nW, lithographically-defined IR absorptance: ∼89% at 4.6 μm, 0.75 μm bandwidth) connected to a CMOS load-switch which wakes up a coin battery-powered sub 1-GHz wireless microcontroller to transmit data when the IR signal of interest is detected. The standby power consumption for the IR WSN was measured to be just ∼2.6 nW: a >1900X improvement over state-of-the-art pyroelectric IR WSNs, while offering integrated spectral-selectivity. This work represents the first demonstration of an OFF-but-alert WSN that awakens only in the presence of a signal of interest, resulting in near-unlimited battery-life when deployed to detect infrequent but time-critical events.