Published in August 2016
Yoonmyung Lee, David Blaauw, and Dennis Sylvester
Wireless sensor nodes (WSNs) are essential elements for today's structural health monitoring (SHM). As the design technology for WSNs evolves, there have been continuous efforts to address challenges for WSNs such as short lifetime, high power consumption, and bulky volume. Recent trends show energy harvesting becoming a popular solution for extending the lifetime of WSNs; even implementing energy-autonomous systems is an option. Smaller WSN form factors have been developed for volume-limited applications and sensor nodes as small as a few mm3 were created with custom-designed integrated circuits (ICs). Custom IC-based sensor nodes enable energy-efficient implementation of WSNs for SHM. Ultralow power circuits with operation power on the order of nanowatts are introduced in this paper. Ultralow power energy harvesters, timers, wakeup receivers, sensing modalities, and microprocessors are expected to significantly extend sensor node lifetime or achieve sensor node operation with ambient energy harvesting.