Infrastructural internet-of-things using quasi-self-powered structural health monitoring sensors

Current structural health monitoring (SHM) techniques focus primarily on maintenance and thus lack the ability and specificity to provide actionable information in the event of extreme/rare events or disasters like hurricanes or earthquakes. While battery-powered wireless sensors can evaluate the condition of the structure at a given instant of time, long-term operation requirements force these devices to use long-sleep cycles and hence are unable to fully quantify the extent of the damage. On the other hand, self-powered sensors can continuously monitor the structural condition without the need for any maintenance; however, the scarcity of power that can be harvested limits the range at which the sensors could be wirelessly interrogated. In this paper, we propose a quasi-self-powered sensor that combines the benefits of self-powered sensing with the benefits of battery-powered wireless transmission. By optimizing both the functionalities, a complete sensor system can be designed that can continuously operate between the structure's maintenance life-cycles and can be wirelessly interrogated at distances that obviates the need for taking the structure out-of-service. We present case studies of environments where prototypes of the quasi-self-powered sensors have been deployed, including on the Mackinac Bridge in northern Michigan.