Sensing devices are described. A sensing device includes an inertial sensor, a read-out circuit configured to determine first data indicative of an acceleration of the structure using an output of the inertial sensor, an energy harvester configured to capture energy, and a power management unit. The power management unit comprises a plurality of energy storage components coupled to the energy harvester and a plurality of switches coupled to respective energy storage components of the plurality of energy storage components. The power management unit monitors energy levels stored in the energy storage components, selectively charges the plurality of energy storage components by selectively activating the plurality of switches, and provides power to one or more of the inertial sensor and the read-out circuit based on the monitored energy levels.