ENERGY HARVESTING FROM LOW FREQUENCY HARMONICS AND BROADBAND VIBRATIONS

Wireless sensor network (WSN) is rapidly evolving as a useful tool of sensory data
collection for effective management of smart cities. Obviously, a wireless sensor
needs a wireless power supply. An energy harvesting power source not only increases
portability of the wireless devices but also decreases the cost of ownership of wireless
sensors by eliminating the electrical wiring overhead, battery replacement and
disposal costs. Among renewable energy sources, vibration is the most versatile and
generally available source in the target environment of wireless sensor networks.
However, ambient vibrations occur in a low frequency range of few tens of hertz.
Furthermore, in some scenarios spectrum of ambient vibrations varies from source to
source. A conventional resonant harvester responds only near its resonance frequency
and hence fails in harvesting energy from such sources, effectively.