Energy Harvesting in IoT Devices

In current wireless sensor networks, devcies are mostly powered by batteries.
Using batteries is inconvenient (difficult to replace after sensors have been deployed) and is not environment friendly (polutions and difficult to dispose).

Therefore, in IoT systems, it is expected that sensors power themselves by harvesting energies from the environment.

Due to the types of energy available and the environment the sensors are in, different energy harvesting technologies have to be used.

The ultimate goal of energy harvesting is to obtain electrical energy to charge batteries.

Mechanical energies can come from motion and vibration. Generators are frequently used to convert motion to electrical energy. Vibration can be converted to electrical energy using transducers based on variable capacitors.

Lights can be converted to electrical energy via something called "photovoltaic effect" on semiconductor materials.

Electromagnetic energy (radio frequency - RF) can be harvested using antennas, amplifiers and other electronic circuits.