A Review of Vibration Based Wide-Band Electromagnetic Energy Harvesters
Vibration based electromagnetic energy harvesters (VEMEHs) for powering wireless sensor nodes (WSNs) and low power devices has got enormous research interests as alternative source of power. One of the prime limitations to the application of these harvesters as a replacement to battery systems is their dependency on the limited range of operating frequencies. This paper highlights the current advancements in the area of wide-band VEMEHs. All such VEMEHs have been studied and reported based on their range of operating frequencies, frequency bandwidth, overall volume, output voltage, the value of available output power, power density and the level of vibrations these harvesters are subjected to. Moreover the reported VEMEHs are categorized on the basis of their operating mechanism i.e either resonant or non-resonant. The main focus over here is the operating range of frequencies and the frequency bandwidth where the harvester is capable of producing adequate amount of output power which could be used for operating remote WSNs. The reported VEMEHs include harvesters with a minute volume of 0.032 cm3 to as large as approx 1600 cm3. When compared on the basis of output voltage, the reported VEMEHs could produce output voltage from 0.13 mV to as high as 5700 mV. Similarly the reported VEMEHs are generating output power from 0.00096 μW to 74000 μW. The reported VEMEHs are having power densities in the range of 0.50 x 10-6 μW/ cm3 to1073 μW/ cm3. The power per acceleration of the reported VEMEHs is in the range of 16.012 x 10 -6 μW/g to 129824 μW/g. Moreover the reported VEMEHs are having power density per acceleration in the range of 0.500 x 10-6 μW/g.cm3 to 1877 μW/g.cm3. Based on the overall device’s size and resultant output power, a 1 cm³ harvester having an average power output of 0.75 μW to a harvester of 68.96 cm³ with a peak output power of 74 mW have been reported in this literature. Comparison has been made on the basis of operating frequency range, frequency bandwidth, device size, output power, acceleration of operation, power per acceleration and power densities of the reported wide-band electromagnetic energy harvesters (EMEHs).