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Pure phase, zinc ferrite (ZnFe 2 O 4 ) nanoparticles were synthesized at lower temperature (80°C) by auto combustion synthesis method. The resulting 'as synthesized' powder was heat treated (HT) at 560°C for 2 h in air atmosphere. As-synthesized particles had sizes *10 nm with spherical shape. Further, these spherically shaped nanoparticles tended to change their morphology to hexagonal plate shape with increasing HT temperature. The band gap of the 'as synthesized' and HT zinc ferite, as determined by using UVVis spectroscopy were found to be 1.92 and 1.86 eV respectively. Gas responses of the ZnFe 2 O 4 nanoparticles were measured by exposing them to ethanol gas vapors. It was found that the zinc ferrite nanoparticles exhibited various sensing responses to ethanol gas at different operating temperature. The best sensitivity was observed at low temperature for 'as synthesized' ferrite nanoparticles than HT zinc ferrite nanoparticles. Sensing material that had smaller particle size and larger specific surface area was observed to have larger gas sensitivity and vice-versa.

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In this paper, we report a wideband energy harvester where mechanical coupling of the cantilever beams in cascaded configuration employed using long and thin spring like structures to couple individual harvesters. The outcomes of designing uni-beam, dual-beam, tri-beam, and quad-beam coupled energy harvesters are compared using COMSOL as well as experimentally. Simulation results indicated that quad-beam coupled energy harvesters had a bandwidth of 10.87 Hz. Physical devices were fabricated in Silicon and tested using PVDF-TrFE piezoelectric material and showed a bandwidth enhancement from 0.7 to 8.9 MHz. The coupling scheme may be extended to larger arrays to increase bandwidth further as per requirements.

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