This paper reports the design of an electromagnetic vibration energy harvester that doubles the magnitude of output power generated by the prior four-bar magnet configuration. This enhancement was achieved with minor increase in volume by 23% and mass by 30%. The new ‘double cell’ design utilizes an additional pair of magnets to create a secondary air gap, or cell, for a second coil to vibrate within. To further reduce the dimensions of the device, two coils were attached to one common cantilever beam. These unique features lead to improvements of 66% in output power per unit volume (power density) and 27% increase in output power per unit volume and mass (specific power density), from 0.1 to 0.17 mW cm−3 and 0.41 to 0.51 mW cm−3 kg−1 respectively. Using the ANSYS multiphysics analysis, it was determined that for the double cell harvester, adding one additional pair of magnets created a small magnetic gradient between air gaps of 0.001 T which is insignificant in terms of electromagnetic damping. An analytical model was developed to optimize the magnitude of transformation factor and magnetic field gradient within the gap.

The demand for efficient small-scale wind harvester is continually increasing in order to meet the local power needs for applications ranging from wireless sensor networks to charging of mobile devices. The efficiency of wind turbines is dependent upon several structural variables including frictional contacts. In order to overcome the problem of gearing and losses in mechanical contacts, we propose here a novel small-scale windmill design that utilizes magnetic attractive and repulsive force to create mechanical oscillation in piezoelectric bimorphs which is then converted into electric charge through direct piezoelectric effect. This contact-less wind turbine has several advantages including operation at much lower wind speeds and longer life span. The prototype was fabricated as a vertical-axis wind turbine featuring a modular Sarvonius rotor. Characterization was performed by utilizing several configurations for this modular rotor. Output power magnitude for steady-state operation in wind speeds of 2 -10 mph was used to compare the performance of various configurations.

This study reports the design, fabrication, and implementation of a horizontal-axis, small-scale modular wind turbine termed as "small-scale wind energy portable turbine (SWEPT)". Portability, efficient operation at low wind speeds, and cost-effectiveness were the primary goals of SWEPT. The fabrication and component design for SWEPT are provided along with the modifications that can provide improvement in performance. A comparative analysis is presented with the prototype reported in literature. The results show that current version of SWEPT leads to 150% increase in output power. It was found that SWEPT can generate 160 mW power at rated wind speed of 7 mph and 500mW power at wind speeds above 10 mph with a cut-in wind speed of 3.8 mph. Furthermore, the prototype was subjected to field testing in which the average output was measured to be 40 mW despite the average wind distribution being centered around 3 mph.

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We report nanotesla sensitivity in Metglas/piezoelectric/carbon fiber/piezoelectric laminates with active tip mass operating in the vicinity of second bending mode. The peak magnetoelectric response for the laminate with an active tip mass (1 g) in longitudinal-transversal mode under Hdc=8 Oe and Hac=1 Oe was found to be ∼1.08 V/cm Oe at 43 Hz (first bending mode) and ∼19 V/cm Oe at 511 Hz (second bending mode). At the standard 1 kHz frequency, the maximum resolution of 5 nT was measured under Hac=0.5 Oe.