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In this letter the authors report experimental results on an optimized small scale piezoelectric windmill, which can solve the problems associated with autonomous sensor networks in outdoor, remote or inaccessible locations. The whole structure of the windmill is made of plastic, and it utilizes 18 piezoelectric bimorphs which makes this design extremely cost effective. The windmill was tested at average wind speed of 10miles∕h and it provided 5mW continuous power. The threshold wind speed for the windmill was found to be of the order of 5.4miles∕h. Further, the authors present analysis on two other windmill structures which illustrate the design parameters required for small scale windmill.

This study reports the experimental and analytical results on a piezoelectric cymbal with 29 mm diameter and 1 mm thickness operating under force of 70 N in the frequency range of 10–200 Hz. It was found that the generated power increases with the frequency and around 100 mW can be harvested at frequency of 200 Hz across a 200 kΩ resistor. Power generation from the cymbal transducer was modeled by using the theory developed for the Belleville spring. The calculated results were found to be in good agreement with the experimental results. The results indicate that the metal–ceramic composite transducer “CYMBAL” is the most promising structure for harvesting the electric energy from automobile engine vibrations. The metal cap enhances the endurance of the ceramic to sustain high loads along with stress amplification.

Magnetoelectric particulate composites with varying ferrite content (3–20mol%) were synthesized in the system Pb(Zr0.52Ti0.48)O3 (PZT)–Ni0.8Zn0.2Fe2O4 (NZF) and it was found that 0.8PZT-0.2NZF composite material exhibited high response of the order of 450mV∕cmOe at the low frequency of 1kHz with 600Oe dc bias. This is one of the highest magnitudes reported for the sintered particulate composite materials. This material was used to fabricate a magnetic field sensor which utilizes the piezoelectric transformer structure with ring/dot electrode pattern. The size of the magnetic field sensor was ϕ20×1.5mm2. The sensor was characterized for the changes in the output voltage and resonance frequency shift under constant current condition. A dramatic change in the magnitude of the output voltage and frequency shift was observed on application of the magnetic field. The sensor design presented in this letter clearly shows the possibility of fabricating an extremely cost-effective magnetometer.

In this letter the authors present the experimental data illustrating the working mechanism of the high sensitivity differential magnetic field sensor. Further, the authors report for the data showing the possibility for realizing a voltage controlled magnetic field. The sensor works on the following principle. A constant voltage is applied to the ring section of the sensor at the resonance frequency which induces magnetic field in the dot section. If an external magnetic object is brought in the vicinity of the dot section, then the resulting differential magnetic field induces change in the voltage gain due to magnetoelectric effect.