Design of Acoustic Energy Harvesting Unit Using Piezo-Electric Diaphragm

Abstract

Nowadays, much effort is directed towards solving the energy crisis resulting from depletion of fossil fuel. This has resulted in new approaches in energy industry like developing new sources of energy and harvesting already wasted energy. One of the commonly wasted forms of energy is the vibrational energy existing in noise produced from daily life activities. The goal of this work is to put a design for an Acoustic Energy Harvesting unit that is based on a Piezo-Electric transducer that can convert sound energy of noise into electric energy. The design process followed an experimental approach. It included open circuit as well as closed circuit experiments. The open circuit experiment aimed at finding a good initial guess for incident sound frequency for optimum energy harvesting while the closed circuit experiment aimed at finding the suitable circuit electrical impedance that would maximise energy harvesting at the frequency obtained from the initial guess. The proposed design can harvest power of 0.043 μW, with voltage of 21 mV and current of 2.05 μA, at power harvesting density of 2.8x . These results are achieved at incident sound of sound pressure level (SPL) of 118 dB and frequency of 466.2 Hz.

Recent acoustic energy harvesting methods and mechanisms: A review

“…The relation of frequency (f) and wavelength (λ) with speed (c) is C = f.λ; this speed changes as the properties of the propagation medium change. 31,32 The sound pressure(p) and the intensity (I) is related through particle velocity (v), that is, I = p.v and the power of sound (Ppow) is Ppow = I.A; here, A is the area over which the sound pressure has influence.…”

“…The prototype of an electrostatic generator is explained in detail by Chen et al 42 which consists of two electrodes and one electret plate as in Figure 3. The counter electrode moves towards or away from the electret, and this motion causes the charge generation between them; this charge is drawn by the base electrode, and hence the power generator can produce a maximum voltage amplitude of 8 V when the external heat input increases.…”

“…Figure3. The model of an electrostatic energy generator consisting of electrodes to generate the energy charge with the deflection of electret in between the gap42 …”

The Potential of Cylindrical Piezoelectric Transducers for High-Frequency Acoustic Energy Harvesting

“…When this structure is subjected to mechanical pressure, electrons will be displaced, creating polarization between the negatively charged electron cloud and the positively charged nucleus. This polarization eventually forms an electric field [8,9]. It is necessary to mention that the direction of the applied pressure relative to the material structure is significant.…”