Theoretical analysis of piezoceramic ultrasonic energy harvester applicable in biomedical implanted devices

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Abstract In this article, we theoretically analyze the one-dimensional model of a piezoceramic energy harvester that uses piezoelectric transduction in the 3-3 mode to convert ultrasonic pressure waves into electrical energy. Our approach to this problem is new because we did not use impedance approach which is a common method in many other articles. Nonetheless, our solution accounts for loss of acoustic environment. Our goal here is to extract maximum power from output load. Based on our simulations, the frequencies that the acoustic strength peaks are as same as frequencies that the pressure at receiver side peaks, and between these frequencies, the resonance occurs at a frequency that the pressure at the receiver side has a maximum peak. We propose two boundary conditions for radiating acoustical waves. In this article for a square shape transducer with a thickness of 2.1 mm and length of 1.46 cm, the resistive output load gave the most power, in which its value for free-fixed and free-free boundary conditions are 13.75 W and 17.37 W respectively, and at output resistances of 8.51 Ω and 13.11 Ω respectively. The required acoustic strengths to produce these powers for free-fixed and free-free boundary conditions are 424.944 × 1 0 7 m 3 s 2 424.944\times 1{0}^{7}\frac{{{\rm{m}}}^{3}}{{{\rm{s}}}^{2}} and 129.977 × 1 0 8 m 3 s 2 129.977\times 1{0}^{8}\frac{{{\rm{m}}}^{3}}{{{\rm{s}}}^{2}} . The resonance frequencies are 9.13545 MHz and 14.3617 MHz respectively, and the pressures at receiver side in the distance of 5 cm from transmitter transducer are 623.968 MPa and 1382.39 MPa respectively.