TECHNICAL PAPER Simulation, mathematical modeling, fabrication and experimental analysis of piezoelectric acoustic sensor for energy harvesting applications Vasudha Hegde 1 • Siva S. Yellampalli 2 • H. M. Ravikumar 3 Received: 5 July 2019 / Accepted: 21 November 2019 / Published online: 3 December 2019 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2019, corrected publication 2019 Abstract In this paper, an acoustic sensor having ZnO based circular diaphragm sandwiched between two aluminum electrodes as the key element that can find applications in energy harvesting from acoustic sources has been designed, modeled, simulated, fabricated and tested. The ZnO layer is RF sputtered on Silicon substrate and a cavity has been formed by back etching the substrate. The dimensions of the structure are chosen such that the natural frequency of the structure closely matches with that of source frequency to get maximum output voltage due to resonance. The structure is mathematically modeled by Lumped Element Model method and simulated with Finite Element Model method. The experimental results indicate approximately 40 mV output voltage (Open circuit) at 140 db and the natural frequency in the range 11–12 kHz which is in close approximation with the results in mathematical model and simulated structure. 1 Introduction The increase in demand of self-sustaining low power elec- tronic devices has accelerated the demand for energy har- vesting from locally available sources. The micro energy harvesting devices using vibration signal, acoustic signal, etc., can replace the conventional batteries as they have limitation due to limited lifetime and hazardous chemicals. Different methods of energy harvesting along with the concept, methodology of implementation have been published making the relevance of focused research in this field (Choi et al. 2019). Energy harvesting from acoustic sources through piezoelectric transduction can be a good alternative for self-sustaining of very low power devices. The acoustic sources available abundantly in nature make this method more adaptable. The miniaturization of the acoustic sensors makes it portable and compact as they can be easily embedded inside the application. Their natural frequency can be matched with different frequency ranges to get maximum displacement due to resonance. This implementation is supported by very well-established MEMS fabrication processes (Choi et al. 2019). Energy harvesting by acoustic or vibration sources can be efficiently done by piezoelectric materials because of their scalability, repeatability and ease of integration with CMOs technology. Scaling down of the devices is pre- ferred (Li et al. 2016). Further, the selection of the suitable material for fabri- cation is done by Ash by approach with the value of fig- ure of merit (Pratap and Arunkumar 2007). For biomedical applications and also for the applications having environ- mental concerns, piezoelectric materials like ZnO, AlN and lead free materials are preferred over Lead Zirconate Titanate (PZT) (Li et al. 2016). This selection also justifies the clean room compatibility during fabrication. The range of the frequency from the day to day appli- cation is as listed in Table 1. From the table it is clear that The original version of this article was revised due to a retrospective open access cancellation. & Vasudha Hegde vasudha.hegde@nmit.ac.in Siva S. Yellampalli siva.yellampalli@gmail.com H. M. Ravikumar hmrgama@gmail.com 1 Electrical and Electronics Engineering, Nitte Meenakshi Institute of Technology, Bangalore, Karnataka, India 2 School of Engineering and Applied Sciences, SRM University, Amaravati, Andhra Pradesh, India 3 Electrical Power and Control Engineering, School of Electrical Engineering and Computing, Adama University of Science and Technology, Adama, Ethiopia 123 Microsystem Technologies (2020) 26:1613–1623 https://doi.org/10.1007/s00542-019-04702-x