Piezoelectric Energy Harvesting Using a Novel Cymbal Transducer Design G. Yesner, M. Kuciej, and A. Safari Department of Materials Science and Engineering Rutgers University Piscataway, NJ, USA A. Jasim, H. Wang, and A. Maher Center for Advanced Infrastructure and Transportation Rutgers University Piscataway, NJ, USA Abstract— A novel bridge transducer based on the cymbal design has been developed for energy harvesting from impact loading by vehicle-induced deformations in pavement. The bridge transducer consists of a 2 mm thick 32x32 mm square soft PZT ceramic and hardened steel end caps. A novel electrode design is used to polarize the piezoelectric ceramic along its length, effectively utilizing d 33 mode for enhanced energy generation. A prototype module with 64 bridge transducers were fabricated and loaded repeatedly to simulate vehicle traffic on a highway. When compared to the conventional transducer design, horizontal poling increases energy and voltage considerably. Each loading of the prototype transducer module generates 0.83 mJ of energy. Loading under simulated traffic conditions at 5 Hz generated 2.1 mW at a resistive load of 400 kOhm. Keywords—Piezoelectric energy harvesting; pavement energy harvesting; cymbal transducer; surface poling I. INTRODUCTION Piezoelectric energy harvesting devices exploit environmental energy sources to convert wasted mechanical energy into useable electrical energy. Mechanical energy from ambient vibrations can be harvested using a piezoelectric bimorph cantilever tuned to the frequency of the vibration. Equipment or machinery with a known, constant vibrational frequency is an excellent source for a tuned cantilever energy harvester and has been used to power sensors and wireless nodes [1]. Broadband energy harvesting devices have multiple resonant frequencies and can operate over a wider range of frequencies than tuned cantilevers. Many designs for broadband piezoelectric energy harvesting devices have been used such as a cantilever with multiple resonant frequencies [2]. These devices can utilize a range of vibrational frequencies but have limited performance for low frequency and non- resonant sources such as cyclic impacts or intermittent pulses. The cymbal transducer has conical end caps that amplify the applied force and converts the stress to compression and tension in piezoelectric ceramic [3]. The cymbal uses a combination of d 33 and d 31 piezoelectric coefficients for the applied compression and tension, respectively. The square or rectangular version of the cymbal is called a bridge transducer due to its shape. Cymbal transducers have been studied for use in vibrational energy harvesting under cyclical loading and high stress [4][5]. Low frequency and non-vibrational energy harvesting has been accomplished using composite transducers like the cymbal or THUNDER [6]. The THUNDER transducer was used for piezoelectric energy harvesting from walking [7]. A transducer was placed in the heel of a shoe and energy was generated from the heel strike with each step while the user walked. A source of unused mechanical energy is vehicle induced loading in pavement [8]. Energy harvesting from pavement utilizes the elastic energy from the stress and strain resulting from vehicle loading on the pavement, which would normally converted to heat. A study by Zhao et al compared the performance of different types piezoelectric transducers for pavement energy harvesting [9]. It was found that matching the stiffness of the transducer to the asphalt pavement was necessary to facilitate the transfer of energy to the transducer. If the transducer embedded in the pavement is too stiff, as in the case of a monolithic ceramic or multilayer actuator, the strain energy is not transferred to the transducer but into the surrounding and underlying pavement instead. Composite transducers like THUNDER and macrofiber composite have low stiffness so strain in the pavement will only result in a small stress induced in the transducer and minimal energy can be generated. The cymbal transducer can be matched to the stiffness of the asphalt pavement by the shape and material of the metal end cap [10][11]. In this work, a novel bridge transducer utilizing horizontal poling for enhanced energy generation is developed and tested for a pavement energy harvesting application using simulated vehicle impact loading. Figure 1. PZT-5X ceramic with repeating surface electrodes. 978-1-5090-1871-0/16/$31.00 ©2016 IEEE