Lead-Zirconate-Titanate Acoustic Energy Harvester Equipped with Sound-Collecting Helmholtz Resonator. - Tomohiro Matsuda; Kazuki Tomii; Satoshi Iizumi; Shungo Tomioka; Shu Kimura; Kyohei Tsujimoto; Yusuke Uchida; Saori Hagiwara; Shuntaro Miyake; Yasushiro Nishioka (IEICE Trans. Electron., 2013)