Elsevier

Nano Energy

Volume 13, April 2015, Pages 174-181
Nano Energy

Rapid communication
Powerful curved piezoelectric generator for wearable applications

Highlights

We present the flexible piezoelectric generator with a curved structure favorable for wearable applications, generating high output power.

Electrical output reaches ~120 V of peak output voltage and ~700 µA of peak output current, which can light up 476 LEDs and operates the battery management circuit which continuously supplies a constant output voltage of 3.3 V.

We demonstrate the possibility that the generator can be used in shoes, watches, and clothes as a power source, and as a sensor for cardiac impulse and human breathing.

Abstract

With the widespread use of wearable electronics, the flexible piezoelectric energy harvesting devices have been extensively studied to efficiently convert the physical motion of the human body into electrical energy. The major obstacles for realizing a flexible piezoelectric generator include the insufficient output power generation and the poor efficiency at the low-frequency regime. Here, we demonstrate a curved piezoelectric generator favorable for wearable applications, generating a high output power. The curved structure plays a key role to improve the power generation, by effectively distributing the applied force across the piezoelectric layer, as well as to allow operation at the low frequency vibration range. Accordingly, this generator produces ~120 V of peak output voltage and ~700 µA of peak output current during a cycle. Furthermore, our generator can operate at low frequencies below 50 Hz, generating ~55 V of output voltage and 250 µA of output current at 35 Hz, and it even works at frequencies as low as 1 Hz. With this generator, we successfully lit up 476 commercial LED bulbs. In addition, we experimentally demonstrate the possibility that the generator can be used in shoes, watches, and clothes as a power source. Our results will provide a framework to enhance the output power of conventional piezoelectric generators, and open a new avenue for realization of self-powered systems, such as wearable electronic devices.

Keywords

Energy harvester
Piezoelectric
Wearable

Choose an option to locate/access this article:

Check if you have access through your login credentials or your institution.

Vitae

Dr. Woo-Suk Jung received the Ph.D. degrees in Department of Electronics from Hoseo Univ. Korea in 2009. Continuously, he has been a post-doctoral research fellow with Electronic Materials Center, Korea Institute of Science and Technology, Seoul, Korea. From 2010 to 2011, he has been a post-doctoral research fellow with the Department of Mechanical Engineering, University of Toronto. Now his current research interests are development of energy harvesting devices and piezoelectric actuators including design, simulation, and their related circuits.

Dr. Min-Jae Lee received the B.S. degree in the Department of Mechanical System Design Engineering from Seoul National University of Science and Technology, Korea, in 2014. His research interests include the simulation and fabrication of micro- and macro-energy harvesting devices with piezoelectric and triboelectric materials.

Dr. Min-Gyu Kang received the B.S. degree in Department of Electronic Materials Engineering from University of Suwon, Korea, in 2008, and Ph.D. degree in Department of Material Science and Engineering from Korea University, Korea, in 2014. He is currently a post-doctoral research fellow with the Department of Mechanical Engineering, Virginia Tech. His current research interests are in the field of ferroelectric and piezoelectric thin films, and their application.

Hi Gyu Moon is studying for his M.S. in the Department of Materials Science and Engineering of Yonsei University. His research interests include the fabrication of metal oxide gas sensors and their electrical characteristics.

Dr. Seok-Jin Yoon received his Ph.D. from his Ph.D. from the Department of Electrical Engineering of Yonsei University in 1992. Now he is a principal research scientist and the head of the Smart Electronic Materials Laboratory in KIST. His research interests include piezoelectric materials, ultrasonic piezoelectric actuators, and gas sensors.

Dr. Seung-Hyub Baek received his B.S. degree from Seoul National University, Seoul, Korea in 2004, and his M.S. and Ph.D. degrees from the University of Wisconsin-Madison, USA in 2007 and 2010, respectively. He served for his postdoctoral research work at the University of Wisconsin-Madison. Since 2011, he has worked for KIST as a senior research scientist. His research interests include piezoelectric MEMS, ferroelectrics, multiferroics, oxide interfacial phenomenon, and thermoelectricity.

Dr. Chong-Yun Kang received his Ph.D. from the Department of Electrical Engineering of Yonsei University in 2000. Now he is a Principal Research Scientist in KIST from 2000 and a professor of KU-KIST Graduate School of Converging Science and Technology in Korea University from 2012. His research interests include smart materials and devices, expecially, piezoelectric energy harvesting and actuators, electrocaloric effect materials, and nanostructured oxide semiconductor gas sensors.