Nanogenerators for self-powered micro/nano-systems

Time: 3:00-4:30 pm

Date: Nov. 09 , 2010
Location: 同济大学逸夫楼二楼演讲厅
Reporter: Zhong Lin Wang(School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta USA)

Developing wireless nanodevices and nanosystems is of critical importance for sensing, medical science, environmental/infrastructure monitoring, defense technology and even personal electronics. It is highly desirable for wireless devices to be self-powered without using battery. This is a new initiative in today’s energy research for mico/nano-systems in searching for sustainable self-sufficient power sources [1]. It is essential to explore innovative nanotechnologies for converting mechanical energy, vibration energy, and hydraulic energy into electric energy that will be used to power nanodevices. We have invented an innovative approach for converting nano-scale mechanical energy into electric energy by piezoelectric zinc oxide nanowire arrays [2]. The operation mechanism of the nanogenerator relies on the piezoelectric potential created by an external strain; a dynamic straining of the nanowire results in a transient flow of the electrons in the external load due to the driving force of the piezopotential. We have developed the nanogenerator from fundamental science, to engineering integration and to technological scale-up [3-6]. As today, a gentle straining can output 1-3 V from an integrated nanogenerator [6], using which a self-powered nanosensor has been demonstrated [6]. A commercial LED has been lid up [7, 8]. This is a key step for developing a totally nanowire-based nanosystem [6].
Due to the polarization of ions in a crystal that has non-central symmetry, a piezoelectric potential (piezopotential) is created in the crystal by applying a stress. For materials such as ZnO, GaN, InN in the wurtzite structure family, the effect of piezopotential to the transport behavior of charge carriers is significant due to their multiple functionalities of piezoelectricity, semiconductor and photon excitation. By utilizing the advantages offered by these properties, a few new fields have been created. Electronics fabricated by using inner-crystal piezopotential as a “gate” voltage to tune/control the charge transport behavior is named piezotronics [9], with applications in strain/force/pressure triggered/controlled electronic devices, sensors and logic units [10,11]. Piezo-phototronic effect is a result of three-way coupling among piezoelectricity, photonic excitation and semiconductor transport, which allows tuning and controlling of electro-optical processes by strain induced piezopotential [12]. The objective of this review article is to introduce the fundamentals of piezotronics and piezo-phototronics and to give an updated progress about their applications in energy science and sensors [13,14].
[1] Z.L. Wang “Self-powering nanotech”, Scientific American, 298 (2008) 82-87; Z.L. Wang “Towards self-powered nanosystems: from nanogenerators to nanopiezotronics” (feature article), Advanced Functional Materials, 18 (2008) 3553-3567.
[2] Z.L. Wang and J.H. Song “Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays”, Science, 312 (2006) 242-246.
[3] X.D. Wang, J.H. Song J. Liu, and Z.L. Wang “Direct current nanogenerator driven by ultrasonic wave”, Science, 316 (2007) 102-105.
[4] Y. Qin, X.D. Wang and Z.L. Wang ”Microfiber-Nanowire Hybrid Structure for Energy Scavenging”, Nature, 451 (2008) 809-813.
[5] R.S. Yang, Y. Qin, L.M. Dai and Z.L. Wang “Flexible charge-pump for power generation using laterally packaged piezoelectric-wires”, Nature Nanotechnology, 4 (2009) 34-39.
[6] S. Xu, Y. Qin, C. Xu, Y.G. Wei, R.S. Yang, Z.L. Wang “Self-powered Nanowire Devices”, Nature Nanotechnology, 5 (2010) 366.
[7] G. Zhu, R.S. Yang, S.H. Wang, and Z.L. Wang “Flexible High-Output Nanogenerator Based on Lateral ZnO Nanowire Array”, Nano Letters, 10 (2010) 3151.
[8] S. Xu, B. Hansen and Z.L. Wang “Piezoelectric-nanowire-enabled power source for driving wireless microelectronics” Nature Communications 1 (2010) 93. doi: 10.1038/ncomms1098.
[9] Z.L. Wang “Nano-piezotronics”, Adv. Mater., 19 (2007) 889-992.
[10] J. Zhou, P. Fei, Y.D. Gu, W.J. Mai, Y.F. Gao, R.S. Yang, G. Bao, Z.L. Wang “Piezoelectric-potential-controlled polarity-reversible Schottky diodes and switches of ZnO wires”, Nano Letters, 8 (2008) 3973-3977.
[11] W.Z. Wu, Y.G. Wei and Zhong Lin Wang “Strain-gated piezotronic logic nanodevices “, Adv. Materials, DOI: adma.201001925.
[12] Y.F. Hu, Y.L. Chang, P. Fei, R.L. Snyder and Z.L. Wang “Designing the electric transport characteristics of ZnO micro/nanowire devices by coupling piezoelectric and photoexcitation effects”, ACS Nano, 4 (2010) 1234–1240.
[13] Y.F Hu, Y. Zhang, Y.L. Chang, R.L. Snyder and Z.L. Wang “Optimizing the Power Output of a ZnO Photocell by Piezopotential”, ACS Nano. 4 (2010) 4220-4224.; Corrections: 4 (2010), DOI: 10.1021/nn101631v.
[14] Q. Yang, X. Guo, W.H. Wang, Y. Zhang, S. Xu, D.H. Lien, Z.L. Wang “Enhancing sensitivity of a single ZnO micro/nanowire photodetector by piezo-phototronic effect”, ACS Nano, online, DOI: 10.1021/nn1022878.
[15] Research supported by DARPA, DOE, NSF, Airforce, NIH, Samsung.
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Short Biography
Dr. Zhong Lin (ZL) Wang is the Hightower Chair in Materials Science and Engineering, Regents' Professor, COE Distinguished Professor and Director, Center for Nanostructure Characterization, at Georgia Tech. Dr. Wang is a foreign member of the Chinese Academy of Sciences, member of European Academy of Sciences, fellow of American Physical Society, fellow of AAAS, fellow of Microscopy Society of America and fellow of Materials Research Society. He has received the 2001 S.T. Li prize for Outstanding Contribution in Nanoscience and Nanotechnology, the 1999 Burton Medal from Microscopy Society of America, and the 2009 Purdy award from American ceramic society. Dr. Wang has made original and profound contributions to the synthesis, discovery, characterization and understanding of fundamental physical properties of oxide nanobelts and nanowires, as well as applications of nanowires in energy sciences, electronics, optoelectronics and biological science. He invented and pioneered the in-situ technique for measuring the mechanical and electrical properties of a single nanotube/nanowire inside a transmission electron microscope (TEM). His breakthroughs in developing nanogenerators establish the principle and technological road map for harvesting mechanical energy from environment and biological systems for powering a personal electronics. He initiated, coined and pioneered the field of piezotronics and piezo-phototronics by introducing piezoelectric potential gated charge transport process in fabricating new electronic and optoelectronic devices, which have potential applications in MEMS/NEMS, nanorobotics, human-electronics interface, sensors, medical diagnosis and photovoltaic. Dr. Wang is the world’s top 5 most cited authors in nanotechnology and materials science. He has published four scientific reference and textbooks and over 640 peer reviewed journal articles, 45 book chapters, edited and co-edited 14 volumes of books on nanotechnology, and held 28 patents. His entire publications have been cited for over 37,000 times. The H-index of his citations is 92.
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