Charles Lieber, a professor of international nanotechnology and a professor at Harvard University, said: "The work described in this paper is extremely exciting because it proposes a solution to a key problem in nanotechnology, that is how to invent nanodevices for many research groups. Providing power problems. Professor Wang used his first zinc oxide nanowires to convert mechanical energy into electrical energy, which showed his great creativity on this issue." Liu Jun, a material scientist at the Pacific Northwest National Laboratory, said: "This It is a major breakthrough in the field of nanotechnology, and its impact will be profound and far-reaching."
Wang Zhonglin, who is in Beijing, said in an interview, "This is the invention that I am most excited about in this field of research for more than 10 years." He believes that this is the most exciting and significant discovery in the international nano-field, and it will certainly cause a huge upsurge in the research of nano-power in the nano-study community.
As a director of the Georgia Institute of Technology and a professor of engineering, Wang Zhonglin is also the director of the Department of Advanced Materials and Nanotechnology at the School of Engineering, Peking University, and the overseas director of the China National Nanoscience Center. This work was done jointly with his doctoral student Song Jinhui.
Because of its unique advantages, such as small size, low power consumption, and responsiveness, nanodevices have always been the most advanced and active areas in nano-academics. If these tiny devices can really work, they must be powered, and only nanodevices that implement their own power supplies can be considered true nanosystems. Because the nanosystem is small and implantable in the body, its power supply system must be miniaturized. However, the current research is only focused on the nanodevice itself, and does not consider the problem of inputting power to these nanodevices.
Power generation requires energy. When people walk and breathe, they generate energy. Can they convert the energy produced by the body into the energy needed for nanodevices? Wang Zhonglin thought of this idea. He said: "If there is a miniature device that can convert the biological energy in the living body into electrical energy, it is the ideal thing to realize the miniaturization of the device and the power supply."
Wang Zhonglin and Song Jinhui used the unique properties of vertical structure of zinc oxide nanowires to develop a nanogenerator that converts mechanical energy into electrical energy under atomic force microscopy. This is the world's smallest power generation device. Wang Zhonglin explained that the piezoelectric effect is a charge polarization effect caused by mechanical deformation in materials. It is an important physical process for achieving electrical coupling and sensing, and zinc oxide nanowires are easily bent. Compression and stretching can be caused separately inside and outside the nanowire; the vertically grown zinc oxide is a wurtzite structure with both semiconductor properties and piezoelectric effects. This unique structure of zinc oxide nanowires causes polarization charges on the inner and outer surfaces of curved nanowires. They use a probe of a conductive atomic force microscope to bend a single zinc oxide nanowire, input mechanical energy, and then use the semiconductor properties of zinc oxide to nanoscale it. The piezoelectric properties of the wires are coupled to temporarily store electrical energy in the nanowires, and then the conductive AFM probe is used to connect the power supply to the outside world, thereby perfectly achieving the nanoscale power generation function. He said: "More importantly, this nano-generator can achieve 17% energy efficiency of 30%, laying a physical foundation for self-generating nanodevices."
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