Ultrasonic waves to power future nanomachines
05 April 2007
A team of materials scientists has developed an innovative nano-scale power supply which is fuelled by ultrasonic waves. The scientists predict that their nanogenerator could power the next generation of nanomachines - opening up hundreds of applications in the medical and technology industries.1 The generator relies on piezoelectric zinc oxide nanowires that are both durable and flexible. The team, based at the Georgia Institute of Technology, Atlanta, US, had already proved that an array of these nanowires generated small electrical charges when bent or deformed.2 Now, they have managed to harness that electricity into a useful power source.
Close-up image shows a prototype direct-current nanogenerator fabricated by Georgia Tech researchers using an array of zinc oxide nanowires
© Georgia Tech Photo: Gary Meek
So far, the nanogenerator has run continuously for more than an hour. Driven by ultrasonic waves or vibration, nanogenerators like this have the potential for self-sustaining power by harvesting energy from the environment, the scientists suggest. In the same way that a self-winding watch can extract electrical energy from movement, nanogenerators could potentially run forever on normal levels of environmental vibrations.
Zhong Lin Wang, who leads the research team, told Chemistry World, 'The concept and prototype technology established by the DC nanogenerator has already set a platform for developing self-powering nanosystems. There is potential for medical application, such as implantable in-vivo biosensing of blood pressure, blood sugar and even cancer. The technical applications include wireless and remote sensing of gases or chemicals, nanorobotics, microelectromechanical systems and sonic wave detection.'
Schematic (top) showing the direct current nanogenerator. The lower plot is the output from a nanogenerator when the ultrasonic wave was on and off
© Courtesy of Zhong Lin Wang, Georgia Tech
The team plans to continue enhancing their nanogenerators by optimising the growth of the zinc oxide nanowires, to ensure they have a uniform size and distribution over the surface of the array. Their goal is to increase the output voltage to more than 0.5 Volts so that the nanogenerator can be used in practical applications. With continued research, Wang believes that in just three years we could be seeing nanomachines powered by such generators in real-world devices.
1. X Wang, J Song, J Liu & Z L Wang. Science, 2007, 316, 102
2. Z L Wang & J Song. Science 2006, 312, 242
Also of interest
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