|A zinc oxide nanowire can be attached to a rat's heart, producing electric current as the heart bends with every beat. (Photo by Guang Zhu, Georgia Tech)|
Last year, Medtech Pulse reported that Zhong Lin Wang, a professor of materials science and engineering at Georgia Tech (Atlanta), had developed minuscule piezoelectric generators that enable nanosensors to power themselves. This technology could eventually lead to medical implants and sensors powered by heartbeats, breathing, or other body movements. Now, Wang's research team has gone a step further, demonstrating that the nanogenerator works inside live animals.
As reported in MIT's Technology Review, the researchers deposited a zinc oxide nanowire on a flexible polymer substrate and encapsulated the device in a polymer casing to shield it from body fluids. The nanowire was then attached to a rat's diaphragm. Stretched by the animal's breathing, the wire generated 4 pA of current at 2 mV. When it was attached to a rat's heart, the device provided 30 pA of current at 3 mV. These findings are reported in the journal Advanced Materials.
Zinc oxide nanogenerators would be suitable for powering nanoscale sensors that monitor such body functions as blood pressure or glucose levels. However, the femtowatt-scale power generated by Wang's current-generation devices is far too low to be practical. To overcome this limitation, the research team has built a device that integrates hundreds of nanowires in an array. While it has not been tested on live animals, this device provides an output current of about 100 nA at 1.2 V, producing 0.12 µW of power, as reported in the journal Nature Nanotechnology. The next step, Wang notes, is to connect this higher-output nanogenerator to a nanosensor inside an animal.
For more information on this piezoelectric nanowire technology, view Wang's presentation at the MPMN Webcast "Emerging Technologies Showcase."