Dec 16, 2009
Heat flux powers carbon nanotube actuator
Scientists have come up with various carbon nanotube-based nanodevices or nanomachines including nanoswitches, nanobearings, nanogears and gigahertz oscillators that are powered by electrical, chemical, biochemical or mechanical energies. Recently, the thermal gradient (temperature difference) across a nanoassembly has been experimentally and numerically shown to be capable of driving solid nanoparticles or water nanodroplets.
Researchers at Tsinghua University have used molecular dynamics simulations to examine thermal gradient-induced actuation in double-walled carbon nanotubes and believe that heat flux can actuate the relative motion of double-walled carbon nanotubes. The thermal driving force is on the order of pico Newtons for a 1 K nm–1 temperature gradient. The driving force is found to be approximately proportional to the temperature gradient.
Heading in the right direction
The motion was found to be dependent on the chirality pairs of the double-walled carbon nanotubes. Based on different chirality pairs, the relative motion of the double-walled carbon nanotubes is confined within the minimum energy track and can be rotational, translational or helical (combination of rotational and translational) when the system temperature is less than its critical temperature. The behaviour offers a pathway towards directional control, which could be helpful in the design of future nanodevices.
Full details can be found in the journal Nanotechnology.
About the author
The research was performed at Tsinghua University (THU) and supported by the National Science Foundation of China (No. 50606018) and the Tsinghua National Laboratory for Information Science and Technology (TNList) Cross-discipline Foundation. Quan-Wen Hou is a PhD student studying engineering thermophysics at THU. Bing-Yang Cao is an associate professor and Zeng-Yuan Guo is a leadership professor in the Department of Engineering Mechanics at THU, whose recent interests are micro/nanoscale heat transfer and new concepts in thermal science.