Physical Review Letters (Vol.101, No.17):175501
Highlighted by Nature Nanotechnology, 31 Oct 2008
Highlighted by NatureChina, 5 Nov 2008
A movie at YouTube: http://www.youtube.com/watch?v=nFQPkdoLGW0
Finding a way to release energy stored up by nature or to convert energy into a more useful form is of significant importance for human life, especially when we enter the area of nanotechnology where new challenges arise due to the small size of nanomachineries. Although recent advances in fabrication of nanoelectromechanical systems (NEMS) devices have marked milestones in converting electronic energy into mechanical energy (1-4) or conversely (5,6), the energy supply to a NEMS device remains to date a challenge. Design of devices which use their intrinsic energy to function is therefore conceptionally important.
A typical character of an energy supplier is that there exists a potential difference. Recent studies (7-13) have shown that a single walled carbon nanotube (SWCNT) with an appropriate diameter (2-6 nm) has two stable states (i.e., circular and collapsed structures) with different potential energy in most cases. This implies that such a potential difference may be used as an energy source during the transformation of the two states. Namely, a carbon nanotube can simultaneously be a structural element and an energy supplier in a device.
We demonstrate here via molecular dynamics simulations that the van der Waals potential energy stored up in SWCNTs can be released by a surprising physical phenomenon, domino process, allowing a SWCNT to be an energy provider. A nano gun driven by the domino process is proposed as an example. Although carbon nanotubes (CNTs) have found applications as many NEMS devices, they serve as either structural elements or energy consuming elements. Our finding is for the first time to show that a SWCNT can be an energy supplier and is thus a useful complement to the current studies on CNT based NEMS devices. In addition, it has been shown that a molecular domino cascade may be used to perform mechanical calculation on the nanometer length scale. Our finding provides therefore opportunities for designing new concept (domino-driven) NEMS devices of expelling systems or computing systems.
Reference List
1. Fennimore, A. M. et al. Rotational actuators based on carbon nanotubes. Nature 424, 408-410 (2003).
2. Sazonova, V. et al. A tunable carbon nanotube electromechanical oscillator. Nature 431, 284-287 (2004).
3. Jensen, K., Weldon, J., Garcia, H. & Zettl, A. Nanotube Radio. Nano Lett. 7, 3508-3511 (2007).
4. Shim, S. B., Imboden, M. & Mohanty, P. Synchronized Oscillation in Coupled Nanomechanical Oscillators. Science 316, 95-99 (2007).
5. Wang, Z. L. & Song, J. Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays. Science 312, 242-246 (2006).
6. Wang, X., Song, J., Liu, J. & Wang, Z. L. Direct-Current Nanogenerator Driven by Ultrasonic Waves. Science 316, 102-105 (2007).
7. Chopra, N. G. et al. Fully collapsed carbon nanotubes. Nature 377, 135-138 (1995).
8. Benedict, L. X. et al. Microscopic determination of the interlayer binding energy in graphite. Chem. Phys. Lett. 286, 490-496 (1998).
9. Gao, G., Cagin, T. & Goddard, W. A. Energetics, structure, mechanical and vibrational properties of SWNTs. Nanotechnology 9, 184-191 (1998).
10. Yu, M. F., Dyer, M. J. & Ruoff, R. S. Structure and mechanical flexibility of carbon nanotube ribbons: An atomic-force microscopy study. J. Appl. Phys. 89, 4554-4557 (2001).
11. Liu, B., Yu, M. F. & Huang, Y. Role of lattice registry in the full collapse and twist formation of carbon nanotubes. Phys. Rev. B 70, 161402 (2004).
12. Tang, T., Jagota, A., Hui, C. Y. & Glassmaker, N. J. Collapse of single-walled carbon nanotubes. J. Appl. Phys. 97, 074310-074316 (2005).
13. Chang, T., Hou, J. & Guo, X. Reversible mechanical bistability of single-walled carbon nanotubes under axial strain. Appl. Phys. Lett. 88, 211906-3 (2006).