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Science & Technology

March 23, 2009
Volume 87, Number 12
p. 36

Science & Technology Concentrates

Muscular Nanotubes

Aerogels built from carbon nanotubes turn electrical into mechanical energy

Jyllian N. Kemsley

Video

Flexing Muscles

A CNT aerogel sheet expands when a positive voltage is applied and returns to its normal shape when the voltage is removed.

Launch Video
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Aerogels made from carbon nanotubes (CNTs) can serve as electrically powered artificial muscles, reports a group led by Ray H. Baughman of the University of Texas, Dallas (Science 2009, 323, 1575). Such actuators, which turn electrical energy into mechanical energy, have possible applications in robotics, prosthetic devices, and microscopic pumps. The nanotube aerogel sheets are drawn out of forests of multiwalled CNTs such that the nanotubes line up along the length of the sheet. When a positive voltage is applied to the sheet, the sheet becomes about 220% wider and thicker because of electrostatic repulsive forces. The sheets flex about three orders of magnitude faster and generate more than 30 times the force compared to the same cross-sectional area of natural human muscles. They also work over a wide range of temperatures, from 80 to 1500 K, so they may be most useful in extreme environments such as aerospace applications, Baughman says. Additionally, because the density of the sheets changes as they widen and thicken, they may also have applications as tunable electrodes for applications such as solar cells and organic light-emitting displays.

CNT aerogel sheets, which are 50 mm long and 2 mm wide, become wider when exposed to a positive voltage. © 2009 Science
CNT aerogel sheets, which are 50 mm long and 2 mm wide, become wider when exposed to a positive voltage.

» Science & Technology Concentrates

» Indolactam Directs Stem Cell Differentiation

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» Stable AFM In Air

Setup makes method suitable for probing biological systems and nanomanufacturing.

» Muscular Nanotubes

Aerogels built from carbon nanotubes turn electrical into mechanical energy.

» Asymmetric Coupling In Water

Stereoselective version of the popular Suzuki-Miyaura reaction has no need for organic solvents.

» Dust May Hurt Phytoplankton

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» Pyrolysis Products Intrigue

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» Leaching From Plastic Bottles

Mineral water packaged in plastic bottles has higher levels of estrogen mimics than that housed in glass bottles.

» New Linker Combo Gives Novel MOF

Metal-organic framework compound suggests surface area alone may not be predictive of these materials' hydrogen storage-ability.

Flexing Muscles

A CNT aerogel sheet expands when a positive voltage is applied and returns to its normal shape when the voltage is removed.

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