Giant-Stroke, Superelastic Carbon Nanotube Aerogel Muscles

TLDR

Improved electrically powered artificial muscles are needed for generating force, moving objects, and accomplishing work, and the solid‑state–fabricated sheets are enthalpic rubbers with gas‑like density and higher one‑directional specific strength than steel plate. Actuation decreases nanotube aerogel density, can be permanently frozen for applications such as transparent electrodes, and the resulting giant Poisson’s ratios explain the opposite sign of width and length actuation, yielding negative linear compressibility and stretch densification. Carbon nanotube aerogel sheets, the sole component of new artificial muscles, deliver giant elongations of 220 % and elongation rates of 3.7 × 10⁴ % s⁻¹ across 80–1900 K, with Poisson’s ratios reaching 15—30 times higher than conventional rubbers—enabling negative linear compressibility and stretch densification.

Abstract

Improved electrically powered artificial muscles are needed for generating force, moving objects, and accomplishing work. Carbon nanotube aerogel sheets are the sole component of new artificial muscles that provide giant elongations and elongation rates of 220% and (3.7 × 10 4 )% per second, respectively, at operating temperatures from 80 to 1900 kelvin. These solid-state–fabricated sheets are enthalpic rubbers having gaslike density and specific strength in one direction higher than those of steel plate. Actuation decreases nanotube aerogel density and can be permanently frozen for such device applications as transparent electrodes. Poisson's ratios reach 15, a factor of 30 higher than for conventional rubbers. These giant Poisson's ratios explain the observed opposite sign of width and length actuation and result in rare properties: negative linear compressibility and stretch densification.