Carbon Nanotube Actuators

TLDR

Macroscopic actuators consist of billions of nanoscale actuators, analogous to natural muscle. Actuation arises from quantum‑chemical expansion via electrochemical double‑layer charging, avoiding ion intercalation that limits polymer actuators. Carbon‑nanotube sheets generate stresses exceeding natural muscle and strains surpassing high‑modulus ferroelectrics at only a few volts, with predictions of even higher work densities per cycle.

Abstract

Electromechanical actuators based on sheets of single-walled carbon nanotubes were shown to generate higher stresses than natural muscle and higher strains than high-modulus ferroelectrics. Like natural muscles, the macroscopic actuators are assemblies of billions of individual nanoscale actuators. The actuation mechanism (quantum chemical-based expansion due to electrochemical double-layer charging) does not require ion intercalation, which limits the life and rate of faradaic conducting polymer actuators. Unlike conventional ferroelectric actuators, low operating voltages of a few volts generate large actuator strains. Predictions based on measurements suggest that actuators using optimized nanotube sheets may eventually provide substantially higher work densities per cycle than any previously known technology.