Figure 4

Torsional and tensile actuation for all-solid-state electrochemical CNT muscles. (a) Torsional rotation per muscle length, in response to different applied square-wave voltages, which were measured by paddle rotation for a two-ply, twist-spun, CNT yarn that was impregnated with PVDF-co-HFP/TEA.BF₄/PC solid gel electrolyte. The direction of yarn twist was opposite to that applied for yarn plyimg. (b) Data showing the largely non-hysteretic reversal of torsional actuation for the torsional muscle used in (a). (c) Tensile actuation strain and applied voltage versus time for a two-ply yarn muscle, using polyvinyl alcohol/H₂SO₄ electrolyte, while lifting a 11 MPa load. (d) Tensile actuation for the tensile muscle of (c) during three repeated charge (1 V square wave) and discharge cycles that were followed by a hold period, where the power supply was disconnected. Inset: actuator stroke during an extended hold period where no potential was applied, showing that tensile actuation has a latched state, where actuator stroke is largely maintained for an hour without the need for input power [3].