Low-voltage bending actuators from carbide-derived carbon improved with gold foil

Abstract

We report carbide-derived carbon (CDC) based polymeric actuators for the low-voltage applications. The CDC-based actuators have been designed and fabricated in combination with gold foil. The gold-foil-modified actuators exhibited high frequency response and required remarkably low operating voltage (as low as ±0.25 V). Hot-pressed additional gold layer (thickness 100 nm) ensures better conductivity of polymer supported CDC electrodes, while maintaining the elasticity of actuator. Energy consumption of gold-foil-modified (CDC/gold) actuators increased only at higher frequency values (f > 1 Hz), which is in good correlation with enhanced conductivity and improved charge delivery capabilities. Electrochemical measurements of both actuators performed at small operating frequency values (f < 0.01 Hz) confirmed that there was no difference in consumed charge between conventional CDC and CDC/gold actuators. Due to enhanced conductivity of CDC/gold actuators the accumulated charge increased at higher operating frequency values, while initiating larger dimensional changes. For that reason, the CDC/gold actuators exhibited same deflection rate at much lower potential applied. Electrochemical impedance measurements confirmed that relaxation time constant of gold-foil-modified actuator decreased more than one order of magnitude, thus allowing faster charge/discharge cycles. Gold-foil-modified actuators obtained the strain level of 2.2 % when rectangular voltage ±2 V was applied with frequency 0.5 Hz. The compact design and similar working principle of multi-layered actuator also provides opportunity to use actuator concurrently as energy storage device. From practical standpoint, this device concept can be easily extended to actuator-capacitor hybrid designs for generation of energy efficient actuation.