Liquid–Vapor Phase-Change Soft Composite Actuator Integrated with a Laser-Induced Graphene Heater

Abstract

Actuators are fundamental components for facilitating actuation and operational functions in diverse industrial and medical applications. Most actuators developed over the past few decades have been composed of rigid materials. However, rigid actuators often face spatial and operational limitations, and this issue has led to a growing interest in actuators made from soft materials. This study proposed and developed a liquid–vapor phase-change soft composite actuator integrated with a laser-induced graphene (LIG) heater. The liquid–vapor phase-change soft composite was prepared by mixing ethanol with the polymer elastomer Ecoflex 00-50. The LIG heater was fabricated on a polyimide substrate through laser ablation. Application of voltage to the LIG heater caused its temperature to rise, which induced a phase change of the ethanol within the composite, ultimately resulting in notable expansion of the soft composite. The LIG heater fabricated using a laser of power 2 W exhibited excellent electrothermal characteristics. Furthermore, the soft composite containing 20 vol % ethanol achieved a strain of 0.2 at 100 °C. The flexural deformation of the proposed soft composite actuator integrated with an LIG heater could be controlled by the specific applied voltage. An average bending curvature of 0.037 mm^–1 was achieved at an applied voltage of 24 V.