A phase change microactuator based on paraffin wax/expanded graphite/nickel particle composite with induction heating

•A novel microactuator using a phase change material (PCM) composite and induction heating was introduced.•The ratio of paraffin wax in the electrical conductive PCM composite is higher than 95% and the PCM composite has a larger expansion.•Eddy current and Joule heating are generated in the PCM composite. The microactuator has no wire or electrodes to connect with the conductive PCM composite.•The new microactuator has some advantages such as ease of fabrication, small-sized, low cost, and ease of integration into Micro-Electro-Mechanical Systems (MEMS). This paper presents a new microactuator using a phase change material (PCM) composite with induction heating. The PCM composite is consisting of paraffin wax, expanded graphite and nickel particle, which was used as an electrical conductive phase change material with improved magnetic permeability. Expanded graphite was used as an electrical conductive porous matrix absorbed with paraffin wax and nickel particle. This work relies on induction heating generated in the PCM composite with eddy current, rather than using external resistive heater. Experiments show that about 140 μm actuation height was realized in 5 s with the input power of 1.42 W at excitation frequency of 1 kHz. Since an induction heating method is adopted with electrical conductive PCM composite, which means the new microactuator has no wire or electrodes to connect with the conductive PCM composite. The new PCM-composite-based microactuator has some advantages, such as ease of fabrication, small-sized, low cost, and eases of integration into Micro-Electro-Mechanical Systems (MEMS).