High-power actuators made of two-phase magnetic gels

The magnetic field-induced elongation of magnetic gels consisting of poly(vinyl alcohol) (PVA) and magnetic particles was analyzed. The elongation increased as the concentration of magnetic particles increased, and inversely it decreased as the cross-linking density increased. We propose a simple theoretical expression of the elongation taking into consideration the elastic modulus of magnetic gels. We have fabricated a high-power actuator made of magnetic gels consisting of a thin magnetic-gel phase and a thick PVA-gel phase. A maximum strain of 33% was achieved while sustaining a constant stress of 1.3 kPa using a magnetic field of 900 mT. The magnetic gel showed a maximum stress of 6.8 kPa and a strain of approximately 10%. Magnetic gels consisting of two gel phases have great potential for application in practical actuators that can be driven by a magnetic field.