Electro-thermo-elastomers for artificial muscles

This paper presents the concept, design and characterization of new type of thermal actuator, which utilizes the entropic properties of natural rubber elastomer. For a stretched elastomer the thermal expansion is negative above its glass transition temperature. The actuator presented in this study comprised an elastomer film and flexible resistive heater realized by photo-etching a Nickel–Silver photosensitized wafer. The results demonstrated that the thermal actuator was able to generate a strain of 5% and a stress of 1 MPa for an input electric energy of 25 J, i.e. a strain comparable to human muscles mechanical properties.