REF 11: The material-based actuations provide opportunities for utilizing the material itself to replace mechanical or electro-mechanical components. The material-based actuators operate based on molecular changes in the material structures when they are stimulated by external signals such as photons of lights, temperature changes, chemical substances, magnetic field forces, and electricity flows. Several smart materials, such as shape memory alloys, shape memory polymers, electroactive polymers, and phase changing materials, could be used as actuators and sensors in the structure of responsive facades.