Wireless Dual Stimuli Actuation of Dye Sensitized Conducting Polymer Hybrids

Actuators controlled by external stimuli have received a lot of attention in recent years. Herein a polymer based dual stimuli actuator is reported, triggered by light and an electric field. This allows better control of actuation, enlarging the field of potential applications, like, for example, in the frame of soft robotics. The actuator is composed of polypyrrole and TiO₂ modified with methylene blue. In an aqueous solution, the resulting freestanding hybrid film shows reversible actuation due to the synergy of light and an applied electric field. Illumination with light produces electron-hole pairs in the TiO₂ layer, which are shuttled to the opposite ends of the actuator by the potential gradient present in the solution. This results in electrochemical oxidation and reduction reactions at the two extremities and consequently in site selective swelling of the polymer, which finally leads to a controlled motion of the actuator, following the principles of logic gate operations. Such synergistically induced switching allows developing original actuation schemes for performing complex mechanical tasks triggered by more than one stimulus.