Long-range self-governing motion of polymer gel on a gradiently charged insulating substrate

Herein, we report a special poly(vinyl alcohol/dimethylsulfoxide (PVA/DMSO) gel electromechanical system with great self-governed capability. The system is operated in air by applying a non-contacted DC electric field. When the applied electric field exceeds a certain critical value, the gel exhibits fast and self-governing locomotion on the gradiently charged glass substrate. In contrast to field-controlled gel systems developed earlier, the crawling direction of the gel is independent of the direction of the applied electric field and can be actively controlled. The maximum crawling velocity can reach 3.22 mm s ^-1, which is much larger than that of the actuators described earlier. Furthermore, some factors that influence the critical driving electric field and the average crawling speed of the gel were studied. The mechanism analysis indicates that, the self-governing linear motion of the gel is due to the spatially and temporally varying electrostatic interaction between the gel and the applied electric field in response to the gradient change of the charge density and the charge polarity on the substrate.