Decoupling Nonlinear Motion of the Self-Propelled Disk Sensitive to the Metal Salts

Despite advances in inanimate motors, challenges remain in creating novel motors to demonstrate tailorable motion and understanding the complex synergistic mechanisms in biological systems. Consequently, there is an urgent demand for a deeper understanding of programmable motions and stimulus responsiveness in self-propelled motors based on interface science. Herein, a self-propelled camphor system sensitive to additive metal ions is presented, and the key role of metal ion type and concentration in determining the kinematic characteristics of the camphor disk is revealed. The results show that high valence metal ions have a stronger self-propulsion effect, which is attributed to the interaction of the charged metal ions with surfactants and camphor molecules. In addition, the dependence of motion behaviors (including motion speed, mode bifurcation, and oscillation characteristics) on the metal species has been demonstrated. Especially, the motion speed, mode change, and motion characteristics of the self-propelled camphor system in this study, which are sensitive to various metal ions, are expected to be applied to metal ion detection in the environmental field.