Hydrogen bubble propelled tubular micromotor engineered via self-rolling of nanomembrane

Micromotors demonstrate significant potential in environmental sensing, targeted biomedical therapeutics, and microscale engineering applications due to their miniaturized architecture and ability to harness environmental energy for autonomous propulsion. Nevertheless, current magnesium (Mg)-based micromotors predominantly utilize Mg microspheres as their structural foundation, restricting geometric diversity and limiting performance improvements. This paper presents a self-propelled Mg-based micromotor fabricated via the self-rolling of titanium (Ti)/magnesium (Mg) bilayer nanomembranes. Through synergistic integration of nanomembrane patterning, bilayer stress engineering, and directional sacrificial layer release, we achieved programmable assembly of three-dimensional (3D) single-tube and V-shaped double-tube architectures. The V-shaped double-tube micromotor features a hollow, asymmetric architecture with expanded Mg-acetic acid (CH₃COOH) interfacial contact area. This configuration enables directional ejection of the generated hydrogen bubbles, thereby enhancing propulsion force and increasing speed. The double-tube micromotor achieved a propulsion speed of approximately 203 μm/s in a solution of 1.2 % CH₃COOH, significantly outperforming the 52 μm/s speed of single-tube and surpassing the speed of Janus Mg microspheres in strong acid. The Mg-based micromotor proposed in this study features structural versatility and preferable motion performance. Combined with the known biocompatibility of Ti/Mg and the therapeutic potential of hydrogen, this work may hold potential for future applications in targeted drug delivery and hydrogen-mediated synergistic therapy.