Structure-Function Dependence on Template-Based Micromotors

Catalytically bubble propelled micromotors are one of the most frequently used self-propelled micromachines in the literature. Typically, the structure-function relationship is not investigated. We present detailed study of how the structural geometry influences the propulsion of these micromachines. We prepared different micromotors with membrane template-assisted electrodeposition by applying varied electroplating time. We obtained a variety of differently sized micromotors with a range of propulsion dynamics. We used varied electroplating time to tailor the length of the micromotor, but also the wall thickness, microtube opening diameter, and even the structural integrity of the micromotor. The study of propulsion dynamics of micromotors in different H₂O₂ concentrations indicated that both geometric parameters and the chemical environment affect the velocity of micromotors. Microtubular motors prepared by short electrodeposition time (e.g., 300 s) require higher fuel concentration to activate and move. The bubble ejection frequency and diameter were measured and demonstrated that micromotors with shorter length produce smaller bubbles and relatively lower velocities. This fundamental study provides experimental insights into the length-related propulsion dynamics of a microtube, and it has profound implications for the design of micromotors.