Research / 2020 / Article / Fig 1

Research Article

Mg-Based Micromotors with Motion Responsive to Dual Stimuli

Figure 1

Schematic illustration of the Mg-based micromotor showing motion responsiveness to dual stimuli of temperature and H2O2 concentration. (I) The driving mechanism of the Mg-based micromotor is transformed from self-consuming Mg-H2O reaction to Pt-catalyzed H2O2 decomposition once H2O2 appears in the solution. (II) Temperature-induced volume phase transformation of PNIPAM induces the transformation of motion behaviors. When temperature is lower than LCST, the covered PNIPAM hydrogel layer swells to increase the amount of permeated H2O2 and thus the catalytically generated oxygen on the side of the PNIPAM hydrogel layer, resulting in a self-limitation motion of the Mg-based micromotor like hovering due to bubble O2 recoils from bilateral sides. (III) Concentration gradient of H2O2 induces the transformation of motion behaviors. Increasing H2O2 concentration raises the H2O2 concentration gradient between the two sides of the hydrogel layer, which facilitates H2O2 to cross the PNIPAM hydrogel layer and react with the middle Pt layer to form O2 bubbles. Consequently, a self-limitation behavior of the Mg-based micromotor occurs due to bilateral O2 bubble generation.