Uncover the physical mechanics behind the micro-swimmer's movement
Chemical trace visualization. (A) Schematic of the experimental setup for fluorescent microscopy of charged micelle traces. CB15 droplet diameter a drop =50 was injected into a quasi-2D microfluidic cell (height = 50 m) and observed using a bright-field or fluorescent microscope. (B) A fluorescence micrograph of a chemical trace droplet, with the surfactant concentration increased to 15% by weight to increase the visibility of the trace (increased solubility level). (C) Enlarged view of B. (D) Schematic of the drip propulsion mechanism. Black arrows indicate the direction of movement. (E) The flow field generated by the Marangoni flow at the droplet interface visualized by the streak lines of a 0.5 m fluorescent tracer colloid (droplet reference frame). (F) Time evolution of fluorescent intensity (in arbitrary units [a.u.]) profile along AA (Inset) superimposed with Gaussian fit (5 wt% surfactant concentration). (G) Peak intensity vs. time. The ze