Figure 3

Flow speed measurement. The thin metal layer inside the body of each micro-tool is heated using a laser beam (1070 nm), which, in turn, creates a microbubble and generates strong thermal convection currents that gradually draw the cargo toward the spout of the micro-tool. We use a feature tracking algorithm to monitor the movement of the beads. The zero position is set at the spout of the micro-tool. The clear gap observed in the velocity plot is due to the limitation of the tracking algorithm to identify the bead when it crosses the dark outline of the micro-tool. The blue and red plots represent the velocity of the bead while it is outside and inside of the micro-tool, respectively. An image of a micro-tool is added to give a scale-indication of the horizontal axis. See Supplementary Material.