Without tweezers, how to pick up a millimeter-sized particle from a ground immersed in water? In this video, we provide a noninvasive solution--to use vapor bubbles. When we focus a laser pulse on the spot in the water nearby the immersed particle, a short-lived cavitation bubble is generated and it lifts the particle to several centimeters high. With high-speed photography, we observe that the particle detaches from the substrate during the bubble’s explosive growth. This indicates that the particle is subjected to a strong lift force provided by the bubble. The reason for the lift force is the unique pressure distribution on the particle, which is induced by cavitation bubble dynamics and described by the Rayleigh equation. The maximum lift force is calculated as more than 100 times the particle’s weight, showing that bubbles with “soft” interfaces have huge power. By changing the size and the position of the bubble, the particle’s trajectory is controllable. Moreover, this principle can be applied to lifting particles with curved bottoms.
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