Figure 31.

Optically actuated thermocapillary movement of an air bubble in silicone oil. A 114-µm-diameter (1.0 nL) bubble is trapped in the thermal trap created by a laser focused on the absorbing substrate (a). The oil/air meniscus can be seen at the top left. The bubble follows the position of the laser spot, as it is scanned in the positive y direction (b) and then in the positive × direction (c). The bubble is then moved in the negative y and negative x directions (d). A dashed circle indicates the initial bubble position, and a dashed line indicates the approximate trajectory of the bubble. Reprinted with permission from [70]. Copyright 2007, American Institute of Physics.