Fig. 4.

(a) Schematic of the DOL. When applying an electric field to the electrodes, the liquid interface, L-L, is modulated. (b) Focal length shifting according to the EHD flow. (c) A wide-field optical image of a 7-μm carbon fiber (left) and its PA MAP images before (middle) and after (right) adjusting the focal length. DOL, dielectro-optofluidic lens; EHD, Electrohydrodynamics; PA, photoacoustic; MAP, maximum amplitude projection; L₁ and L₂, immiscible liquids; y and y’, the height of L-L interface; R and R’, curvature; and F and F’, focal length. Reproduced from Ref. [63] with permission from The Royal Society of Chemistry.