AFM micropipette cleaning procedure when using the organic dye rhodamine 6G.

(a-c) Bright-field images of four sequentially spotted droplets (pos. 1, 3 and 4: glycerol-water; pos. 2: 50 μM rhodamine 6G); micropipette silhouette can be seen in the background; scale bar = 50 μm. (d-f) Corresponding fluorescence images of the identical regions shown in (a-c) with associated intensity profile plots along the red lines; λex = 485 nm ± 15 nm, λem = 535 nm ± 25 nm; time periods between the delivery of the individual droplets: 1 to 2 in 12 min, 1 to 3 in 39 min, 1 to 4 in 70 min.