Figure 4: Experimental demonstration of the edge-tracing effect. (a) A time sequence of fluorescence micrographs showing actin filaments moving on a disk-shaped motility supporting TMCS surface surrounded by hydrophilic and negatively charged PMMA (see inset with schematic illustration of topography between full white lines in rightmost micrograph in first row). The lack of actin binding on PMMA indicated by red and yellow filaments floating in solution. Note that several of the HMM-propelled actin filaments on the disk-shaped TMCS-derivatized region move along the border of the motility supporting area. (b) Fluorescence micrograph integrated over 60 s to show sliding trajectories of 8 motile filaments (4 stationary filaments) sliding at velocity of about 3 μm/s. (c) Intensity profile indicating the density of actin filaments along the gray area in (b). (d) Time-integrated and color-enhanced fluorescence micrograph illustrating path of a filament (length 3.5 μm) entering a channel (yellow-green area) from an open zone at the arrow. The image is not to scale but magnified 2 𝑥 vertically in order to more clearly illustrate the lateral position of the filament inside the channel. Green: approximate bottom channel borders (width 700 nm; LOR walls). Yellow: approximate top channel position (width 600 nm; with PMMA walls) for the type of channels illustrated in Figure 1. Figure 4(d) reproduced from [27] (DOI: 10.1088/0957-4484/16/6/014) with permission from Institute of Physics.