Fig. 3: 3D indentation of C. elegans.

a A fluorescence image of a C. elegans nematode trapped in the vicinity of microbubbles using acoustic radiation forces. The region of interest (ROI), where the mechanical characterization was performed, is highlighted in blue. b An image sequence showing different orientations of a C. elegans nematode. The specimen is rotated using acoustic streaming. c A stationary C. elegans worm near the microbubbles. Red dots indicate the individual positions of the micro-indenter probe during mechanical characterization. d Schematic illustrating the composition of internal organs which might lead to different stiffness values measured by micro-indentation and which can be used to extract the right orientation via fluorescence imaging. The angle θ denotes the location of the indentation in a cylindrical coordinate system. e 3D projection of the stiffness values onto the geometry of a C. elegans nematode showing the different positions around the characterized specimen. f The unfolded stiffness map with individual indentation positions. Multiple bands with different stiffness ranges can be observed. All presented measurements were performed on a single nematode to avoid noise caused by biological variation between specimens. For multicellular organisms, the stiffness does not necessarily quantify a single biological material, but may include the mechanical properties of several overlapping layers and, hence, should be treated as apparent stiffness. Green bands indicate the possible influence of muscular tissue. Scale bars: a = 100 µm, b = 50 µm, c = 50 µm. Source Data is available as a source data file for f.