Figure 4.

Scheme of ‘bulk’ and ‘drop’ geometries used to perform microrheological measurements. The bulk geometry (1 cm × 1 cm × 100 µm) is the usual geometry for performing microrheological measurements. The ‘drop’ geometry was used with the secretion in the present work, owing to the extremely small amount of fluid available. The drop size was 100 µm in diameter and 30 µm in height. The ‘drop’ geometry was shown to provide the same viscosity results as the usual bulk geometry, which shows that it is reliable.