Supplementary Figure 2: Ferrofluid droplet actuation in a hydrocarbon oil.
From: In vivo quantification of spatially varying mechanical properties in develo** tissues
Temporal evolution of the strain (solid black circles) during the actuation cycles shown in Supplementary Video 1. At equilibrium, the magnetic stress (orange dashed line with fill) is balanced by the capillary stress, leading to the saturation of the strain at each actuation cycle. The characteristic time scale of the dynamics depends on the viscosity of the outer medium (in this case a hydrocarbon oil) because the ferrofluid droplet viscosity is negligible (see Methods). Therefore, the dynamics of ferrofluid droplet actuation permits the measurement of the local hydrocarbon oil viscosity around the droplet.