  An experimental biomimetic tongue-palate system has been developed to probe
human in-mouth texture perception. Model tongues are made from soft elastomers
patterned with fibrillar structures analogue to human filiform papillae. The
palate is represented by a rigid flat plate parallel to the plane of the
tongue. To probe the behavior under physiological flow conditions, deflections
of model papillae are measured using a novel fluorescent imaging technique
enabling sub-micrometer resolution of the displacements. Using optically
transparent newtonian liquids under steady shear flow, we show that
deformations of the papillae allow determining their viscosity from 1 Pa.s down
to the viscosity of water of 1 mPa.s, in full quantitative agreement with a
recently proposed model [Lauga et al., Frontiers in Physics, 2016, 4, 35]. The
technique is further validated for a shear-thinning and optically opaque dairy
system.
