Fig. 5: Design of tongue-inspired biomimetic surface.
a Diagram of the mouth arch with a chocolate prototype, where the yellow plane approximately indicates the separation between anterior and posterior tongue regions with their distinct afferent nerves, the chorda tympani nerve (cranial nerve VII) and the glossopharyngeal nerve (cranial nerve IX). On the right, the boundary region between the tongue and chocolate/dots is shown at a greater magnification. The elastic tongue completely coats the semi-spherical surfaces of the dots, and the sample is sheared against the tongue/palate during consumption. b Diagram of the in-vitro simulation of drop melting, using a tongue-emulating elastomeric surface. The elastomer contained two types of human papillae (i.e., filiform and fungiform) that were produced by additive manufacturing. Sample consumption was emulated by oscillating the chocolate sample at a velocity vT of 10 mm/s, at a normal force FN of 1 N, and over an amplitude of sample-to-tongue A/2 of 5 mm. Human tongue movement and in-mouth normal force have been estimated to be in the range applied in our experimental setup44,45. c Dot melting is illustrated in four exemplary photos: At the beginning, the dot shape was completely intact and was sheared against the papillae while the tongue was slowly deforming under the normal force applied. In the later stages, the dot matrix was incrementally distributed close to the initial dot-to-tongue position, at maximum distances restricted by the amplitude between the sample and the tongue surface. A time grid of more selected images can be viewed in Supplementary Fig. 3.
