3D silicone surface mimics the surface features of the human tongue

The tongue helps people taste food, but structures on its surface also help them sense textures -- something that's also very important when savoring a meal.

Now, researchers reporting in ACS Applied Materials & Interfaces have made a 3D silicone surface that, for the first time, closely mimics the surface features of the human tongue. The material could help food scientists study mechanical interactions of foods, liquids and medicines with the organ.

In humans, the tongue is essential for moving food around in the mouth, sensing taste and texture, and speech. The surface of the tongue is covered in thousands of tiny bumps, or papillae, that contain the taste buds and provide friction and lubrication.

Studying how foods and liquids mechanically interact with the tongue could help food scientists, drug developers and manufacturers of toothpastes or mouthwashes make more desirable products.

Currently, scientists rely mainly on human tasters to assess texture, or mouth feel, but this is time-consuming, expensive and subjective.

There are electronic tongues, or e-tongues, available, but most analyze taste, and the few developed to study texture aren't very accurate. Anwesha Sarkar and colleagues wanted to develop a soft 3D surface that replicates the topography and wettability of a real human tongue.

The team began by making silicone masks of the tongue surfaces of 15 healthy adults. Using 3D optical scanning and computational surface reconstructions, they created digital models and measured the average density, diameter and height of the two major two types of papillae.

Next, they designed a master mold with the appropriate spatial distribution of these papillae and 3D printed it. Then, they used the mold to make soft, tongue-like surfaces out of silicone, with a surfactant added to improve wettability.

Testing showed that the 3D biomimetic surface demonstrated similar frictional properties to an actual human tongue, and simulations showed similar mechanical sensing properties. The tongue-like surface could help accelerate the development of nutritional, biomedical and clinical products, as well as find applications in soft robotics, the researchers say.