3-D prints the first surface of the biomimetic tongue

Scientists have created soft synthetic surfaces with tongue-like textures for the first time using 3-D printing, opening up new possibilities for testing the oral processing properties of foods, nutritional technologies, medications and therapies for dry mouth.

British scientists led by the University of Leeds in collaboration with the University of Edinburgh have replicated the highly sophisticated surface design of a human tongue and demonstrated that their molded synthetic silicone structure mimics the topology, elasticity and wettability of the surface of the tongue.

These factors are critical to how food or saliva interacts with the tongue, which in turn can affect mouthfeel, swallowing, speech, nutritional intake and quality of life.

A biomimetic language will help developers screen newly developed products and accelerate new development processes without the need for early human testing which is often very expensive and time consuming.

In particular, since the onset of the COVID-19 pandemic, social distancing has posed significant challenges to conducting such sensory testing and consumer testing. A biomimetic language will be immensely useful for increasing development productivity and reducing producers’ dependence on human experimentation in the early stages.

A biomimetic language could also offer a myriad of applications to combat adulteration in food and other orally administered pharmaceuticals, regardless of whether textural attributes govern characteristics and can save huge economic losses.

The complex nature of the biological surface of the tongue has posed challenges in artificial replication, adding major obstacles to the development and screening of effective long-lasting treatments or therapies for dry mouth syndrome: approximately 10% of the general population and 30% of elderly suffer from dry mouth.

The study’s lead author, Dr Efren Andablo-Reyes, conducted this research while he was a postdoctoral fellow at the School of Food Science and Nutrition in Leeds. He said: “Recreating the surface of an average human tongue involves unique architectural challenges. Hundreds of small bud-like structures called papillae give the tongue its characteristic rough texture which, in combination with the soft nature of the fabric, creates a landscape complicated by a mechanical perspective.

“We focused our attention on the anterior dorsal section of the tongue where some of these papillae contain taste receptors, while many of them lack these receptors. Both types of papillae play a vital role in providing the right mechanical friction to aid processing. of food in the mouth with an adequate amount of saliva, providing a pleasant perception of the palate and proper lubrication for swallowing.

“We aimed to replicate these mechanically relevant features of the human tongue in a surface that is easy to use in the laboratory to replicate oral processing conditions.”

The study that brought together unique expertise in food colloid science, soft matter physics, dentistry, mechanical engineering and computer science was published today in the journal ACS applied materials and interfaces.

The team took silicone impressions of the tongue surface from fifteen adults. The impressions were optically scanned in 3-D to map the papillae size, density and mean roughness of the tongues. It turned out that the texture of a human language resembles a random layout.

The team used computer simulations and mathematical models to create an artificial 3-D printed surface that functioned as a mold containing wells with the shape and size of different papillae distributed randomly across the surface with the right density. This was replicated against elastomers of optimized softness and wettability.

University of Edinburgh co-author Rik Sarkar of the School of Informatics said: ‘Randomness in the distribution of the papillae appears to play an important sensory role for language.

“We have defined a new concept called collision probability to measure mechanosensory that will have a big impact in this area. In the future, we will use a combination of machine learning and computational topology to create language models of different healthy and sick individuals to address various problems. oral. conditions. “

The artificial surface was then printed in 3-D using digital light processing technology based at the School of Mechanical Engineering in Leeds.

The team conducted a series of experiments using several complex fluids to ensure that the wettability of the printed surface, i.e. how a liquid maintains contact and spreads over a surface, and the lubrication performance was the same as the tongue impressions. Human.

Co-author Dr. Michael Bryant of the Leeds School of Mechanical Engineering said: “The application of bio-tribological principles, the study of friction and lubrication, in creating this tongue-like surface is a significant step forward in this field.

“The ability to produce accurate replicas of tongue surfaces with similar structure and mechanical properties will help simplify research and development for oral hygiene, food and therapeutic technologies.”

Lead researcher Anwesha Sarkar, Professor of Colloids and Surfaces at Leeds, said: ‘Accurately mapping and replicating the surface of tongues and combining it with a material that comes close to the elasticity of the human tongue was no small task. ‘experience of multiple STEM disciplines, we “have demonstrated the unprecedented ability of a 3-D printed silicone surface to mimic the mechanical performance of the human tongue.

“We believe that fabricating a synthetic surface with relevant properties that mimics the complex architectural features and, more importantly, the lubricating performance of the human tongue is critical to gaining a quantitative understanding of how fluids interact within the oral cavity.

This biomimetic surface of the tongue could also serve as a unique mechanical tool to help detect counterfeiting in high-value food and beverages based on structural attributes, which is a global concern and can help ensure food safety.

“Ultimately, our hope is that the surface we have designed will be important in understanding how the biomechanics of language underlies the fundamentals of human nutrition and language.