Design of an Artificial Tongue Driven by Shape Memory Alloy Fibers

Dysphasia is one of the complications which may cause functional disability after the surgical treatment of oral cancer. The loss of the function derived by tongue and other oral tissues impairs the retention and delivery of liquids and food masses as well as the swallowing motion into pharynx. As accumulation of liquids or food masses in the larynx can lead to pneumonia, therefore swallowing support to improve each coordination of the tongue, the epiglottis and the esophagus in the process of swallowing is highly desirable. In this study, we designed a new artificial tongue which was capable of contracting to deliver the bolus masses in the swallowing propulsion phase in the oral cavity. We designed a two-layered artificial tongue simulating the anatomical identical muscle structures with the longitudinal muscle, and the transverse muscle-genioglossus layer. A silicone rubber material was used for the surface layer, and the covalent shape memory alloy fibers (diameter: 150µm) were implemented in the secondary structure beneath of the silicone rubber material of the artificial tongue. Its contraction was driven by with shape memory alloy fibers shortage inside of the artificial tongue unit. The actuation was accurately controlled by the originally designed electrical current input with pulse width modulation. Firstly, we examined a prototype structure of the artificial tongue as well as the changes in unit thickness as it constricted by electric power supply switching. Secondly, we performed a feasibility study of the prototype into the head-neck medical training model with larynx-tracheal structure with esophagus. The results were as follows: a) the artificial tongue model showed a large contraction with a motion to increase upward pressure, b) the tongue unit expressed the capability of reducing shallow space between dorsal tongue surface and palate in the oral cavity model. Therefore, the first artificial tongue design with active contractile motion will be useful orally installable device for improving delivery function of bolus masses through swallowing procedure in dysphasia.Clinical Relevance- The active artificial tongue system designed for the first time exhibited an effective contractile motion to support bolus food masses propulsion in swallowing process in the oral cavity in the patients with dysphasia.