Dielectric elastomer sensors for the tongue-computer interface

The training of the human tongue for therapeutic purposes requires suitable feedback from pressure sensor arrays. These sensors have to be biocompatible, soft, and thin enough to be comfortable for patients. Within this thesis, we built a prototype using five dielectric elastomer sensors prepared by electrospinning and thin film technology. The individual sensors comprise of a personalized thermoformed polymer substrate, 66 nm-thin gold layers, 500 nm-thin silicone films, a cellulose acetate butyrate network of about 10 µm thin electro-spun fibers, a top electrode, and a lid. Using cellulose acetate butyrate of 30'000 and 70'000 g mol-1 with a concentration of 13 and 22 wt% in acetone at the flow rates of 10, 50 and 200 mL h-1 and 15 to 20 kV operation voltages, nonwoven networks of fibers with diameters between 0.3 and 20 µm were fabricated and characterized by optical and electron microscopies. The pressure increase from 1 to 100 kPa reduced the framework of the electro-spun fibers by a factor of four. By means of the dielectric elastomer sensors, we detected pressures from 1 kPa to more than 10 MPa with a sensitivity of 10 and 0.17 kPa-1, respectively. The selected parameters for the electrospinning hardly affected the sensor performance. The pressure sensors covered the range of the human tongue from 1 to 100 kPa. Combining these sensors with dielectric elastomer actuators in a single device will enable the localization of the sensors within the oral cavity by the patient. The fabricated prototype is an important milestone towards myofunctional therapy-based treatments of sleep apnea and snoring based on the tongue-computer interface.