A Tongue-Based Computer Control for Disabled People

For the ICCHP conference held in July 2006, Lotte N. S. Andreasen Struijk of the Center for Sensory Motor Interaction, Aalborg University, delivered a paper on a tongue-based computer interface system developed for the disabled to access computers and new technologies.

Without suitable input devices, computers would be inaccessible to people who are unable to use their limbs. A lot of research is done in designing assistive technology products that can use input devices other than arms and legs to work on computers. Tongue movements, head movements, jaw movements and eye selection methods can be used as other input sources. Of these, it is generally observed that tongue control methods are favorable. To list some of the advantages, the tongue is considered a portal to the brain and it can be used to provide a good tactile environment for people with severe disabilities, including the blind. Tongue-based technology tools are also easy to manage. Additionally, such systems are almost invisible to other people.

A tongue interface device can be built using different techniques such as electrical contacts, hall element methods and pressure sensors. The limitations of these methods include inability to function when eating and talking.

The paper presented by Lotte N. S. Andreasen Struijk discusses an innovative inductive tongue computer interface (ITCI) to facilitate tongue-activated commands. This system is based on Faraday’s law of induction for a coil, and uses variable inductance techniques. This system has several advantages over the traditional ones.

This tongue interface device consists of coils connected in serial. The plan is to change the inductance of the coil by introducing ferromagnetic material, attached to the tongue, into the air gap of the coil. The setup is very simple. The coils are connected in serial, and a measured signal is related to all the inductances and the implicit resistance of the coil wire. A current with fixed frequency and fixed amplitude is applied. Based on the number of turns of each coil, it can be determined as to which coil was activated.

A special feature of this device that gives it an edge over traditional methods is that it is partly implantable, due to the activation unit. Activation requires very little force, which means it is faster and less exhausting. In addition, it allows incorporation of as many activation buttons as the number of characters in the alphabet. Another major benefit of ITCS is that it is unaffected by tongue palatal-pressures associated with eating and speaking.

The device can be further developed to enable implantation of the activation unit right under the tongue mucosa. As per the results of a survey done among 26 potential users, 50% of the people were comfortable with the idea of implantation of an activation unit in their tongue. Seven percent were indecisive and 33% were not open to the process of implantation. However, persons who were not willing to go for implantation belonged to the oldest age group (avg. 70 years), and felt they were too old to try this technology. There is also scope for further developing the tongue interface device to facilitate the incorporation of wireless control.