A speller system for locked-in patient to communicate with friends

Locked-in syndrome (LIS) patient cannot communicate verbally due to complete paralysis of nearly all voluntary muscles in the body. Most of them could move their eyes, of which part of them could move their head. It is very important to establish communication channels for LIS patient. In the current study, we developed a speller system based on detecting the nodding movement. The system is easy to implement because it only requires a laptop which contains digital camera. Results on healthy subjects group showed the proposed speller system could be controlled successfully even without prior training. Then we evaluated its performance on a LIS patient, and 20 correct characters were spelled out within 591 seconds. In conclusion, the proposed speller is suitable for those LIS patient with head movement ability, it could help them to communicate with friends.