Imagine you have a special brain-computer interface that allows you to spell words just by thinking about them! But sometimes, using wet electrodes can be awkward and uncomfortable. That’s why scientists created a new system using dry electrodes that provide a more comfortable experience for users. By combining the blinking of the eyes with specific brain signals called SSVEP, they were able to control a speller with amazing accuracy of up to 94.64%! Not only that, but they also designed a unique speller based on the time-space frequency conversion (TSFC) SSVEP paradigm, which allowed users to spell out words in a dry electrode environment. This new system achieved an impressive accuracy rate of 90.18% and an information transmission rate of 117.05 bits per minute. This research shows great promise for improving the usability and performance of brain-computer interfaces and opens up exciting possibilities for future studies using different algorithms to further enhance the system’s capabilities. Curious to know more? Follow the link to explore the full article!

IntroductionSpeller is the best way to express the performance of the brain-computer interface (BCI) paradigm. Due to its advantages of short analysis time and high accuracy, the SSVEP paradigm has been widely used in the BCI speller system based on the wet electrode. It is widely known that the wet electrode operation is cumbersome and that the subjects have a poor experience. In addition, in the asynchronous SSVEP system based on threshold analysis, the system flickers continuously from the beginning to the end of the experiment, which leads to visual fatigue. The dry electrode has a simple operation and provides a comfortable experience for subjects. The EOG signal can avoid the stimulation of SSVEP for a long time, thus reducing fatigue.MethodsThis study first designed the brain-controlled switch based on continuous blinking EOG signal and SSVEP signal to improve the flexibility of the BCI speller. Second, in order to increase the number of speller instructions, we designed the time-space frequency conversion (TSFC) SSVEP stimulus paradigm by constantly changing the time and space frequency of SSVEP sub-stimulus blocks, and designed a speller in a dry electrode environment.ResultsSeven subjects participated and completed the experiments. The results showed that the accuracy of the brain-controlled switch designed in this study was up to 94.64%, and all the subjects could use the speller flexibly. The designed 60-character speller based on the TSFC-SSVEP stimulus paradigm has an accuracy rate of 90.18% and an information transmission rate (ITR) of 117.05 bits/min. All subjects can output the specified characters in a short time.DiscussionThis study designed and implemented a multi-instruction SSVEP speller based on dry electrode. Through the combination of EOG and SSVEP signals, the speller can be flexibly controlled. The frequency of SSVEP stimulation sub-block is recoded in time and space by TSFC-SSVEP stimulation paradigm, which greatly improves the number of output instructions of BCI system in dry electrode environment. This work only uses FBCCA algorithm to test the stimulus paradigm, which requires a long stimulus time. In the future, we will use trained algorithms to study stimulus paradigm to improve its overall performance.

Read Full Article (External Site)