{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,6]],"date-time":"2025-12-06T17:11:23Z","timestamp":1765041083613,"version":"build-2065373602"},"reference-count":48,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2020,7,28]],"date-time":"2020-07-28T00:00:00Z","timestamp":1595894400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["2017YFB1300300"],"award-info":[{"award-number":["2017YFB1300300"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["81925020, 61976152, 81671861"],"award-info":[{"award-number":["81925020, 61976152, 81671861"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Young Elite Scientist Sponsorship Program by CAST","award":["2018QNRC001"],"award-info":[{"award-number":["2018QNRC001"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The brain\u2013computer interface (BCI) spellers based on steady-state visual evoked potentials (SSVEPs) have recently been widely investigated for their high information transfer rates (ITRs). This paper aims to improve the practicability of the SSVEP-BCIs for high-speed spelling. The system acquired the electroencephalogram (EEG) data from a self-developed dedicated EEG device and the stimulation was arranged as a keyboard. The task-related component analysis (TRCA) spatial filter was modified (mTRCA) for target classification and showed significantly higher performance compared with the original TRCA in the offline analysis. In the online system, the dynamic stopping (DS) strategy based on Bayesian posterior probability was utilized to realize alterable stimulating time. In addition, the temporal filtering process and the programs were optimized to facilitate the online DS operation. Notably, the online ITR reached 330.4 \u00b1 45.4 bits\/min on average, which is significantly higher than that of fixed stopping (FS) strategy, and the peak value of 420.2 bits\/min is the highest online spelling ITR with a SSVEP-BCI up to now. The proposed system with portable EEG acquisition, friendly interaction, and alterable time of command output provides more flexibility for SSVEP-based BCIs and is promising for practical high-speed spelling.<\/jats:p>","DOI":"10.3390\/s20154186","type":"journal-article","created":{"date-parts":[[2020,7,28]],"date-time":"2020-07-28T10:16:49Z","timestamp":1595931409000},"page":"4186","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":26,"title":["Optimizing SSVEP-Based BCI System towards Practical High-Speed Spelling"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4439-1328","authenticated-orcid":false,"given":"Jiabei","family":"Tang","sequence":"first","affiliation":[{"name":"Lab of Neural Engineering &amp; Rehabilitation, Department of Biomedical Engineering, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Minpeng","family":"Xu","sequence":"additional","affiliation":[{"name":"Lab of Neural Engineering &amp; Rehabilitation, Department of Biomedical Engineering, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China"},{"name":"Tianjin International Joint Research Center for Neural Engineering, Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin 300072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6912-1738","authenticated-orcid":false,"given":"Jin","family":"Han","sequence":"additional","affiliation":[{"name":"Lab of Neural Engineering &amp; Rehabilitation, Department of Biomedical Engineering, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Miao","family":"Liu","sequence":"additional","affiliation":[{"name":"Tianjin International Joint Research Center for Neural Engineering, Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin 300072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tingfei","family":"Dai","sequence":"additional","affiliation":[{"name":"Lab of Neural Engineering &amp; Rehabilitation, Department of Biomedical Engineering, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shanguang","family":"Chen","sequence":"additional","affiliation":[{"name":"Lab of Neural Engineering &amp; Rehabilitation, Department of Biomedical Engineering, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China"},{"name":"Tianjin International Joint Research Center for Neural Engineering, Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin 300072, China"},{"name":"National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, Beijing 100094, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dong","family":"Ming","sequence":"additional","affiliation":[{"name":"Lab of Neural Engineering &amp; Rehabilitation, Department of Biomedical Engineering, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China"},{"name":"Tianjin International Joint Research Center for Neural Engineering, Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin 300072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,7,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1145\/1941487.1941506","article-title":"Brain-Computer Interfaces for Communication and Control","volume":"54","author":"McFarland","year":"2011","journal-title":"Commun. ACM"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Wolpaw, J., and Wolpaw, E.W. (2012). Brain-Computer Interfaces: Principles and Practice, Oxford University Press.","DOI":"10.1093\/acprof:oso\/9780195388855.001.0001"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"780","DOI":"10.1109\/TNSRE.2019.2903685","article-title":"BCI Monitor Enhances Electroencephalographic and Cerebral Hemodynamic Activations During Motor Training","volume":"27","author":"Wang","year":"2019","journal-title":"IEEE Trans. Neural. Syst. Rehabil. Eng."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Chen, S., Jiang, J., Tang, J., Jiao, X., Qi, H., Cao, Y., Wang, C., and Ming, D. (2017). An Experimental Study on Usability of Brain-Computer Interaction Technology in Human Spaceflight, Springer International Publishing.","DOI":"10.1007\/978-3-319-58625-0_22"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"527","DOI":"10.1007\/s00779-010-0322-8","article-title":"Brain\u2013computer interfaces for space applications","volume":"15","author":"Broschart","year":"2011","journal-title":"Pers. Ubiquitous Comput."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2266","DOI":"10.1109\/TBME.2019.2958641","article-title":"Discriminative canonical pattern matching for single-trial classification of ERP components","volume":"67","author":"Xiao","year":"2019","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1166","DOI":"10.1109\/TBME.2018.2799661","article-title":"A Brain-Computer Interface Based on Miniature-Event-Related Potentials Induced by Very Small Lateral Visual Stimuli","volume":"65","author":"Xu","year":"2018","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"16066","DOI":"10.1088\/1741-2552\/ab4dc6","article-title":"An online SSVEP-BCI system in an optical see-through augmented reality environment","volume":"17","author":"Ke","year":"2020","journal-title":"J. Neural. Eng."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1450019","DOI":"10.1142\/S0129065714500191","article-title":"A high-speed brain speller using steady-state visual evoked potentials","volume":"24","author":"Nakanishi","year":"2014","journal-title":"Int. J. Neural Syst."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"103","DOI":"10.3389\/fnhum.2020.00103","article-title":"Cross-Dataset Variability Problem in EEG Decoding with Deep Learning","volume":"14","author":"Xu","year":"2020","journal-title":"Front. Hum. Neurosci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"16033","DOI":"10.1088\/1741-2552\/ab598f","article-title":"Enhance decoding of pre-movement EEG patterns for brain\u2013computer interfaces","volume":"17","author":"Wang","year":"2020","journal-title":"J. Neural. Eng."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"418","DOI":"10.1016\/j.pneurobio.2009.11.005","article-title":"Steady-state visually evoked potentials: Focus on essential paradigms and future perspectives","volume":"90","author":"Vialatte","year":"2010","journal-title":"Prog. Neurobiol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"204","DOI":"10.1016\/j.neuroimage.2016.03.073","article-title":"Use of a steady-state baseline to address evoked vs. oscillation models of visual evoked potential origin","volume":"134","author":"Xu","year":"2016","journal-title":"Neuroimage"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2831","DOI":"10.1109\/TBME.2013.2265260","article-title":"SSVEP-Based Brain\u2013Computer Interfaces Using FSK-Modulated Visual Stimuli","volume":"60","author":"Kimura","year":"2013","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"66009","DOI":"10.1088\/1741-2560\/10\/6\/066009","article-title":"Brain\u2013computer interface based on intermodulation frequency","volume":"10","author":"Chen","year":"2013","journal-title":"J. Neural. Eng."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Xu, M., Han, J., Wang, Y., Jung, T., and Ming, D. (2020). Implementing over 100 command codes for a high-speed hybrid brain-computer interface using concurrent P300 and SSVEP features. IEEE Trans. Biomed. Eng., 1.","DOI":"10.1109\/TBME.2020.2975614"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"26014","DOI":"10.1088\/1741-2560\/11\/2\/026014","article-title":"A visual parallel-BCI speller based on the time\u2013frequency coding strategy","volume":"11","author":"Xu","year":"2014","journal-title":"J. Neural. Eng."},{"key":"ref_18","unstructured":"Chen, X., Wang, Y., Nakanishi, M., Jung, T.-P., and Gao, X. (2014, January 26\u201330). Hybrid Frequency and Phase Coding for a High-Speed SSVEP-Based BCI Speller. Proceedings of the 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Chicago, IL, USA."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Wong, C.M., Wang, B., Wang, Z., Lao, K.F., Rosa, A., and Wan, F. (2020). Spatial Filtering in SSVEP-based BCIs: Unified Framework and New Improvements. IEEE Trans. Biomed. Eng.","DOI":"10.1109\/TBME.2020.2975552"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2610","DOI":"10.1109\/TBME.2006.886577","article-title":"Frequency recognition based on canonical correlation analysis for SSVEP-based BCIs","volume":"53","author":"Lin","year":"2006","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"E6058","DOI":"10.1073\/pnas.1508080112","article-title":"High-speed spelling with a noninvasive brain\u2013computer interface","volume":"112","author":"Chen","year":"2015","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"46008","DOI":"10.1088\/1741-2560\/12\/4\/046008","article-title":"Filter bank canonical correlation analysis for implementing a high-speed SSVEP-based brain\u2013computer interface","volume":"12","author":"Chen","year":"2015","journal-title":"J. Neural. Eng."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1016\/j.jneumeth.2013.07.018","article-title":"Multivariate synchronization index for frequency recognition of SSVEP-based brain\u2013computer interface","volume":"221","author":"Zhang","year":"2014","journal-title":"J. Neurosci. Methods"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"262","DOI":"10.26599\/TST.2018.9010010","article-title":"Boosting the information transfer rate of an SSVEP-BCI system using maximal-phase-locking value and minimal-distance spatial filter banks","volume":"24","author":"Lin","year":"2019","journal-title":"Tsinghua Sci. Technol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1109\/TBME.2017.2694818","article-title":"Enhancing Detection of SSVEPs for a high-speed brain speller using task-related component analysis","volume":"65","author":"Nakanishi","year":"2018","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"36025","DOI":"10.1088\/1741-2560\/10\/3\/036025","article-title":"Optimizing event-related potential based brain-computer interfaces: A systematic evaluation of dynamic stopping methods","volume":"10","author":"Schreuder","year":"2013","journal-title":"J. Neural. Eng."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1016\/j.rehab.2014.10.006","article-title":"Improving BCI performance through co-adaptation: Applications to the P300-speller","volume":"58","author":"Mattout","year":"2015","journal-title":"Ann. Phys. Rehabil. Med."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1447","DOI":"10.1109\/TBME.2014.2320948","article-title":"A dynamically optimized SSVEP brain-computer interface (BCI) speller","volume":"62","author":"Yin","year":"2014","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Nakanishi, M., Wang, Y., Wang, Y., and Jung, T. (2015, January 25\u201329). A dynamic stopping method for improving performance of steady-state visual evoked potential based brain-computer interfaces. Proceedings of the 2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Milan, Italy.","DOI":"10.1109\/EMBC.2015.7318547"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"46025","DOI":"10.1088\/1741-2552\/aac605","article-title":"Incorporation of dynamic stopping strategy into the high-speed SSVEP-based BCIs","volume":"15","author":"Jiang","year":"2018","journal-title":"J. Neural. Eng."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1057","DOI":"10.1049\/el.2010.0923","article-title":"Visual stimulus design for high-rate SSVEP BCI","volume":"46","author":"Wang","year":"2010","journal-title":"Electron. Lett."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"433","DOI":"10.1163\/156856897X00357","article-title":"The psychophysics toolbox","volume":"10","author":"Brainard","year":"1997","journal-title":"Spat. Vis."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"16026","DOI":"10.1088\/1741-2552\/ab2373","article-title":"Learning across multi-stimulus enhances target recognition methods in SSVEP-based BCIs","volume":"17","author":"Wong","year":"2020","journal-title":"J. Neural. Eng."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"16013","DOI":"10.1088\/1741-2560\/12\/1\/016013","article-title":"Increasing BCI communication rates with dynamic stopping towards more practical use: An ALS study","volume":"12","author":"Mainsah","year":"2015","journal-title":"J. Neural. Eng."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1109\/7333.918276","article-title":"Rapid prototyping of an EEG-based brain-computer interface (BCI)","volume":"9","author":"Guger","year":"2001","journal-title":"IEEE Trans. Neural. Syst. Rehabil. Eng."},{"key":"ref_36","unstructured":"Oppenheim, A.V., Schafer, R.W., and Buck, J.R. (1999). Discrete-Time Signal Processing, Prentice-Hall, Inc.. [2nd ed.]."},{"key":"ref_37","unstructured":"Howell, D.C. (2012). Statistical Methods for Psychology, Cengage Learning."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1746","DOI":"10.1109\/TNSRE.2016.2627556","article-title":"A Benchmark Dataset for SSVEP-Based Brain\u2013Computer Interfaces","volume":"25","author":"Wang","year":"2017","journal-title":"IEEE Trans. Neural. Syst. Rehabil. Eng."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"2425","DOI":"10.1109\/78.97998","article-title":"A technique for realizing linear phase IIR filters","volume":"39","author":"Powell","year":"1991","journal-title":"IEEE Trans. Signal. Process."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"988","DOI":"10.1109\/78.492552","article-title":"Determining the initial states in forward-backward filtering","volume":"44","author":"Gustafsson","year":"1996","journal-title":"IEEE Trans. Signal. Process."},{"key":"ref_41","first-page":"14","article-title":"Optimisation of the Transient response of a Digital Filter","volume":"9","author":"Sadovsky","year":"2000","journal-title":"Radioengineering"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"508","DOI":"10.1109\/TNSRE.2013.2253125","article-title":"Bayesian approach to dynamically controlling data collection in P300 spellers","volume":"21","author":"Throckmorton","year":"2013","journal-title":"IEEE Trans. Neural. Syst. Rehabil. Eng."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"35005","DOI":"10.1088\/1741-2560\/11\/3\/035005","article-title":"Integrating dynamic stopping, transfer learning and language models in an adaptive zero-training ERP speller","volume":"11","author":"Kindermans","year":"2014","journal-title":"J. Neural. Eng."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Chaudhary, U., Mrachacz-Kersting, N., and Birbaumer, N. (2020). Neuropsychological and neurophysiological aspects of brain-computer-interface (BCI) control in paralysis. J. Physiol., Added Added Added.","DOI":"10.1113\/JP278775"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"329","DOI":"10.1016\/B978-0-444-63934-9.00024-X","article-title":"Chapter 24\u2014Ethics and the emergence of brain-computer interface medicine","volume":"Volume 168","author":"Ramsey","year":"2020","journal-title":"Handbook of Clinical Neurology"},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"K\u00f6gel, J., Jox, R.J., and Friedrich, O. (2020). What is it like to use a BCI?\u2014Insights from an interview study with brain-computer interface users. BMC Med. Ethics, 21.","DOI":"10.1186\/s12910-019-0442-2"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"3","DOI":"10.3384\/de-ethica.2001-8819.20613","article-title":"Moral agency without responsibility? Analysis of three ethical models of human-computer interaction in times of artificial intelligence (AI)","volume":"6","author":"Alexis","year":"2020","journal-title":"De Ethica"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1130","DOI":"10.3389\/fpsyg.2020.01130","article-title":"People Copy the Actions of Artificial Intelligence","volume":"11","author":"Klichowski","year":"2020","journal-title":"Front. Psychol."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/15\/4186\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T09:52:16Z","timestamp":1760176336000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/15\/4186"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,7,28]]},"references-count":48,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2020,8]]}},"alternative-id":["s20154186"],"URL":"https:\/\/doi.org\/10.3390\/s20154186","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2020,7,28]]}}}