Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
Rev Sci Instrum. 2024 Aug 1;95(8). doi: 10.1063/5.0187070.
The importance of brain-computer interfaces (BCI) is increasing, and various methods have been developed. Among the developed BCI methods, functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG) are favored due to their non-invasive feature and compact device sizes. EEG monitors the electrical potentials generated by the activation of neurons, and fNIRS monitors the blood flow also generated by neurons, resulting in signals with different properties between the two methods. As the two BCI methods greatly differ in the characteristics of the acquired neural activity signals, for cases of estimating the intention or thought of a subject by BCI, it has been proven that further accurate information may be extracted by utilizing both methods simultaneously. Both systems are powered by electricity, and as EEG systems are greatly sensitive to electrical noises, application of two separate fNIRS and EEG systems together may result in electrical interference as the systems are required to be in contact with the skin and stray currents from the fNIRS system may flow along the surface of the skin into the EEG system. This research proposes a wearable fNIRS-EEG hybrid BCI system, where a single terminal is capable of operating both as a continuous wave fNIRS emitter and as a detector, and also as an EEG electrode. The system has been designed such that the fNIRS and EEG components are electrically separated to avoid electrical interference between each other. It is expected that by utilizing the developed fNIRS-EEG hybrid terminals, the development of BCI analysis may be further accelerated in various fields.
脑机接口 (BCI) 的重要性日益增加，各种方法也相继被开发出来。在已开发的 BCI 方法中，由于其非侵入性和设备小巧的特点，功能性近红外光谱 (fNIRS) 和脑电图 (EEG) 受到青睐。EEG 监测由神经元激活产生的电势能，而 fNIRS 监测也由神经元产生的血流，导致这两种方法的信号具有不同的特性。由于这两种 BCI 方法在获取的神经活动信号的特征上有很大的不同，对于通过 BCI 估计受试者的意图或想法的情况，已经证明通过同时利用这两种方法可以提取更准确的信息。这两个系统都由电供电，由于 EEG 系统对电噪声非常敏感，因此同时应用两个单独的 fNIRS 和 EEG 系统可能会导致电干扰，因为系统需要与皮肤接触，并且 fNIRS 系统的杂散电流可能会沿着皮肤表面流入 EEG 系统。本研究提出了一种可穿戴的 fNIRS-EEG 混合 BCI 系统，其中单个终端既可以作为连续波 fNIRS 发射器和探测器，也可以作为 EEG 电极。该系统的设计使得 fNIRS 和 EEG 组件在电气上相互分离，以避免相互之间的电干扰。预计通过利用开发的 fNIRS-EEG 混合终端，可以在各个领域进一步加速 BCI 分析的发展。
