RAIJIN

Low-cost electroencephalographic (EEG) systems have been available for over a decade, such as the open hardware OpenBCI ecosystem. While EEG has been democratized to varying degrees, blood-oxygen-level-dependent (BOLD) methodologies are constrained to medical and niche realms. While magnetic resonance imaging is impractical for a hobbyist, functional near-infrared spectroscopy (fNIRS) may offer a more practical alternative. Similarly, non-visual and non-auditory feedback from a brain-computer interface (BCI) may be streamlined with a tactile or haptic device. Transcranial temporal interference stimulation (TTIS) can be directed and integrated with the existing ecosystem. The Rank-Adjusted Infrared Juxtaposed Interferential Neuromodulation (RAIJIN) marks three components that would significantly improve tools for citizen-scientists. Given recent low-cost projects, it may be possible to bring low-cost fNIRS, non-invasive deep brain stimulation, and tactile response into the OpenBCI ecosystem. Tactile and TTIS enable closed-loop computer-brain interference (CBI). By integrating BCI and CBI, the RAIJIN system will enable mobile, low-cost, BOLD-capable, closed loop, and non-invasive brain-to-brain interface (BBI).