Technical Note: A Low-Cost Research Platform for Brain-Computer-Interface Applications in Mixed Reality

Many brain-computer-interface (BCI) approaches, such as the steady-state-visually-evoked-potential (SSVEP) and BCI speller paradigms, rely on evoking neural signals using presentation of audiovisual stimuli. These exogenous BCIs typically involve the user staring at a physical stimulus presentation apparatus resulting in prolonged system setup and degraded portability. We present a research platform for BCI implementations in mixed reality (XR) environments, enabling less-invasive holographic stimulus presentation and greatly enhanced portability at low-cost. The platform consists of a 3D-printable electroencephalography (EEG) attachment for the Microsoft HoloLens, firmware for the OpenBCI Cyton EEG amplifier evaluation kit, and Unity software supporting direct Bluetooth low-energy communication between the EEG device and the HoloLens. The platform allows researchers and hobbyists to prototype BCIs with an easy to don/doff EEG attachment for the HoloLens that is capable of recording high-quality EEG using dry electrodes in an untethered XR environment without the need for external compute resources.