Implementation of multi-connected single-channel functional near-infrared spectroscopy system for hyperscanning study

It is not easy to access functional near-infrared spectroscopy (fNIRS) systems for hyperscanning studies because of the cost problems. Accordingly, demands for cost-effective and portable fNIRS systems capable of hyperscanning studies have been growing. To this end, we implemented a wireless fNIRS system with multiple connections based on Bluetooth technology in the present study. The implemented fNIRS system adopted the Bluetooth Low Energy (BLE) protocol enabling lower power consumption and supporting wireless connections between master-slave modules up to seven. The implemented fNIRS system was validated by an experiment composed of typical tasks inducing distinct hemodynamic changes. Task-related hemodynamic changes were collected concurrently from the prefrontal cortex using different slave modules equipped on different participants. Experimental results underpin the fact that different slave modules successfully collected and transferred the data simultaneously and the master module could adequately process the received data.