Design of a Compact Wireless EEG Recorder With Extra-High Sampling Rate and Precise Time Synchronization for Auditory Brainstem Response

This paper proposed a compact wearable Electroencephalography (EEG) acquisition and analysis system targeting for event-related, wide-bandwidth biopotentials including Auditory Brainstem Response (ABR). The proposed system enables a 2-channel high EEG sampling mode with a sampling rate up to 16kHz, and an 8-channel low EEG sampling mode with a sampling rate of 4kHz. An audio codec is integrated generating synchronized audio stimulation and potential audio recording. A Bluetooth 5 based in-the-air protocol is designed featuring lossless neural data compression algorithm and lost-packet-retransmission strategy. Hydrogels are used as the tissue interface on the electrodes to improve the conductivity and stability. A precise time synchronization method with a standard deviation of
$0.07\mu \text{s}$
is implemented for timestamping when external stimulus is requested. A Graphic User Interface (GUI) is developed for remote control of the proposed device as well as for real-time display of the acquired neural signal and analysis results. Both bench test and in-vivo click-ABRs test on human subject were performed on the proposed device. The experimental results proved the ability of the proposed EEG recorder to acquire high-time-resolution ABRs while giving periodic auditory stimulation.