A Versatile In-Ear Biosensing System and Body-Area Network for Unobtrusive Continuous Health Monitoring

• Published in: IEEE transactions on biomedical circuits and systems Vol. 17; no. 3; pp. 1 - 12
• Main Authors: Paul, Akshay, Lee, Min S., Xu, Yuchen, Deiss, Stephen R., Cauwenberghs, Gert
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.06.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Accelerometers; BCI; Biosensors; Body area networks; body sensor network; Channels; Circuit boards; Data acquisition; Data storage; Data transmission; dry electrodes; Ear; EEG; Electrodes; Electroencephalography; Electromyography; Electrophysiology; EMG; EOG; Eye Movements; Forehead; health sensing; Humans; in-ear EEG; Iron; Jaw; Monitoring; Muscles; Noise levels; PCB electrodes; Printed circuits; Sensors; Telemedicine; WiFi; Wireless communication; Wireless sensor networks
• ISSN: 1932-4545; 1940-9990; 1940-9990
• DOI: 10.1109/TBCAS.2023.3272649

To enable continuous, mobile health monitoring, body-worn sensors need to offer comparable performance to clinical devices in a lightweight, unobtrusive package. This work presents a complete versatile wireless electrophysiology data acquisition system (weDAQ) that is demonstrated for in-ear electroencephalography (EEG) and other on-body electrophysiology with user-generic dry-contact electrodes made from standard printed circuit boards (PCBs). Each weDAQ device provides 16 recording channels, driven right leg (DRL), a 3-axis accelerometer, local data storage, and adaptable data transmission modes. The weDAQ wireless interface supports deployment of a body area network (BAN) capable of aggregating various biosignal streams over multiple worn devices simultaneously, on the 802.11n WiFi protocol. Each channel resolves biopotentials ranging over 5 orders of magnitude with a noise level of 0.52 <inline-formula><tex-math notation="LaTeX">\mathrm{\upmu }\mathrm{V}</tex-math></inline-formula><inline-formula><tex-math notation="LaTeX">\mathrm{_{rms}}</tex-math></inline-formula> over a 1000-Hz bandwidth, and a peak SNDR of 119 dB and CMRR of 111 dB at 2 ksps. The device leverages in-band impedance scanning and an input multiplexer to dynamically select good skin contacting electrodes for reference and sensing channels. In-ear and forehead EEG measurements taken from subjects captured modulation of alpha brain activity, electrooculogram (EOG) characteristic eye movements, and electromyogram (EMG) from jaw muscles. Simultaneous ECG and EMG measurements were demonstrated on multiple, freely-moving subjects in their natural office environment during periods of rest and exercise. The small footprint, performance, and configurability of the open-source weDAQ platform and scalable PCB electrodes presented, aim to provide the biosensing community greater experimental flexibility and lower the barrier to entry for new health monitoring research.