Motion artifact–controlled micro–brain sensors between hair follicles for persistent augmented reality brain–computer interfaces

H Hodam Kim (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) J Ju Hyeon Kim (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) Y Yoon Jae Lee (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) J Jimin Lee H Hyojeong Han (Department of Biomedical Engineering, Hanyang University) H Hoon Yi (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) H Hyeonseok Kim (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) H Hojoong Kim (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) T Tae Woog Kang (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) S Suyeong Chung (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) S Seunghyeb Ban (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) B Byeongjun Lee (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) H Haran Lee (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology) C Chang-Hwan Im (Department of Biomedical Engineering, Hanyang University) S Seong J. Cho (Department of Mechanical Engineering, Chungnam National University) J Jung Woo Sohn (School of Mechanical System Engineering, Kumoh National Institute of Technology) K Ki Jun Yu (Functional Bio-integrated Electronics and Energy Management Laboratory, School of Electrical and Electronic Engineering, Yonsei University) T Tae June Kang (Department of Mechanical Engineering, Inha University) W Woon-Hong Yeo (Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology)

Abstract

Modern brain–computer interfaces (BCI), utilizing electroencephalograms for bidirectional human–machine communication, face significant limitations from movement-vulnerable rigid sensors, inconsistent skin–electrode impedance, and bulky electronics, diminishing the system’s continuous use and portability. Here, we introduce motion artifact–controlled micro–brain sensors between hair strands, enabling ultralow impedance density on skin contact for long-term usable, persistent BCI with augmented reality (AR). An array of low-profile microstructured electrodes with a highly conductive polymer is seamlessly inserted into the space between hair follicles, offering high-fidelity neural signal capture for up to 12 h while maintaining the lowest contact impedance density (0.03 kΩ·cm −2 ) among reported articles. Implemented wireless BCI, detecting steady-state visually evoked potentials, offers 96.4% accuracy in signal classification with a train-free algorithm even during the subject’s excessive motions, including standing, walking, and running. A demonstration captures this system’s capability, showing AR-based video calling with hands-free controls using brain signals, transforming digital communication. Collectively, this research highlights the pivotal role of integrated sensors and flexible electronics technology in advancing BCI’s applications for interactive digital environments.

Article Details

Volume / Issue Vol. 122, Issue 15
Published April 15, 2025
ISSN 0027-8424
Publisher National Academy of Sciences

Authors (19)

H

Hodam Kim

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

J

Ju Hyeon Kim

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

Y

Yoon Jae Lee

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

J

Jimin Lee

H

Hyojeong Han

Department of Biomedical Engineering, Hanyang University

H

Hoon Yi

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

H

Hyeonseok Kim

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

H

Hojoong Kim

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

T

Tae Woog Kang

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

S

Suyeong Chung

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

S

Seunghyeb Ban

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

B

Byeongjun Lee

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

H

Haran Lee

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology

C

Chang-Hwan Im

Department of Biomedical Engineering, Hanyang University

S

Seong J. Cho

Department of Mechanical Engineering, Chungnam National University

J

Jung Woo Sohn

School of Mechanical System Engineering, Kumoh National Institute of Technology

K

Ki Jun Yu

Functional Bio-integrated Electronics and Energy Management Laboratory, School of Electrical and Electronic Engineering, Yonsei University

T

Tae June Kang

Department of Mechanical Engineering, Inha University

W

Woon-Hong Yeo

Wearable Intelligent Systems and Healthcare Center, Institute for Matter and Systems, Georgia Institute of Technology