Conformal in-ear bioelectronics for visual and auditory brain-computer interfaces
Zhouheng Wang, Nanlin Shi, Yingchao Zhang, Ning Zheng, Haicheng Li, Yang Jiao, Jiahui Cheng, Yutong Wang, Xiaoqing Zhang, Ying Chen, Yihao Chen, Heling Wang, Tao Xie, Yijun Wang, Yinji Ma, Xiaorong Gao, Xue Feng
Abstract
Abstract Brain-computer interfaces (BCIs) have attracted considerable attention in motor and language rehabilitation. Most devices use cap-based non-invasive, headband-based commercial products or microneedle-based invasive approaches, which are constrained for inconvenience, limited applications, inflammation risks and even irreversible damage to soft tissues. Here, we propose in-ear visual and auditory BCIs based on in-ear bioelectronics, named as SpiralE, which can adaptively expand and spiral along the auditory meatus under electrothermal actuation to ensure conformal contact. Participants achieve offline accuracies of 95% in 9-target steady state visual evoked potential (SSVEP) BCI classification and type target phrases successfully in a calibration-free 40-target online SSVEP speller experiment. Interestingly, in-ear SSVEPs exhibit significant 2 nd harmonic tendencies, indicating that in-ear sensing may be complementary for studying harmonic spatial distributions in SSVEP studies. Moreover, natural speech auditory classification accuracy can reach 84% in cocktail party experiments. The SpiralE provides innovative concepts for designing 3D flexible bioelectronics and assists the development of biomedical engineering and neural monitoring.