Conformal in-ear bioelectronics for visual and auditory brain-computer interfaces

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 Spiral, which can adaptively exploit and engage the auditory meatus under electrothermal actuation to enhance information acquisition. Participants achieve offline accuracies of 95% in 2-target steady state visual evoked potential (SSVEP) BCI classification and type target phrases through calibration-free 40-target online SSVEP speller experiment. Interestingly, ear SSVEPs exhibit significant 2nd harmonic frequencies, indicating that in-ear sensing may be complementary for studying harmonic spatial distributions in SSVEP studies. Moreover, ear-pressed auditory classification accuracy can reach 84% in cocktail party experiments. The Spiral provides innovative concepts for designing 3D flexible bioelectronics and assists the development of biomedical engineering and neural monitoring.

Zhouheng Wang, Nanlin Shi, Yingchao Zhang, Ning Zheng, Haicheng Li, Yang Jiao, Jiahui Cheng, Yutong Wang, Xiaoqing Zhang, Ying Chen, Yihao Chen, Heliang Wang, Tao Xie, Yijun Wang, Yinji Ma, Xiaorong Gao, Xue Feng