Understanding brain function through large-scale brain-computer interfaces (BCIs) is essential for deciphering neural dynamics, treating neurological disorders, and developing advanced neuroprosthetics. A major challenge in the field is achieving simultaneous, large-scale, stable recording of neural activity with single-cell resolution, millisecond precision, and cell-type specificity across three-dimensional (3D) brain tissue throughout development, learning, and aging. In this talk, Harvard University’s Jia Liu will introduce a suite of soft and flexible bioelectronic technologies engineered to address this challenge in brain-computer interfaces.