Miniaturized neural implants for localized and controllable drug delivery in the brain

Drug delivery in the brain is challenging due to the existence of the blood brain barrier, which prevents most drugs from entering the target site in the brain. Compared to systematic drug administration, localized and site-specific drug delivery in a minimally invasive manner is effective for the treatment of brain disease. However, its implementation relies on advanced technologies and miniaturized implants/devices for controllable drug delivery. Recent research endeavors have provided a broad range of creative neural implants and platforms for this purpose. In this review, we provide an overview of recent advances in miniaturized neural implants for precise, controllable and minimally invasive drug delivery in the brain. This review will focus on neural implants with proven functionalities by discussing the technologies and materials used to fabricate these miniaturized multi-functional drug delivery implants with either externally connected pumps or integrated microfluidic pumps. The vibrancy of engineering technologies and emerging materials associated with these implants and their significance to targeted and minimally invasive drug delivery for brain disease treatment will motivate continued advance and growth of this area of research.