Real-time in vivo analysis of neurochemical dynamics has great physiological and pathological implications for a full understanding of the brain. Self-powered electrochemical systems (SPESs) built on galvanic cell configurations bear the advantages of easy miniaturization for implantation and no interference to electric activities of neurons over traditional externally-powered electrochemical sensors for self-triggered in vivo analysis. However, this is still a new concept for in vivo neurochemical sensing with few implanted examples reported so far. This tutorial review summarizes the development of SPESs toward implantable applications from both principal and practical perspectives, ultimately aimed at providing a guide map to the future design of neurochemical sensors for in vivo analysis of brain chemistry.