This article outlined the evolution of brain machine interfaces from one-way electrical read-outs to bidirectional biomimetic systems that are able to both decode neural activity as well as deliver feedback. This shift involves three improvements: signal modality, hardware morphology, and system architecture. First, there was a switch from electrophysiology to integrated electrochemical sensing that captures both fast spikes and slow neuromodulators. Next, in terms of hardware, the rigid silicon was switched to soft, tissue matched electrodes that improve biocompatibility and increase longevity. Finally, in terms of architecture, there was a switch from passive monitors to closed-loop, neuromorphic controllers that modulate the simulation in real time.