Researchers have developed the first biocompatible internal-ion-gated organic electrochemical transistor (IGT) that is fast enough to enable real-time signal sensing and stimulation of brain signals. The IGT provides a miniaturized, soft, conformable interface with human skin, using local amplification to record high quality neural signals, suitable for advanced data processing. This could lead to safer, smaller, and smarter bioelectronic devices that can be implanted in humans over long periods of time.