Brain implants are limited right now -- they typically measure just one thing at a time, and their stiff wiring can wreck tissue if the device stays in place for long enough. Neither of those problems will matter if MIT's flexible fiber implant becomes a practical reality, though. The school's researchers have developed very thin (almost nanoscale), flexible polymer fibers that have customizable channels for carrying chemicals, electricity and light. These strands could not only treat a patient with drugs and light stimulation, but measure the response with electrodes; you'd know whether or not your medicine is working. The bendy, unintrusive design should also be safe for your body, making it possible to tackle long-term illnesses.