Many disorders of learning, memory, and motor control are caused by abnormal amounts of glutamate, a neurotransmitter in the brain. If glutamate concentrations could be accurately monitored, surgeons could find and remove cells that poorly regulate glutamate levels. So a team led by University of Kentucky neurobiologist Greg Gerhardt has developed microsensors that track the concentration of glutamate quickly enough-and in enough locations simultaneously-to aid in such surgeries. Each sensor consists of at least two recording patches of platinum, coated with an enzyme and polymers, on the end of a ceramic probe five micrometers wide. The coating reacts with the glutamate, creating an electric current proportional to the glutamate concentration. The sensors work on a second-by-second basis, unlike existing devices that take tens of seconds to register changes, says Gerhardt. Placed in an epileptic patient’s brain for the duration of surgery, a 60-micrometer-by-700-micrometer array of the sensors could pinpoint the smallest region of tissue that needs to be removed. Gerhardt plans to mass-produce the sensors in about two years at his company, Quanteon, in Lexington, KY.