Christina Tringides

Christina Tringides, 31, built a new type of electrocorticogram—a thin gadget that sits directly on the brain during an invasive procedure, like the removal of a tumor or tissue responsible for epilepsy, and records its electrical activity. These devices help surgeons determine what to remove and what to keep: If they are too aggressive with a tumor, for example, they might extract brain tissue that’s responsible for movement or speech.

Today’s versions consist of metal electrodes attached to a sheath of plastic. They are stiff, but the brain is soft; Tringides likens them to a spatula placed on top of tofu. “It doesn’t conform to the contours of the brain the way surgeons would like it to,” she says. That mismatch reduces the device’s accuracy and can damage underlying neurons.

To improve the devices, Tringides turned to hydrogels, a class of polymers that, like the brain, exhibit properties of both liquids and solids. By tinkering with a hydrogel derived from alginate, a substance that naturally occurs in seaweed, she created a film that closely matches the brain’s mechanical properties and could thus adhere to its geometry in ways that current devices cannot. She then embedded spaghetti-like electrodes made from carbon nanotubes and flakes of graphene, a conductive form of carbon that can easily bend and flex, into the gadget. Her prototype has been used to record and map signals emitted by the brains of rats—including the hard-to-reach auditory cortex, responsible for hearing, which required it to bend more than 180 degrees.