The NeuroString probe in a mouse colon. (Credit: Jinxing Li/Bao lab, Stanford)

A new string-like implant can monitor fluctuations in brain chemicals, like a fitness tracker for the brain.

Imbalances in brain chemistry are at the heart of many neurologic diseases. These same brain chemicals also play roles in gut health. So, scientists at Stanford invented “NeuroString” — a soft implantable probe that can interface seamlessly with both brain and gut tissue. It has potential applications in depression, Parkinson’s disease, and intestinal diseases.

The probe is made of graphene. The team used a laser to engrave what the researchers describe as a “hairy entangled network of graphene” into a plastic. The plastic contains molecules that turn into nanoparticle dots on the surface of graphene that can improve the sensitivity and selectivity for simultaneous measurement of dopamine and serotonin. They then embedded the network in a rubber matrix.

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