From Wires and Gels to a Simple Spray
For anyone who’s endured an EEG, the process feels beyond cumbersome. A technician marks a dozen or more points on your scalp, applies sticky gel, and painstakingly glues electrodes to your head. These electrodes connect to a machine via a tangle of wires. The setup is clunky, uncomfortable, and prone to failure as the gel dries out.

Lu and her collaborators wanted something better. They’ve spent years designing tiny sensors, known as electronic tattoos or e-tattoos, which stick to the skin to measure everything from heartbeats to muscle fatigue. But applying these tattoos to the scalp posed a challenge.

“Designing materials that are compatible with hairy skin has been a persistent challenge in e-tattoo technology,” Lu explains.