Wearable sensors on the face are invisible to the eye

TL;DR - A Nature item reports imperceptible face-worn electrodes that can record brain waves and other biosignals while remaining invisible and unfeelable to the wearer. It matters as a step toward unobtrusive, always-on physiological and neural sensing.

• Describes skin-mounted electrodes on the face that measure brain waves (and "more"), implying multi-signal biosensing (likely EEG plus other electrophysiological readings).
• Key claimed advance is form factor: the sensors "cannot be seen or felt," pointing to ultrathin, conformal, transparent wearable materials.
• Such invisible, comfortable sensors could enable continuous real-world monitoring and richer input streams for brain–computer interfaces and health tracking.
• Content is thin (a Nature headline/abstract only): no device specs, materials, accuracy, or study results are provided, so technical details are inferred rather than reported.