Underwater movement sensor can sound the alarm when a swimmer might be drowning

Many flexible fitness trackers can't be submerged in water because the coatings required to completely seal these devices would make them uncomfortable to wear. Now, researchers reporting in ACS Nano have applied a thin, slippery coating to conductive fabric, creating a breathable underwater movement sensor. They integrated the sensor into a smart device that wirelessly alerts a smartphone app when a swimmer stops moving, an indication that they could be drowning.