Wearable sensors are revolutionizing the tech-world, capable of tracking processes in the body, such as heart rates. They’re even becoming fashionable, with many of them sporting sleek, stylish designs. But wearable sensors also can have applications in detecting threats that are external to the body. Researchers now report in ACS Sensors a first-of-its kind device that can do just that. And to stay fashionable, they’ve designed it as a ring.