Contemporary smart rings like the Oura Ring 5 or the Samsung Galaxy Ring can offer a wealth of insights into heart health and sleep, but they’re still largely limited by what their optical sensors can track. The prototype ring the researchers created, dubbed the Continuous Health Analyzing Ring Module (CHARM) in the paper, clamps around a person’s finger and wirelessly shares data with a smartphone. Rather than invasively drawing blood or forcing the wearer to work out to produce sweat, the ring uses an osmotic hydrogel that relies on the principles of osmosis to naturally draw sweat out. Continuous glucose and ketone monitoring may also help with determining optimal insulin dosage, especially for diabetics. Still, the idea of a future smart ring combining existing biophysical sensors with new chemical ones is intriguing, especially while cracking noninvasive glucose monitoring remains a top goal for wearable makers.