The Continuous Health Analyzing Ring Module (CHARM), recently detailed in a scientific paper, demonstrates how smart rings could one day monitor glucose, lactate, and other biomarkers through sweat rather than optical sensors. But significant limitations remain.
First, it’s worth emphasizing that CHARM is strictly a research project at this stage. Whether the technology will ever make it into a commercial product remains entirely uncertain.
Fundamental barriers persist on several fronts. Its current battery life of around 12 hours is, by most assessments, a relatively minor issue compared with the analytical challenges. Unsurprisingly, peer reviewers raised serious questions about the underlying measurement technology itself, explicitly noting that CHARM requires validation across larger, more diverse cohorts to demonstrate its reliability across a wide range of blood glucose levels and hydration states. Ongoing calibration will also likely remain essential. Both the reviewer comments and responses from lead researcher Professor Joseph Wang are publicly available.
Weighing just 5.1 grams with an outer diameter of 3 centimeters, CHARM continuously tracks four biomarkers. Rather than relying on optical sensors that shine light into subcutaneous blood vessels, the ring analyzes sweat. In principle, the sensor suite can measure glucose, ketones, ascorbic acid (vitamin C), uric acid, lactate, and alcohol. However, to prevent voltage drops, the ring is limited to tracking four parameters at once.
Sweat is sampled passively — without dynamic pumping — using an integrated hydrogel, with the parameters measured electrochemically and processed onboard.
These metrics could prove especially valuable for patients with Type 1 diabetes, where continuous glucose monitoring is critical. Simultaneous ketone monitoring adds further clinical value, potentially enabling early detection of life-threatening diabetic ketoacidosis.
Source: Notebookcheck; Saha, T., Ding, S., Qin, S., et al. “A fully integrated smart ring for daily biochemical monitoring,” Nature Communications (2026)
