The smart ring market, dominated by companies like Oura, Samsung, and RingConn, is about to witness a significant disruption. Circular, a relatively smaller player, is setting new benchmarks with its second-generation smart ring, the Circular Ring 2. Having recently surpassed its $1 million crowdfunding goal, this innovative device promises to deliver a game-changing feature: blood pressure sensing, arriving via an OTA update later this year. Looking ahead, Circular also plans to introduce sensor-driven blood glucose trend analysis in 2026, further solidifying its position as a leader in health-focused wearable technology.
Circular Ring 2 on the finger of a person
Innovative Blood Pressure Measurement Technology
Unlike other wearables relying solely on Photoplethysmography (PPG) sensors, the Circular Ring 2 combines ECG and PPG technologies to provide spot blood pressure measurements. This innovative approach marks a significant advancement, making it the first smart ring to achieve this level of accuracy. The ring’s sensor array measures Pulse Transit Time (PTT) to assess blood pressure. Users can take measurements, ranging from 30 seconds to a couple of minutes, to understand how their activities influence their blood pressure levels.
While the ability of a smart ring to accurately measure blood pressure might sound incredible, especially considering that even tech giants like Apple and Samsung haven’t integrated this functionality natively into their smartwatches, the underlying technology is well-established. It has undergone rigorous clinical testing and is already being commercialized. Notably, Novosound recently unveiled an advanced ultrasound blood pressure monitoring system designed for smartwatches and rings, further validating the feasibility of this technology.
Science-Backed Approach
Front view of the Circular Ring 2
The PTT-based approach employed by the Circular Ring 2 is a scientifically validated, non-invasive, cuffless method for blood pressure measurement. A research paper presented at the 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society highlights this, stating: “It has been reported that the pulse transit time (PTT), the interval between the peak of the R-wave in electrocardiogram (ECG) and the fingertip photoplethysmogram (PPG), is related to arterial stiffness, and can be used to estimate the systolic blood pressure (SBP) and diastolic blood pressure (DBP).” While PTT measurements alone may not be perfectly accurate, incorporating heart rate and other blood pressure estimations significantly reduces the error margin. Further research published in the Hypertension Research journal also supports the efficacy of the PTT method for blood pressure evaluation.
A New Era for Smart Rings
Circular Ring 2 in Gold.
The Circular Ring 2 represents a major leap forward in smart ring technology. Equipped with ECG, PPG, and temperature sensors, it offers comprehensive health tracking, measuring heart rate, blood oxygen saturation, ECG activity, and heart rate variability. Notably, it’s touted as the first FDA-cleared smart ring to offer ECG measurement, including detection of Atrial Fibrillation (AFib), a serious heart condition—a feature previously popularized by Apple Watch.
Currently available on Kickstarter, the Circular Ring 2 is priced at $239 for early backers, with a regular retail price of $549. While positioned at the higher end of the market, the ring offers significant value with no subscription fees and all features accessible out of the box. This innovative device promises to redefine the smart ring landscape and empower users with valuable health insights.
