The goal of this clinical trial is to evaluate how accurately the CART-I plus developed by Sky Labs can measure blood pressure. The primary endpoint of this clinical trial is accuracy (mmHg) of 'CART-I plus' which is obtained by calculating mean error and standard deviation of blood pressure differences between 'CART-I plus' and the gold standard for non-invasive method, auscultatory method. The reference readings are taken by auscultatory method using a sphygmomanometer and a stethoscope. The mean errors and standard deviations are calculated both sample- and subject-wise.

According to the World Health Organization (WHO), hypertension is one of the major risk factors for death worldwide. The global adult population with hypertension is approximately 113 million, with an estimated prevalence of 18-27%. Hypertension is associated with stroke and other cardiovascular diseases, thus early detection and treatment critical. National guidelines of the Japanese, European, and American Hypertension Society recommend that home blood pressure and clinic blood pressure test results be applied together when diagnosing hypertension, emphasizing the importance of blood pressure monitoring in daily life. In addition, according to the Ohasama cohort study and the Finn-Home study, blood pressure measured in daily life was more predictive of cardiovascular disease than the office blood pressure.

There are invasive and non-invasive methods for blood pressure monitoring. The invasive method measures blood pressure using a pressure sensor by inserting a catheter into a blood vessel, and the non-invasive method measures blood pressure by sensing sound or vibration while applying pressure using a cuff. Invasive blood pressure tests can continuously measure blood pressure and are accurate, but there is a high risk of side effects such as distal ischemia, bleeding, thrombosis, infection, etc and is not available for a daily life. Non-invasive blood pressure test methods such as auscultatory measurement and oscillometric method are simpler than invasive methods, but it has limitations in measuring blood pressure continuously and observing long-term variations.

The photoplethysmography (PPG) method makes it possible to measure blood pressure without a cuff, enabling people to check and monitor blood pressure in daily life for a long time. It has been reported that the wavelength and amplitude of the PDW signal collected from the finger show a high correlation (0.92) with the PDP signal collected from the wrist. This suggests that the blood pressure accuracy of measuring blood pressure with PPG signals collected from the finger will not differ significantly from that measured from the wrist.

Sky Labs has developed 'CART-I plus' that can measure blood pressure in daily life without a cuff. 'CART-I plus' is a ring-type device that applies the principle of PPG technology to measure blood flow through finger veins. This clinical trial was designed in accordance with the ISO 81060-2:2018 standard to evaluate the accuracy of blood pressure estimated by 'CART-I plus'.

Inclusion Criteria:

• Those aged 19 or older
• Those who voluntarily decided to participate in this clinical trial and gave written consent to the subject explanation and consent form
• Those who is willing to comply with the clinical trial protocol

Exclusion Criteria:

• Those whose sound of fifth Kortkoff phase (K5) is not heard during blood pressure test using an auscultation type sphygmomanometer
• Those with unstable cardiac condition (myocardial infarction, ventricular arrhythmia, atrial fibrillation, premature ventricular contraction, pulmonary embolism 1 week before screening date)
• Those with arm circumference greater than 42 cm (> 42 cm)
• Those with a history of hypersensitivity to clinical trial medical device raw materials (PolyCarbonate, polycarbonate)
• Those with physical restrictions on wearing medical devices for clinical trials (for example, when ring-type clinical trial medical devices cannot be applied due to lack of appropriate ring size or other physical defects)
• Those who are judged to have difficulty collecting normal signals when wearing CART-I plus on a finger other than the thumb and forefinger (for example, if there is no CART-I plus model that fits the subject's finger)
• Those who is pregnant
• Those who is currently participating in other clinical trials or who have participated in other clinical trials within 30 days of the screening date
• Other cases where the investigator judges that participation in the clinical trial is inappropriate due to ethical reasons or may affect the results of the clinical trial

The investigators would probably share the results showing the level of agreement between the two measurement methods after deidentification of participant data