The purpose of this study is to collect data to develop and evaluate the use of state-of-the-art machine learning approaches within a mobile phone application for the estimation of blood pressure.

Participants will simultaneously acquire blood pressure measurements through a cuff-based, automatic, over-the-counter blood pressure monitor on the upper arm, while recording an optical signal through the camera of a smartphone on the tip of the index of the opposite arm.

Inclusion Criteria:

1. Be at least 18 years old (at least 19 years old in Alabama and Nebraska, at least 21 years old in Puerto Rico);
2. Live in the United States of America
3. Have an Android smartphone
4. Have access to an arm-worn blood pressure monitor (cuff)
5. Have access to the Google Play store to download the OptiBP study app on their phone
6. Be comfortable communicating in written and spoken English
7. Be willing and able to provide informed consent to participate in the study

Exclusion Criteria:

1. Known contact dermatitis to nickel/chromium
2. Lesion or deficiency on hand, preventing placing a finger on the smartphone camera
3. Known dysrhythmia like bigeminy, trigeminy, isolated VPB, atrial fibrillation

The data is anonymized and used for machine learning training