The app is based on contact photoplethysmography (finger is in contact with the built-in camera) which can basically detect changes of the light absorption caused by the pulsation of arterial blood volume.

To make it easier for understanding, the app measures the light reflected in the blood with the phone's built-in camera to complete the detection at any time. When your heart beats, blood flow and light absorption are greater. Between beats, they are less. According to this repeated pattern, this application can measure and analyze the frequency of your heartbeats, and provide you with accurate pulse measurements and results.

If you are interested in photoplethysmography, click to read more at: https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure/all-about-heart-rate-pulse

Photoplethysmography is a very effective method commonly applied in clinical use. It allows you to get quick and accurate information about the performance of your heart throughout the day.

For the best results, please follow these tips:

1. Hold your phone steady and keep it still during measurement.
2. Make sure your fingers are not cold.
3. Gently cover the entire back camera lenses with your fingers.
4. Do not press too hard to avoid affecting the blood flow of your fingers.

If these simple rules are followed, the app guarantees to provide full functionality for the accurate tracking and monitoring of your heart activity.

After measuring your heart rate, the heart rate data are stored locally and display according to the mode and time of your detection.

For the best results, please follow these tips:

1. In different modes, the criteria for evaluating heart rate can be adjusted accordingly. For example, the adult heart rate is 60-100 BPM at normal rest, according to the American Heart Association, and we take it as a reference for the assessment of your heart rate.
2. Based on the heart rate assessment criteria in different modes, we will give you some tips. Due to gender, physical fitness, organ health levels and other factors vary from person to person, the tips we provide are only applicable to most conditions and for reference only. If you choose to adopt them, please consider the risks brought by the corresponding tips on exercise and adjustment methods before starting.

By collating literature information from various places and reconfirming with the doctor, we try our best to provide you with tips for reference, hoping to provide a guarantee for your health.

1. What should you know about your heart rate： https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure/all-about-heart-rate-pulse
2. How does sleep affect your heart rate： https://www.health.harvard.edu/blog/how-does-sleep-affect-your-heart-rate-2021012921846
3. Target Heart Rates Chart： https://www.heart.org/en/healthy-living/fitness/fitness-basics/target-heart-rates
4. Lifestyle Changes for Heart Attack Prevention: https://www.heart.org/en/health-topics/heart-attack/life-after-a-heart-attack/lifestyle-changes-for-heart-attack-prevention
5. Change in Heartbeat: https://www.healthlinkbc.ca/health-topics/aa53422
6. How to Sleep Better: https://www.helpguide.org/articles/sleep/getting-better-sleep.htm
7. Stress Can Increase Your Risk for Heart Disease: https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=1&ContentID=2171
8. How does obesity increase the risk of heart and circulatory diseases: https://www.bhf.org.uk/informationsupport/risk-factors/obesity