Wearable medical devices mainly use built-in or installed software to capture physiological signals and then feed them back to the wearer. The wearer can quickly know their current physical health condition in real time and make timely adjustments. Along with the development of smart phones, wearable devices such as health bracelets and watches are becoming more and more popular. They can be easily purchased in physical stores or through online shopping. They are adding more and more functions, including dynamic heart rate monitoring, calculation of calories, blood pressure measurement, step management, motion tracking, sedentary reminders, and sleep management, etc. With these health management functions becoming more and more diverse, it has raised the question, what is the difference between the physiological data monitored by a bracelet, as compared to that collected using a hospital's precision instruments?