A stress analysis method for heart rate data of mHealth devices using poincare plot and complex correlation measures

Mobile health (mHealth) devices, such as smart phones and wristband fitness watches, are capable of measuring heart rate data using the photoplethysmography technology. In recent years, these devices have been used to obtain healthcare information in people's everyday life. However, it is difficult to apply traditional spectral analysis methods for the mHealth heart rate data due to the limited sampling features of mHealth devices. Data of the mHealth devices are recorded with uneven and relatively long sampling intervals, constrained by their hardware issues, i.e., processing speed, memory quantity, etc. This paper attempts to develop a stress analysis method for heart rate data obtained with mHealth devices. The heart rate data are evaluated using Poincare plot. Stress analysis indices, which are based on complex correlation measures of time-varying characteristics in Poincare plots, are examined using stress induction experiments with nine subjects.