Jessica Magallanes Castaneda MSc Dissertation 2015/16

Capturing your heart rate using a smartphone

Supervised by M.Villa-Uriol

Abstract

Heart Rate (HR) and Heart Rate Variability (HRV) are important indicators of general health. Electrocardiogram is the traditional technique to obtain these parameters; however, more portable methods have evolved. Current Mobile Applications that calculate HR, use Photoplethysmography (PPG) method; PPG signal is obtained while the fingertip is placed on the back camera of the smartphone . In spite of the existence of mobile applications that measure HR without the need of any other device, the applications that calculate HRV require an external monitor to do the measurement. It has been proved that HRV can be derived from PPG signal with a sampling rate higher than 100Hz; nevertheless, the smartphone  camera provides up to 30Hz. The objectives of the present project are: firstly, to build a mobile application to monitor HR and HRV accurately, and second, to evaluate the accuracy of the application with healthy individuals. The application that was developed on this project was evaluated against a commercial chest strap monitor. The application was able to obtain HRV index with an average error of 11.8%, a minimum error of -1 and a maximum error of -16.94 points; however, half of the evaluation results for HRV are less than 5 points far from the actual HRV index. On the other hand, Resting Heart Rate was obtained with an average error of 1.47%, a minimum error of 0 beats and a maximum of -3 beats. The mobile application got a smaller average error than the studied algorithms for obtaining resting heart rate.