Non-contact heart rate and heart rate variability measurements: A review

The following paper investigates published work on non-contact human physiological parameter measurement, more precisely measurement of the human heart rate (HR) and consequently the heart rate variability (HRV), which is considered to be an important marker of autonomic nervous system activity proven to be predictive of the likelihood of future health related events. The ability to perform measurements of cardiac activity in a non-contact manner could prove to become an important alternative to the conventional methods in the clinical field as well as in the more commercially oriented fields. Some of the published work so far indicates that the measurement of cardiac activity in a non-contact manner is indeed possible and in some cases also very precise, however there are several limitations to the methods which need to be taken into account when performing the measurements. The following paper includes a short description of the two conventional methods, electrocardiogram (ECG) and photoplethysmography (PPG), and later on focuses on the novel methods of non-contact measuring of HR with capacitively coupled ECG, Doppler radar, optical vibrocardiography, thermal imaging, RGB camera and HR from speech. Our study represents a comparative review of these methods while emphasising their advantages and disadvantages.