“…Existing works on driver vital sign monitoring include the sensor-based methods [153]- [158], vision-based methods [262]- [265] and radio frequency (RF)-based methods [266]- [278]. The sensor-based methods require wearable sensors such as photoplethysmography (PPG) [156], ECG [154], [155], EEG [153], [279], voltage-controlled oscillators [157], and electromagnetic coupled sensor [158] to capture physiological signals for vital sign analysis. They are accurate due to the direct contact with a human body but tend to be cumbersome, uncomfortable, and distracting for a driver when driving, thus hindering practical applications.…”