Nowadays physiological monitoring systems are becoming completely wearable devices, in healthcare, which are smart and power efficient devices for healthcare remote monitoring, diagnosis and prevention. The design and development of a new generation of sustainable and low-cost medical wearable devices present several challenges that need to be addressed from a global perspective. The ultimate intention of this PhD is to propose a novel solution for specific needs of medical wearables and exploit the characteristics of bio-signals to develop energy-efficient strategies using AI. PPG is an attractive bio-signal, especially for wearable applications used for PPG signal data collection and analysis.