Wearable cuffless blood pressure monitoring: From flexible electronics to machine learning

Hypertension significantly contributes to the widespread occurrence of cardiovascular disease globally. Routine portable blood pressure monitoring is crucial for the prevention and screening of hypertension. Nevertheless, the bulky nature of cuff sphygmomanometers commonly used in clinical settings causes discomfort for patients. Wearable cuffless blood pressure monitoring has received significant attention as a result. Advances in flexible electronics and machine learning have provided new impetus to the development of wearable cuffless blood pressure monitoring, offering potential solutions to these challenges. Here, we review the theoretical foundations, sensors and back-end signal processing for wearable cuffless blood pressure monitoring from a full-process perspective, particularly emphasizes the new developments introduced by flexible electronics and machine learning. Flexible mechanical sensors, optical sensors, ultrasonic sensors, and flexible electrodes efficiently capture signals related to blood pressure, while the signal processing enabled by machine learning accurately analyzes the raw signals into blood pressure waveforms. Finally, the future challenges and opportunities of wearable cuffless blood pressure monitoring are envisioned.