Review of Flexible Biomedical Sensors: Design, Application, and Challenge

With a growing population and the subsequent rise of age-associated diseases, the development of soft materials and sensors in the field of medical care has great potential to prolong life expectancy and enrich the quality of life for the next generation. From an overall perspective, wearable flexible sensors not only have excellent mechanical properties that are compatible with irregular surfaces but also are biocompatible and eco-friendly. They are more portable and convenient compared with bulky rigid materials-based sensors. With the emergence of novel materials, the flexible sensors that used piezoelectric materials are usually self-powered, thus not requiring a complicated external powering approach. Moreover, the wearable flexible sensors exhibit significant potential in detecting biophysical signs, such as pulse rate, body movement status, body temperature, and heart rate, and analyzing glucose, lactate, pH, and other human health indicators. This article summarizes different types, designs, structures, and specific applications of wearable flexible sensors, and the correlated working principles are also presented. Finally, it concludes with a summary of the challenges associated with the sensors in medical care and an outlook on the future directions.