The aim of this paper is to review recent developments and commercialized products in the field of wearable wellness sensors and devices (WWSD). Although there are several dedicated researches, the completed theories and systematic techniques have not been well established. Therefore, we divided the WWSD into four different topics (healthcare, safety & prevention, gaming & lifestyle, and sports & fitness), and review the state of the arts and challenges on the applications on the sensor and device technologies with particular focus on WWSD. We also review the limitations of the current technologies on the developments and commercialized products. Finally, we suggest and discuss new research topics related on the four topics of the WWSD.
