Fig. 1. Diverse potential applications of wireless optical techniques in healthcare domain^[8]

Fig. 2. Typical wearable wireless optical healthcare monitoring device^[10]

Fig. 3. Illustration of scenes with active wireless optical link^[16]

Fig. 4. Human body models in wireless optical body area link. (a) Two-dimensional basic model (8 faces); (b) three-dimensional full model (1796 faces)^[16]

Fig. 5. RFID and wireless optical passive link transmission scheme. (a) Hybrid RFID-OWC system model; (b) position relationship of tag and reader^[19]

Fig. 6. Hybrid passive-active wireless optical health monitoring system architecture^[17]

Fig. 7. Applications of wireless optical relay link in RF sensitive environment^[23]

Fig. 8. Healthcare wireless optical communication system based on amplification and forward relay link^[21-23]

Fig. 9. Medical VLC system^[36]. (a) Architecture of indoor VLC system in a hospital environment using LED devices; (b) ECG signal received via VLC medical information system

Fig. 10. System architecture of mobile health–monitoring system using VLC transmission^[27]

Fig. 11. Wearable EEG transmission experiment^[24]. (a) Wearable EEG measurement setup (side view); (b) front view with different electrode placement

Fig. 12. Prototype of receiver module. (a) Receiver container designed using three-dimensional printer; (b) components of module; (c) average voltage tracking circuit for each color channel^[30]

Fig. 13. IMD has an embedded light sensor and smartphone flashlight acts as a light source^[1]