Fig. 2

Challenges in wearable and implantable phototherapy devices. a Wearable phototherapy devices for superficial tissues, emphasizing portability, personalization, and energy supply. b Implantable phototherapy devices for deep tissues, focusing on precise localization, energy supply, and biocompatibility. Challenges of wearable phototherapy devices in clinical applications: c Lack of portability^32,33. d Inadequate personalization to meet individual needs⁵⁷. e Insufficient uniformity of illumination from current light source devices, including traditional light source and LED array^17,19 (reprinted with permission³². Copyright 2021, John Wiley & Sons). f Poor conformity of wearable devices³¹, including issues with joint mobility, sophisticated body surface fit, and lack of comfortability. Challenges of implantable phototherapy devices in clinical settings: g Traditional batteries as power sources raise concerns about implantation and limited functional time^48,58. h Device lifespan is constrained by light output attenuation and rupture⁴³.i Encapsulation may fail due to stretching-induced fractures or erosion from acids or enzymes, leading to leakage. j Biocompatibility is limited by heavy metal toxicity from batteries, in vivo corrosivity, and foreign body reactions²⁵. Figure 2, created with BioRender.com, released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license