Systems and methods of polymerizing compositions with a light source may be provided. A device may include a handheld light source, which may include an LED, which may provide light at limited wavelengths to polymerize a composition. The device may be used to photo-polymerize dermal fillers transdermally via ex vivo applications. Dermal fillers may be compositions including PEODA 3400 and eosin Y, which may be polymerizable when exposed to light.