| dc.description.abstract | Phototherapy is the use of light ranging from ultraviolet to near-infrared wavelengths for clinical applications such as treatment of acne, wound healing, and inactivation of bacteria and fungi. The application is dependent on the wavelengths used and required penetration depth due to the nature of light-tissue interactions. Light emitting diodes (LEDs) assembled into arrays have become a popular light source in phototherapy because of their high efficiency and lower costs replacing expensive lasers and bulky, inefficient filtered lamps. However, when illuminating close to the skin for therapeutic applications, LEDs form concentrated areas of light causing uneven illumination on the treatment area that has been shown to reduce the efficacy of phototherapy.
In this work, an optical model of a previously fabricated flexible LED array used in blue light therapy was created and validated. To create a more uniform light distribution for use on the skin, a diffuser layer composed of silicone and hollow glass microspheres was added between the LED array and the skin surface in the model. This layer was optimized to maximize uniformity while minimizing irradiance loss. Flexible diffusers were fabricated to validate the model with the LED array source. A 1-2 mm thick diffuser layer with hollow glass microsphere volume fraction of 5-10% was determined to provide sufficient diffusion while maintaining an average irradiance >45 mW/cm2, the minimum irradiance required for blue light inactivation of bacteria. This work is translatable to other phototherapy applications requiring uniform light irradiance from a light source placed near or on the skin. | en |
