Optical design of a tunable microneedle array for photodynamic therapy of metastatic melanomas

Abstract

The need for photodynamic therapy is increasing with the rise of skin cancer melanoma detection. However, low penetration depth of light in the UV range and higher scattering of skin tissues cause harsh clinical practices and reduced irradiance for the activation of chemicals such as photosensitizers to facilitate cell necrosis of malignant tumors. In this paper, a tunable microlens integrated on a microneedle array is designed for variable focusing to reduce melanomas at multiple sites with an improved intensity for reactive oxygen species production. A light distribution of 36% percent of the input intensity is achieved at the targeted distance of 4.35 mm for blue light. Red light attained a light distribution of 13% of the input intensity at a targeted distance of 6.5 mm. Designing such a light, delivery-based in-vivo biomedical device is of extreme importance for photodynamic therapy of skin cancer on and beyond the epidermal tissue layer.