Modeling of selective photon capture for collection of fluorescence emitted from dermally-implanted microparticle sensors.

Fluorescence-based sensors have been developed in microsphere formats for many biochemical targets. For these to be deployed in vivo for on-demand monitoring, a matched optical system for delivery of excitation and measurement of emission is needed. To optimize excitation and collection efficiency, statistical ray-tracing may be used to model the distribution of diffusely reflected light resulting from varying input beam profiles. In this work, simulations were performed for models of microsphere fluorescent materials embedded in skin to predict the distribution of excitation and fluorescent photons escaping the skin surface. Simulations prove that the emission photons possess sufficient intensity and spectral information for quantitative analysis. This modeling approach will enable further design of intensity or lifetime instrumentation to maximize signal-to-noise for measurements from implanted sensor particles.