Optical instrument design for interrogation of dermally-implanted luminescent microparticle sensors

Luminescence-based sensors have been developed in microparticle formats for biochemical targets such as glucose, enabling use of dermal implants for on-demand monitoring. For these to be deployed and interrogated in vivo, a matched optoelectronic system for delivery of excitation, collection and analysis of luminescence response is needed. In this work, simulations based on Monte Carlo ray-tracing were performed for models of luminescent microparticle materials embedded in skin. The spectral and spatial distribution of luminescence escaping the skin was determined for different concentrations, implantation depths, and input beam sizes. Results indicate that the implant environment does not significantly alter the measured spectral intensity ratios. The escaping emission light possesses measurable power and spectral information for quantitative analysis. Using these findings, an optical system has been designed specifically for sensor interrogation and response acquisition, and is currently implemented in hardware. Following benchtop validation and signal-to-noise maximization with tissue phantoms, the instrument will be used for measurement on sensors in rat subjects.