Monte Carlo modeling for implantable fluorescent analyte sensors

• Published in: IEEE transactions on biomedical engineering Vol. 47; no. 5; pp. 624 - 632
• Main Authors: McShane, M.J., Rastegar, S., Pishko, M., Cote, G.L.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.05.2000; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Biological and medical sciences; Biomedical optical imaging; Biosensors; Computer Simulation; Fluorescence; Fluorescent Dyes - pharmacokinetics; Humans; Implants (surgical); Light propagation; Mathematical models; Medical sciences; Miscellaneous; Models, Biological; Monitoring; Monte Carlo Method; Monte Carlo methods; Monte Carlo simulation; Optical design; Optical propagation; Optical properties; Optical sensors; Optoelectronic and photonic sensors; Photons; Probes; Sensors; Skin; Skin - chemistry; Spectrometry, Fluorescence - instrumentation; Spectroscopy; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Tissue; Implanted material; Monte Carlo method; Tissue; Sensitivity analysis; Propagation; Simulation; Surgery; Optical properties; Optical sensor; Modeling; Photon; Fluorescence spectrometry
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/10.841334

A Monte Carlo simulation of photon propagation through human skin and interaction with a subcutaneous fluorescent sensing layer is presented. The algorithm will facilitate design of an optical probe for an implantable fluorescent sensor, which holds potential for monitoring many parameters of biomedical interest. Results are analyzed with respect to output light intensity as a function of radial distance from source, angle of exit for escaping photons, and sensor fluorescence (SF) relative to tissue autofluorescence (AF). A sensitivity study was performed to elucidate the effects on the output due to changes in optical properties, thickness of tissue layers, thickness of the sensor layer, and both tissue and sensor quantum yields. The optical properties as well as the thickness of the stratum corneum, epidermis, (tissue layers through which photons must pass to reach the sensor) and the papillary dermis (tissue distal to sensor) are highly influential. The spatial emission profile of the SF is broad compared that of the tissue fluorescence and the ratio of sensor to tissue fluorescence increases with distance from the source. The angular distribution of escaping photons is more concentrated around the normal for SF than for tissue AF. The information gained from these simulations will he helpful in designing appropriate optics for collection of the signal of interest.