Optimizing probe design for an implantable perfusion and oxygenation sensor

• Published in: Biomedical optics express 2011-08, Vol.2 (8), p.2096
• Main Authors: Akl, Tony J., Long, Ruiqi, McShane, Michael J., Ericson, M. Nance, Wilson, Mark A., Coté, Gerard L.
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; ABSORPTION; APERTURES; BASIC BIOLOGICAL SCIENCES; BLOOD FLOW; BLOOD VESSELS; DESIGN; DYES; HEMOGLOBIN; IMPLANTS; IN VITRO; LIVER; MONITORING; MONTE CARLO METHOD; OPTIMIZATION; OXYGEN; PERFUSED TISSUES; PHANTOMS; POINT SOURCES; PROBES; SENSORS; SIMULATION; VISIBLE RADIATION; WAVELENGTHS
• ISSN: 2156-7085; 2156-7085
• DOI: 10.1364/BOE.2.002096

In an effort to develop an implantable optical perfusion and oxygenation sensor, based on multiwavelength reflectance pulse oximetry, we investigate the effect of source detector separation and other source-detector characteristics to optimize the sensor s signal to background ratio using Monte Carlo (MC) based simulations and in vitro phantom studies. Separations in the range 0.45 to 1.25 mm were found to be optimal in the case of a point source. The numerical aperture (NA) of the source had no effect on the collected signal while the widening of the source spatial profile caused a shift in the optimal source-detector separation. Specifically, for a 4.5 mm flat beam and a 2.4 mm 2.5 mm photodetector, the optimal performance was found to be when the source and detector are adjacent to each other. These modeling results were confirmed by data collected from in vitro experiments on a liver phantom perfused with dye solutions mimicking the absorption properties of hemoglobin for different oxygenation states.