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Journal of Biomedical Optics

Three-dimensional printed miniaturized spectral system for collagen fluorescence lifetime measurements
Author(s): Luwei Zou; Ronald J. Koslakiewicz; Mohamad Mahmoud; Mehdi Fahs; Rui Liu; Joe Fijiou Lo
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Paper Abstract

Various types of collagens, e.g., type I and III, represent the main load-bearing components in biological tissues. Their composition changes during processes such as wound healing and fibrosis. When excited by ultraviolet light, collagens exhibit autofluorescence distinguishable by their unique fluorescent lifetimes across a range of emission wavelengths. Here, we designed a miniaturized spectral-lifetime detection system as a noninvasive probe for monitoring tissue collagen compositions. A sine-modulated LED illumination was applied to enable frequency domain fluorescence lifetime measurements under three wavelength bands, separated via a series of longpass dichroics at 387, 409, and 435 nm. We employed a lithography-based three-dimensional (3-D) printer with <50  μm resolution to create a custom designed optomechanics in a handheld form factor. We examined the characteristics of the optomechanics with finite element modeling to simulate the effect of thermal (from LED) and mechanical (from handling) strain on the optical system. The geometry was further optimized with ray tracing to form the final 3-D printed structure. Using this device, the phase shift and demodulation of collagen types were measured, where the separate spectral bands enhanced the differentiation of their lifetimes. This system represents a low cost, handheld probe for clinical tissue monitoring applications.

Paper Details

Date Published: 1 July 2016
PDF: 10 pages
J. Biomed. Opt. 21(7) 075001 doi: 10.1117/1.JBO.21.7.075001
Published in: Journal of Biomedical Optics Volume 21, Issue 7
Show Author Affiliations
Luwei Zou, Univ. of Michigan-Dearborn (United States)
Ronald J. Koslakiewicz, Univ. of Michigan-Dearborn (United States)
Mohamad Mahmoud, Univ. of Michigan-Dearborn (United States)
Mehdi Fahs, Univ. of Michigan-Dearborn (United States)
Rui Liu, Univ. of Michigan-Dearborn (United States)
Joe Fijiou Lo, Univ. of Michigan-Dearborn (United States)

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