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Spotlight on Optics

Spotlight on Optics


  • July 2012

Optics InfoBase > Spotlight on Optics > Microfluidics based phantoms of superficial vascular network

Microfluidics based phantoms of superficial vascular network

Published in Biomedical Optics Express, Vol. 3 Issue 6, pp.1350-1364 (2012)
by Long Luu, Patrick A. Roman, Scott A. Mathews, and Jessica C. Ramella-Roman

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Spotlight summary: Quantitative assessment of blood flow continues to be of considerable interest in biomedical research. A number of diseases, including cancer and diabetes, have been linked to changes in blood flow and in blood oxygenation. A range of optical techniques have been developed to measure blood flow, including: laser Doppler, Doppler optical coherence tomography and Doppler photo-acoustic tomography. As these techniques begin to reach the clinical stage and in order to optimize their performance, it is necessary to develop accurate, reliable and readily reproducible phantoms, which can be used to calibrate and validate techniques. These phantoms also have the potential to be used as imaging standards: a requirement of regulatory bodies. Despite this growing need, the majority of flow phantoms proposed to date employ overly simplistic geometries and have optical properties that are not relevant for tissue. Another important issue is that each laboratory has developed their unique “recipe” that is often not easily reproduced by other researchers in the field. These factors impede the development of flow imaging techniques.

The authors have proposed a technique that implements a flow phantom in microfluidics, to significantly advance the development of flow phantoms. The flexible technique proposed by the authors can form micro-channels smaller than 20 um. The authors formed these channels in widely available inexpensive materials such as epoxies, plastics and household tapes. The experimental setup allows for rapid prototyping. Importantly, it should be possible to replicate this setup in other laboratories, allowing researchers to take advantage of this development directly. The paper presents an impressively thorough study of the microfluidics methods. The authors characterized the micro channels using scanning electron microscopy and investigated the theoretical flow dynamics within the channels using finite element analysis. Then, the authors tested their phantoms using a commercial speckle-based flow imaging system.

The most important development in this work is the capability to fabricate flow phantoms with complex geometries. The authors demonstrated phantoms with multiple channels, both overlapping and overlaying. They also demonstrated the use of a retinal image captured using a fundus camera as a template for the fabrication of a microfluidic phantom.

In conclusion, the developments reported in this paper will allow researchers to readily and reliably produce phantoms with relevant geometries matching that of real vasculature. These phantoms can be produced rapidly and inexpensively. This work represents the first significant attempt to incorporate knowledge of the geometry of vasculature into the design of a flow phantom.

--Brendan Kennedy

ToC Category: Calibration, Validation and Phantom Studies
OCIS Codes: (120.3890) Instrumentation, measurement, and metrology : Medical optics instrumentation
(170.3880) Medical optics and biotechnology : Medical and biological imaging

Posted on July 03, 2012

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