Functional microscopic imaging of in vivo tissues aims at characterizing parameters at the level of the unitary cellular components under normal conditions, in the presence of blood flow, to understand and monitor phenomena that lead to maintaining homeostatic balance. Of principal interest are the setting of shear stress on the endothelium; formation of the plasma layer, where the balance between nitric oxide production and scavenging is established; and formation of the oxygen gradients that determine the distribution of oxygen from blood into the tissue. Optical techniques that enable the analysis of functional microvascular processes are the measurement of blood vessel dimensions by image shearing, the photometric analysis of the extent of the plasma layer, the dual-slit methodology for measuring blood flow velocity, and the direct measurement of oxygen concentration in blood and tissue. Each of these technologies includes the development of paired, related mathematical approaches that enable characterizing the transport properties of the blood tissue system. While the technology has been successful in analyzing the living tissue in experimental conditions, deployment to clinical settings remains an elusive goal, due to the difficulty of obtaining optical access to the depth of the tissue.
A new non-invasive real-time system for the monitoring and control of microfluidodynamic phenomena is proposed. The
general purpose design of such system is suitable for in vitro and in vivo experimental setup and therefore for
microfluidic application in the biomedical field such as lab-on-chip and for research studies in the field of
microcirculation. The system consists of an ad hoc optical setup for image magnification providing images suitable for
image acquisition and processing. The optic system was designed and developed using discrete opto-mechanic
components mounted on a breadboard in order to provide an optic path accessible at any point where the information
needs to be acquired. The optic sensing, acquisition, and processing were performed using an integrated vision system
based on the Cellular Nonlinear Networks (CNNs) analogic technology called Focal Plane Processor (FPP, Eye-RIS,
Anafocus) and inserted in the optic path. Ad hoc algorithms were implemented for the real-time analysis and extraction
of fluido-dynamic parameters in micro-channels. They were tested on images recorded during in vivo microcirculation
experiments on hamsters and then they were applied on images optically acquired and processed in real-time during in
vitro experiments on a continuous microfluidic device (serpentine mixer, ThinXXS) with a two-phase fluid.
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