Abstract:
Microfluidic flows are an increasing area of interest used for “lab-on-a-chip” bioanalytical
techniques, drug discovery, and chemical processing. This requires optical,
non-invasive flow-visualization techniques for characterising microfluidic flows. Optical
Coherence Tomography (OCT) systems can provide three-dimensional imaging
through reasonably-opaque materials with micrometre resolution, coupled to a single
optical axis point using optical fibre cables. Developed for imaging the human eye,
OCT has been used for the detection of skin cancers and endoscopically in the human
body. Industrial applications are growing in popularity including for the monitoring
of bond-curing in aerospace, for production-line non-destructive-testing, and for
medical device manufacturing and drug encapsulation monitoring.
A dual beam Optical Coherence Tomography system has been developed capable
of simultaneously imaging microfluidic channel structures, and tracking particles
seeded into the flow to measure high velocity flows, using only a single optical access
point. This is achieved via a dual optical fibre bundle for light delivery to the sample
and a custom high-speed dual channel OCT instrument using an akinetic sweep
wavelength laser. The system has 10 μm resolution in air and a sweeping rate of
96 kHz. This OCT system was used to monitor microfluidic flows in 800 μm deep
test chips and Poiseuille flows were observed.
