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Breakthrough technique separates, detects irregular bioparticles

5 Aug 2013

(From right) Assoc Prof Zhang, Research Fellow Shashi Ranjan and PhD student Kerwin Kwek Zeming with their invention

The I-shape microfluidic chip is only slightly bigger than a S$1 coin
NUS scientists have developed a microfluidic device – precision equipment that controls and manipulates fluids in sub-millimetre scale – that promises more effective rapid diagnostics and treatment in diseases. Published in Nature Communications, the invention’s ability to isolate non-spherical and irregular bioparticles – such as bacteria and red blood cells – is a major breakthrough as current systems can only handle spherical particles.

Led by Associate Professor Zhang Yong from the Department of Bioengineering, the team is focusing on the rapid separation and detection of bacteria from pathological samples. The new device can potentially be deployed for fast diagnostics of bacterial infections, to replace the traditional detection technique based on bacterial culture.

Assoc Prof Zhang explained that the 100-year-old existing approach is still being used as no new alternative is available for effective separation of bacteria from pathological samples such as blood. His team’s method can complete the diagnosis process in less than an hour compared to 24 to 48 hours required for bacterial detection by using conventional methods.

One of the biggest challenges was creating a device capable of detecting the smallest dimension of bioparticles while still giving good throughput. The engineers hit upon the idea of inducing rotation or flipping of non-spherical particles to take in its longest dimension into account. Then, they conducted computational modelling to study the flow profiles of fluid through different designs.

The result – a unique I-shape pillar system that allows rotation and efficient separation of non-spherical particles. This has shown 100 per cent separation of red blood cells from blood samples, outperforming conventional cylindrical pillar arrays that produced almost no separation. The team also tested their device on particles of diverse shapes and sizes, including rod-shaped bacteria.

The researchers have successfully filed a US provisional patent for their world’s first technique. Besides the promise of replacing existing old techniques, the invention can be applied in areas such as the detection of bacteria in water and food for environmental engineering, as well as food safety control. As the separation and detection of bioparticles are carried out in microfluidic channels, many channels can be fabricated on the same chip to process different types of bioparticles simultaneously.

The team is collaborating with clinicians from the National University Health System to get input on real medical problems and to test clinical samples to validate the device. Once completed, they plan to commercialise the product.