NTU scientist catches world's attention with laser technology invention

A scientist from Nanyang Technological University (NTU) has invented an innovative device that can identify and detect contaminants in treated water, such as water-borne bacteria, in just one hour, down from the current two days.

The breakthrough laser technology, used in the device, has been published in the world-famous scientific magazine Nature Communications, a publication known for highlighting global innovations and important groundbreaking research.

Prof Liu Ai Qun from NTU’s School of Electrical & Electronic Engineering has invented a laser-technology device that manipulates light to detect bacteria in water which eliminates the cumbersome process of testing water in the lab for two days. Now, the bacteria can be detected in just one hour, a boon for countries when fighting water-borne diseases.

The 51-year-old father of one is no stranger to innovation as he had previously won many awards: the University Scholar Award from NTU; the Institute of Engineers Singapore award; as well as leading an NTU doctoral team to win the regional Young Inventors Awards by developing a user-friendly kit to detect cancer in its earliest stage.

His latest brainchild, the “Parasitometer”, is a stand-alone device using a breakthrough laser technology that has a high detection rate. It can pick out a single bacteria cell out of a ten-litre drinking water sample. It will also reduce the costs of such water tests by about eight times as there is no need for chemical reagents and lab facilities manned by trained personnel.

To market and further develop the “Parasitometer” into a commercial product, NTU will be spinning off a start-up company, named Water Optics Technology. It will be jointly owned by Prof Liu and NTU.

Prof Liu’s technology works by directing water to flow through a tiny channel (about the width of a human hair) within a small chip and shining a laser through the treated water. Any microscopic contaminants such as bacteria or particulate matter can be detected from the way laser light bounces off and through it.

A small camera sensor is then used to capture the data of the light refraction, which will then identify the contaminants.

Prof Liu said that among the various bacteria targeted for detection are Cryptosporidium and Giardia. These pathogens if present in drinking water can cause diarrhoea in humans.

“Using our new technology, we are able to identify cells by knowing their cell shape, the diameter and size, and their refractive index - how well they reflect light and let light through,” said Prof Liu.

“We will be able to know what sorts of contaminants are found in the water sample, with up to 90 per cent accuracy, and this will definitely help water agencies worldwide when they need to perform tests and diagnostics of their water supply.”

The project, which took three years, is funded by the Environment & Water Industry Programme Office (EWI) and supported by the Singapore National Research Foundation under its Environmental & Water Technologies Strategic Research Programme. EWI was set up in 2006 to spearhead the growth of Singapore’s water industry. Through funding of promising research projects, the EWI aims to foster leading-edge technologies and create a thriving and vibrant research community in Singapore.

Mr Chew Men Leong, Chief Executive of PUB, the national water agency and Executive Director of EWI said: “Singapore’s investments in R&D over the last 40 years have strengthened its position as a hub for water technologies.”

“Today, we have a thriving cluster of more than 70 local and international water companies and a vibrant water research eco-system with 24 research centres undertaking projects in various domains like membrane, biomimicry and low energy seawater desalination.

“Together with the local research community, more than 340 R&D projects have been carried out so far. We welcome individuals and organisations to step forward with more of such exciting R&D ideas that will benefit the global water industry.”

While the current prototype device weighs 50 kilograms and measures 60cm x 50cm x 50cm, Prof Liu estimates that the actual device will be half the size and half the weight of the current prototype by the time it hits the market, costing an estimated $15,000.

This is also the first time that a scientist has demonstrated how to manipulate and bend light in liquid, through the use of microfluidics.

A fellow expert in optics and microfluidics, Assoc Prof Claus-Dieter Ohl, from NTU’s School of Physical and Mathematical Sciences said Prof Liu’s technology has strong potential for novel applications in other fields.

"Transformation optics - how light is bent using lenses - is a paradigm shift which allows for the construction of novel optical instruments, leading to new technology that can enable cloaking of large physical objects,” said Prof Ohl.

“Using this paradigm shift, Prof Liu replaced the lens component with fluids, which allows light to be manipulated at will depending on how the fluids are transported and mixed - allowing for complex optical beam shaping. Not only are these exciting results a test-bed for Transformational Optics but it can also be used for the critical applications in life sciences."

The discovery opens up new cutting-edge research fields between photonics/optics and microfluidics, and could possibly be used to spark other innovations in the areas of instrumentation, signal processing and biomedical systems. For example, a new generation of products, such as droplets 3D display, on-chip microscope and camera are now possible.

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