Bright idea


It was a lightbulb moment for Associate Professor Wei Shen of
the Engineering Faculty - an instant that saw a simple observation of
a burning candle stick spark into scientific discovery.

Associate Professor Wei Shen

"I was staring at the candle stick and thinking how the wick carries the wax fluid along the thread fibres. The idea of using thread to guide fluid wicking then grabbed me," Associate Professor Shen said.

In a world first, a team led by the chemical engineer used ordinary cotton thread and sewing needles to literally stitch together a stampsized microfluidic analytical device - transforming the humble material into a potentially life-saving instrument capable of detecting diseases such as kidney failure and diabetes.

"The concept was born from that initial idea, that it would be much easier to use thread to transport fluid than to make microfluidic tunnels through a solid material, which is how these devices are usually made," Associate Professor Shen said.

"Thread transports liquid through capillary gaps between fibres, so there is no need for an external pump to pump the fluid. And because it is white, thread can display colour changes. So it was an ideal, inexpensive material for making lab-on-chip diagnostic devices."

Microfluidic analytical devices, which have been produced from a range of materials over the last couple of decades, allow scientists to carry out chemical analyses of minute fluid samples, such as blood
and urine.

They have generally been produced by carving
channels into chips made of silicon, glass, ceramic or metal, or through a complicated and expensive
photolithographic process.

The cotton-based device works by wicking fluid along
the microscopic fibres of cotton thread sewn into a
polymer film.

The thread's absorbent property ensures a defined flow for fluids, so complex channels and barriers do not need to be etched into the chip. The hope is that the cotton-based lab-on-chip concept will lead to the provision of low-cost disease screening in
developing countries.

"There are emerging technologies in the area of paper-based microfluidic diagnostic devices, however the disadvantage is that it requires expensive equipment to fabricate the sensors.

The benefit of cotton thread-based devices is that they can be made using simpler equipment, such as sewing machines, so they could be produced in developing regions. We are in the very early days of this research, but we are very excited about where it could lead.

"Communities in the developing world are vulnerable to disease, so early detection and screening systems can save many lives.

However, many of the current commercial devices are not cheap enough for large-scale health-care projects involving disease detection, so an affordable alternative could make a huge difference," he said. Associate Professor Shen has been invited to present his thread research at the fourth annual Annual Enabling
Point-of-Care Diagnostics Conference, being held in Washington DC, later this year, and will showcase his innovation to representatives from the Bill and Melinda Gates Foundation.


"Communities in the developing world are vulnerable to disease, so early detection and screening systems can save many lives."

Associate Professor Wei Shen of the
Engineering Faculty