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The mosquito’s bite and other stories

In a seminal paper that he wrote five years ago with a Japanese collaborator, Suman Chakraborty, a professor of mechanical engineer at the Indian Institute of Technology (IIT), Kharagpur, described how various muscles relax and tense, eventually pumping the blood into the female mosquito’s mouth. Premium
In a seminal paper that he wrote five years ago with a Japanese collaborator, Suman Chakraborty, a professor of mechanical engineer at the Indian Institute of Technology (IIT), Kharagpur, described how various muscles relax and tense, eventually pumping the blood into the female mosquito’s mouth.

An engineer probing the hidden life of liquids learns how mimicking an insect's blood lust can change our approach to disease diagnostics

To be vexed by the female mosquito—one of humanity’s greatest and oldest scourges—is easy. To learn from it is not quite as easy, but one Indian mechanical engineer has painstakingly found that the organ it uses to spread disease and death can inspire new ways to prolong life.

That tool is the labium, a sheath that encases the mosquito’s snout, which hammers its way through the skin when it bites, with the ability to bend at right angles in its search for a blood vessel. The labium is a complex biological machine, composed of parts that bite and grip and tubes that send saliva in and suck blood out.

In a seminal paper that he wrote five years ago with a Japanese collaborator, Suman Chakraborty, a professor of mechanical engineer at the Indian Institute of Technology (IIT), Kharagpur, described how various muscles relax and tense, eventually pumping the blood into the female mosquito’s mouth. Inspired by the intricate process behind a seemingly simple bite, Chakraborty, 40, and Kazuyoshi Tsuchiya, his colleague from Tokai University, evolved a painless “micro-needle" that could extract blood and inject drugs more efficiently than before for a variety of medical applications.

“We tried to take the lesson that (a) female mosquito’s blood sampling is essentially triggered by creating a suction pressure," says Chakraborty, one of the winners of the Bhatnagar Award, India’s national prize for scientists under 45. Round-faced, bespectacled and an avid fan of the great cricketer Sachin Tendulkar, Chakraborty’s work is concerned with the relatively new field of microfluidics, the interdisciplinary science of fluid flows at a micro scale, sometimes visible to the eye, sometimes not.

Straddling biology, physics, chemistry and engineering, microfluidics is less than 40 years old. It encompasses the rush of ink in computer printers, the flow of blood to test blood-sugar levels in diabetes mellitus patients, the micro-needle’s prime target. Many diabetes patients must draw blood and inject insulin many times a day, often undergoing pain and trauma.

Only marginally thicker than a mosquito’s labium and two times finer than a human hair, the micro-needle—made of titanium, a light, strong metal—allows diabetes patients to draw only a drop of blood instead of a syringe-full. Obviously, there are commercial applications. “After we did the scientific work, I was approached by a few multinational companies (based in India)," says Chakraborty, author of more than 200 scientific papers. “Unfortunately, there were many bottlenecks, especially considering that our Japanese counterparts are also involved."

In keeping with India’s poor record on transferring laboratory work to the real world, the technology was never transferred, although it is available. This is particularly unfortunate because a device like the micro-needle could potentially be inexpensive and efficient, ideal for poor countries like India.

Another promising development from the microfluidics work of Chakraborty’s team is the creation of a laboratory on a compact disc, similar to the music CDs that now face obsolescence.

Here, too, the motivation was the same: a quick, inexpensive and portable test for important diseases using tiny amounts of blood, urine or other liquids. Instead of time-consuming multiple laboratory tests or manufacturing a sophisticated microfluidics-based device, a whirling CD with grooves about the thickness of a human hair can simplify testing. The miniaturized laboratory on a single CD can mix fluids, separate them, hasten testing and is easy to manufacture.

The CD-based device holds particular promise for diagnostics based on nucleic acids, which means finding traces of the genetic blueprint of pathogens, DNA or RNA—and, so, confirmation of an infection—in a drop of human blood. But identifying the nucleic acids of such bugs currently requires expensive laboratories and specialized staff. Compacting the entire process onto a CD holds revolutionary potential.

“Traditional microfluidic device-fabrication requires a clean room, as in the semiconductor industry," explains Chakraborty, whose collaborator for the project is the University of California (UC) at Irvine in the US. CD fabrication requires a simple bench-top machine. The collaboration has worked well because Chakraborty is strong on theory and the UC-Irvine group strong on experimentation. The Indian professor’s group, though, is trying to walk their talk.

“Suman has built a nice lab in a short amount of time and was able to attract some very bright students (who) are now actually setting up a company around the lab-on-CD in India," says Marc Madou, a professor of mechanical, aerospace and biomedical engineering at UC Irvine. “I was most happy when Suman and his group very quickly came up with new ideas around the Lab-on-CD."

As the micro-needle and the lab-on-a-CD indicate, microfluidics has vast healthcare applications. Chakraborty began his foray into microfluidics about eight years ago, a time when there was no established Indian group working in the field. He’s come a long way since. “Suman is undaunted by any challenge to delve into something totally new to him," says Madou.

Underlying these challenges is a strong understanding of the physics involved. Chakraborty’s group at IIT-Kharagpur first demonstrated how rough surfaces could actually allow liquids to flow quicker than over smooth surfaces. They achieved this seemingly impossible task by showing how specially designed rough surfaces made with hydrophobic—or water repelling—materials can trigger the formation of bubbles in narrow channels, a smoothening layer that water can speedily slip over. “I call it, ‘the rough makes it smooth’," says Chakraborty. The “spontaneous formation" of a mild electric charge spurs the smoothness.

The result: a high rate of pumping liquid—without using a pump.

Similarily, in developing the lab-on-a-CD, Chakraborty described how droplets form on a spinning platform—according to Madou, his Indian partner was one of the first to do so in a research area gaining momentum globally.

As manipulation and control of tiny amounts of liquid becomes easier for science, Chakraborty hopes to realise the potential of microfluidics in greater measure. “Quite often in research we undertake studies for scientific glory…we take up practical problems more relevant to the developed world," he says. “This is where I want to make an impact. Not that I have been by and large successful until now, but my efforts will go on."

Samar Halarnkar is a Bangalore-based journalist. This is a fortnightly column that explores the cutting edge of science and technology. Comments are welcome at frontiermail@livemint.com. To read Samar Halarnkar’s previous columns, go to www.livemint.com/frontiermail-

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