SILK IS THE SECRET TO THESE CHEAP, ACCURATE DIAGNOSTIC TESTS

COURTESY OF ACHIRA LABS

MOST DIP-AND-GO DIAGNOSTIC STRIPS—COMMON drugstore tests for pregnancy, or blood glucose—are made of paper or plastic. Cheap and easy to manufacture, those are the go-to substrates for these types of tools, affordable and disposable. But at Achira Labs, a biotech startup in Bangalore, researchers are spinning up their diagnostic sensors from silk.

The same stuff as scarves and saris going into sensors? It’s not as lavish as it sounds. Not only does the material work better than plastic—threads can more easily direct the flow of fluids—it’s also a far thriftier option in a country rich in textiles: Silk strips cost about one-third the price of commercial testing kits, which might go for $10 a pack.

Dhananjaya Dendukuri, Achira’s founder and CEO, has been pioneering this kind of tech, called microfluidics, since his days as a PhD at MIT. He co-invented a now-popular technology called “flow lithography,” which uses tiny hydrogel particles—the bendy, absorbent stuff contact lenses are made of—as sensing elements. When he graduated in 2007, Denduruki joined forces with a drug discovery company in Bangalore, applying his microfluidics ideas to some of their problems.

But he quickly found there was a better application for his innovations. “I realized that affordable diagnostics is a big, unmet need, and a clearly definable problem,” says Denduruki, “unlike the obscure ones that researchers tackle in labs, which would only be of interest to a hundred people at best.” That was especially true in India, where access to affordable, quality healthcare is tough to come by, and laboratories are rare. Doctors and patients have to rely on quick, low-cost methods to detect and monitor disease—like the simple test strips that can identify everything from blood glucose for diabetics to rotavirus infections.

Denduruki’s technology, he realized, could make those types of tests much more powerful—and accessible. The tiny beads were perfect little starting blocks for diagnostic sensors, since they were highly sensitive and efficient, requiring vanishingly small amounts of testing chemicals and biological material, like blood samples, to work. He used these particles to develop Achira’s first product: a toaster-sized box with cartridges of disposable sensors used to do a range of sophisticated tests, including precise calibrations of thyroid levels and fertility. When it launches early next year, it will be India’s first commercial microfluidic device. Dendukuri expects they will be snapped up by thousands of little mom-and-pop labs that would otherwise have to outsource samples for such tests to bigger city-based labs.

His next challenge was to use his box of microfluidic tricks to develop something even trickier: “point-of-care” devices for instant testing. These had to be even cheaper and easier to use, since they’d be meant for patients themselves, not just their doctors and nurses. The choice of silk as substrate instead of plastic, one of the reigning go-tos in microfluidics, was serendipitous: An employee’s cousin turned out to be a handloom weaver, and was happy to be recruited.

Dendukuri soon found that silk had a number of advantages over plastic, both in effectiveness and cost. Many careful experiments later, he realized that the versatile material also offered a possible solution to the trickiest of lab-to-market problems: scaling up and distributing cheaply and efficiently. “We source almost everything locally—the fabric, the looms, and the weavers,” says Dendukuri.

Once the silk yarns were coated in reagents and inks, weaving them was a single-shot operation. Which meant that fabric woven in a single eight-hour-shift, by a single hand-operated loom, could be used to make 100,000 sensors. With a mechanized loom, the company could turn out ten times as many. And then, it could drive down costs even further by setting up specialized units closer to the populations that need them, and cutting out cost-inflating middle-men.

These devices will ship next year once they’re officially approved—a smooth solution to a global problem.