Sweat Based Inflammation Test Could Cut Needles And Lab Visits

Hyderabad: A painless sweat test for inflammation could reduce hospital blood draws for people with heart disease and chronic infections. Researchers at BITS Pilani Hyderabad have now built a gold film sensor that reads a key inflammation marker from sweat instead of blood.

‘C reactive protein’, or CRP, rises when the body is fighting infection or when blood vessels are under stress. Doctors already use CRP blood tests to track sepsis and cardiovascular risk, but they need needles, labs and trained staff.

“We asked a simple question,” says lead author and PhD scholar Sonal Fande from the MEMS, Microfluidics and Nanoelectronics Lab at BITS-Pilani Hyderabad. “Can we read CRP from sweat using something thin, flexible and cheap enough to sit in a wearable patch?”

The team deposited a nanometre thick gold layer on a flexible plastic sheet using a standard thin film method that is already common in electronics. They then used a special covalent linker coating called AnteoBind to attach CRP antibodies in a single step, giving the sensor a stable and well organised “sensing layer”. When CRP from sweat binds to these antibodies, it changes the electrical signal of the gold film in a way the device can measure.

In lab tests, the sensor detected CRP in the range of 1 to 35 nanograms per millilitre, with a detection limit of 0.27 nanograms per millilitre. “It kept about 90 per cent of its original response after 30 days and showed good consistency across multiple devices. In artificial and real human sweat samples, the measured values were within about 96 to 102 per cent of the expected CRP levels.,” he explained.

According to principal investigator Sanket Goel, the long term goal was a soft, skin worn system. “If you can turn this into a small sweat patch that talks to a phone, someone with cardiac risk or an autoimmune condition could be checked at home instead of waiting for a lab slot,” he says. The team estimates that each sensor presently costs about ₹150 to ₹200 to fabricate, with scope to push this below ₹30 at scale.

The work is reported in ‘ACS Applied Nano Materials’ under the title “Covalent linker functionalised nanometer thick gold film electrodes for noninvasive electrochemical C reactive protein detection.”