Early detection of viral infections often depends on blood-based antibody tests that require needles, laboratory processing, and long turnaround times. To overcome these limitations, researchers have developed ultra-sensitive wearable biosensors that can detect antibodies against pathogens such as SARS-CoV-2 and influenza directly from interstitial fluid in just 10 minutes.

The sensors, created by an interdisciplinary team at the University of Pittsburgh (Pittsburgh, PA, USA), use viral antigens attached to carbon nanotubes—structures 100,000 times thinner than a human hair—to “capture” circulating antibodies. Once binding occurs, the nanotubes’ electrical properties shift, enabling antibody detection at levels nine orders of magnitude more sensitive than standard ELISA tests.

Because interstitial fluid contains many of the same proteins found in blood, the wearable format eliminates the need for blood draws and complex laboratory infrastructure. The platform can detect antibodies against SARS-CoV-2 and H1N1 influenza and requires only half a volt of power, returning results at the point of care within minutes.

The researchers say the approach, presented in Analytical Chemistry, could support infection diagnosis, assess vaccine effectiveness, or guide booster decisions by allowing rapid, repeated monitoring of antibody levels. Its extreme sensitivity also makes it suitable for expansion into continuous monitoring systems using microneedle array patches—painless adhesive devices that sample interstitial fluid without penetrating nerve-rich tissue. Such systems could one day help personalize dosing of therapeutic antibodies for autoimmune diseases or cancer and detect early immune responses to allergens or new infections.

“Typically, the way that's done today is you take a blood sample, you send it to the lab, they do an assay and then you get the results back maybe a day later,” said research scientist Stephen Balmert. “One of the advantages with these sensors is the idea of point-of-care diagnostics. You can apply them, you can take a sample and you can get the results almost instantaneously — no complex lab infrastructure required.”

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