Covid-19 breakthrough: IIT Guwahati invents low-cost clay test to detect virus faster and more accurately

In a breakthrough that blends age-old earth sciences with modern virology, researchers at the Indian Institute of Technology (IIT) Guwahati have uncovered a new way to detect SARS-CoV-2 — the virus behind COVID-19 — using clay. Their method, as unassuming as watching sediment settle in saltwater, hinges on how viral presence alters clay particle behaviour, offering a novel, low-cost alternative to conventional testing.

The researchers observed that in the presence of the virus, inter-particle forces among clay particles shift, changing the sedimentation rate in saline solutions. "Due to changes in inter-particle forces of clay in the presence of the virus, the sedimentation rate of the clay-electrolyte system changed," the authors wrote in their study published in Applied Clay Science.

Calling it a "simple and affordable" approach, the team positioned it against current detection methods that are either too complex or insufficiently accurate. "Current methods, such as Polymerase Chain Reaction (PCR), are highly sensitive but time consuming and require heavy equipment. Similarly, the antigen testing is fast but lacks accuracy, while antibody testing is used after the infection has occurred, highlighting limitations at various levels," said lead author T.V. Bharat, a professor in IIT Guwahati’s civil engineering department.

He noted that many existing tools fall short in resource-constrained settings or during widespread outbreaks, gaps that became glaring during the COVID-19 crisis.

The team turned to Bentonite clay, known for its ability to absorb pollutants and heavy metals, due to its chemical properties. "Previous studies have shown that clay particles can bind with viruses and bacteriophages, making it a promising material for virus detection," Bharat added.

In the study, they tested how particles of Bentonite clay behaved in a saltwater solution with viral material. The experiments, carried out at room temperature and neutral pH, showed that the Coronavirus surrogate and Infectious Bronchitis Virus (IBV) attached to the negatively charged clay surfaces, affecting how the particles settled.

According to Bharat, the result is “a faster, more affordable, and an accurate” diagnostic tool, which can be implemented even in low-resource environments. “It’s as simple as watching sand settle in water,” he said.

This technique, he emphasised, could transform how viral outbreaks are detected and managed, especially where lab infrastructure is minimal.

Meanwhile, India’s COVID-19 numbers continue to inch slowly towards the 6,000-mark. Active cases now stand at 5,755, with 73 new infections reported in Delhi over the past 24 hours, pushing the capital’s total active caseload to 665. Four deaths — one each in Madhya Pradesh, Maharashtra, Kerala and Tamil Nadu — were reported during the same period. Kerala currently has the highest number of active cases at 1,806, followed by Gujarat (717), Maharashtra (577), and Karnataka (444). Health officials continue to monitor developments and urge preventive measures.