Researchers at the Indian Institute of Technology Madras (IIT Madras) have developed a chip-based device capable of detecting bacterial resistance to antibiotics within three hours. The device, described as affordable and simple to use, has been published in Nature Scientific Reports, a peer-reviewed journal from the Nature Portfolio.
The microfluidic device, called ε-µD, is based on screen-printed carbon electrodes embedded in a microfluidic chip. Unlike other modern testing methods that require expensive materials and skilled technicians, the device uses electrochemical signals to assess whether bacteria are resistant or susceptible to antibiotics.
According to the researchers, this approach makes the device suitable for smaller clinics and rural healthcare centres. They said it could support early diagnosis and guide appropriate treatment of bacterial infections, particularly in areas with limited laboratory facilities.
Antimicrobial resistance (AMR) has been identified by the World Health Organization as one of the top ten threats to global health. Estimates suggest that nearly 4.95 million deaths worldwide in 2019 were associated with bacterial AMR.
Current Antimicrobial Susceptibility Testing (AST) methods usually take 48 to 72 hours, as they involve growing bacterial cultures and checking their response to antibiotics. This delay often results in the use of broad-spectrum antibiotics, contributing further to resistance.
The IIT Madras team said ε-µD offers a faster alternative by using ‘Electrochemical Impedance Spectroscopy’. The device measures changes in electrical signals as bacteria grow in a nutrient solution. If bacteria survive despite the presence of an antibiotic, the electrical properties of the solution change. If they are killed, the signal remains stable.
Professor Subramaniam Pushpavanam from the Department of Chemical Engineering said the specially prepared nutrient solution played a dual role by supporting bacterial growth and enhancing the sensitivity of electrical signals. He added that the device has potential impact for patients in intensive care units, where rapid testing could help doctors prescribe the correct treatment. The team is carrying out clinical validation in collaboration with the IITM Institute Hospital and is planning commercialisation through Kaappon Analytics India Private Limited, a startup incubated at IITM Research Park.
Dr Richa Karmakar from the Department of Biotechnology said the device uses a metric called Normalised Impedance Signal (NIS) to differentiate between resistant and non-resistant bacterial strains in a matter of hours.
The researchers tested ε-µD on E. coli and B. subtilis using two antibiotics with different modes of action — ampicillin, which kills bacteria, and tetracycline, which prevents growth. The device was able to detect susceptibility profiles within three hours. It was also tested on urine samples spiked with E. coli, where it successfully identified resistance to tetracycline, demonstrating its potential use in clinical diagnostics.
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