Image created by Dr. Michael J. Miller
Indian Institute of Technology Madras (IIT Madras) Researchers have developed an innovative and affordable microfluidic device that can rapidly determine whether bacteria are resistant or susceptible to antibiotics.
Unlike many modern techniques that rely on costly metals, complex fabrication processes, or require highly skilled technicians, this lab-on-chip device, known as ‘ε-µD’ is based on screen-printed carbon electrodes embedded in a simple microfluidic chip. This approach makes the device not only economical but also suitable for deployment in smaller clinics and rural healthcare centres.
Designed for speed, sensitivity, and ease of use, it holds strong potential for early diagnosis and better treatment of bacterial infections, particularly in regions with limited access to advanced laboratory infrastructure. The ε-µD device can deliver results within three hours and is based on ‘Electrochemical Impedance Spectroscopy’.
Antimicrobial resistance (AMR) is one of the most pressing challenges facing global healthcare systems today. The World Health Organization (WHO) has identified AMR as one of the top ten threats to global health, and estimates suggest that nearly 4.95 million deaths worldwide in 2019 were associated with bacterial AMR.
The burden is especially high in low- and middle-income countries, where diagnostic facilities are limited and infections often go untreated or are improperly managed.
Antimicrobial Susceptibility Testing (AST) is an important method used to identify which antibiotics will work against a specific infection. It helps doctors choose the right treatment and avoid the misuse of antibiotics, which is a major cause of AMR.
However, traditional AST methods, which involve growing bacterial cultures and observing their response to antibiotics, are labour-intensive and typically take 48 to 72 hours. This delay can lead to the use of broad-spectrum antibiotics as a stopgap, which in turn exacerbates the resistance problem.
To address these limitations, the IIT Madras team developed ε-µD — a cost-effective phenotypic testing device that uses electrochemical signals to assess bacterial growth and antibiotic susceptibility. This device meets several key criteria outlined by the WHO, including affordability, speed, ease of use and reliability. By addressing these priorities, ε-µD takes a significant step toward making antimicrobial susceptibility testing more accessible, especially in low-resource settings.
This Research has been published in the prestigious Nature Scientific Reports (https://doi.org/10.1038/s41598-024-84286-3), a peer-reviewed, open-access scientific mega journal published by Nature Portfolio (part of Springer Nature), covering all areas of the natural sciences. The paper was co-authored by Saranya Gopalakrishnan (Director Technology Innovation, Kaappon Analytics India Pvt Ltd, a startup incubated in IITM Research Park, kaapponanalytics@gmail.com) and Diksha Mall, Research Scholars from IIT Madras alongside IIT Madras faculty Prof. Subramaniam Pushpavanam and Dr. Richa Karmakar.
Elaborating on this research, Prof. S Pushpavanam, Y B G Varma Institute Chair Professor, Department of Chemical Engineering, IIT Madras, said, “An important aspect of our device is the use of a specially prepared nutrient solution that serves a dual purpose. It not only supports bacterial growth, which is essential for testing, but also enhances the sensitivity of the electrical signals we use for detection. As the bacteria grow, they cause measurable changes in the electrical properties of the solution, which our system can accurately track.”
Explaining how this technology can be taken to the real world and possible initiatives in this direction, Prof. S Pushpavanam added, “This approach will make a real impact on patients in Intensive Care Units, who may be suffering from complications due to bacterial infections. This will help the doctors prescribe the right treatment and can be life-saving. Currently, we are doing clinical validation in collaboration with the IITM Institute hospital. After rigorous clinical validation, we are planning to commercialise this through our startup, Kaappon Analytics India Private Limited.”
Further, Dr. Richa Karmakar, Assistant Professor, Department of Biotechnology, IIT Madras, added, “The device monitors how the electrical signal changes over time to determine whether bacteria are continuing to grow in the presence of an antibiotic. If the bacteria are resistant, they multiply despite the drug, and this activity causes a distinct change in the electrical signal. In contrast, if the bacteria are killed by the antibiotic, their growth is inhibited and the signal remains relatively unchanged. A metric called ‘Normalized Impedance Signal’ (NIS) developed by the researchers allows clear differentiation between resistant and non-resistant bacterial strains in a matter of hours.”
The researchers tested the device on two types of bacteria - gram-negative E. coli and gram-positive B. subtilis. They used two antibiotics with different modes of action — ampicillin, which kills bacteria and tetracycline, which prevents them from growing — to confirm the device’s ability to detect both kinds of responses. The ε-µD was able to detect susceptibility profiles within three hours.
In an important demonstration of real-world applicability, the team also tested the device on urine samples spiked with E. coli and successfully identified resistance to tetracycline, showing the potential of this device in clinical diagnostics.