IIT Madras develops low-cost chip device for antibiotic resistance test

The IIT Madras team has designed a low-cost chip-based device that can detect antibiotic susceptibility in under three hours, helping fight antimicrobial resistance in low-resource settings

The 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 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 makes the device economical and 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 improved 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.

 

“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,” said S Pushpavanam, Y B G Varma Institute Chair Professor, Department of Chemical Engineering, IIT Madras.

 

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 10 threats to global health, with estimates suggesting 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 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 resistance.

 

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 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 doctors prescribe the right treatment and can be life-saving. Currently, we are conducting clinical validation in collaboration with the IITM Institute Hospital. After rigorous validation, we plan to commercialise this through our startup, Kaappon Analytics India,” said Pushpavanam.

 

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 their growth. The ε-µD was able to detect susceptibility profiles within three hours. In a 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 its potential in clinical diagnostics.

 

The research has been published in Nature Scientific Reports, 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), and Diksha Mall, research scholar, alongside IIT Madras faculty members Pushpavanam and Richa Karmakar.

 

“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 ‘normalised impedance signal’ (NIS), developed by the researchers, allows clear differentiation between resistant and non-resistant bacterial strains in a matter of hours,” said Karmakar.