Miniature Low-Power Sensor Revolutionizes Hydrogen and NO₂ Leak Detection

The IISER team identified nickel (Ni)—a far more affordable element from the same chemical group—as an equally promising candidate, costing roughly one-tenth the price of palladium.

Hydrogen is widely considered a clean fuel of the future, with applications in fuel cells, transportation, and industry. However, its highly flammable nature makes leak detection critical even at trace concentrations. At the same time, nitrogen dioxide (NO₂), often released from fossil fuel combustion in gas stoves or kerosene heaters, poses severe health risks even in minute amounts. Detecting these gases reliably, especially at room temperature and with minimal power consumption, has been a long-standing challenge—until now.

A research team at the School of Physics, IISER Thiruvananthapuram, supported by the Department of Science and Technology’s Nano Mission program, has developed a miniaturised, energy-efficient gas sensor capable of detecting trace hydrogen leaks and tiny concentrations of toxic NO₂. This breakthrough has potential to transform safety monitoring in clean energy, aerospace, defence, and environmental applications.

From Concept to Breakthrough

Traditional hydrogen sensors rely heavily on palladium (Pd), a costly metal with strong hydrogen affinity. While effective, Pd-based devices suffer from slow signal recovery and high production costs. The IISER team identified nickel (Ni)—a far more affordable element from the same chemical group—as an equally promising candidate, costing roughly one-tenth the price of palladium.

Their innovation centred on one-dimensional nickel oxide (NiO) nanostructures, such as suspended nanobeams and nanowires, functionalised with nickel nanoparticles and zinc oxide (ZnO) nanoparticles. NiO, a p-type semiconductor, and ZnO, an n-type semiconductor, form pn junctions at the nanoscale. These junctions are extraordinarily sensitive to environmental changes, enabling them to detect even a whiff of hydrogen through sharp changes in electrical conductivity.

Precision Fabrication and Scalable Methods

The team, led by Dr. Vinayak B. Kamble (IISER Thiruvananthapuram) and supported by Dr. Kusuma Urs MB (PhD student, IISER Thiruvananthapuram), Prof. Navakanta Bhat, and Mr. Krutikesh Sahu (both from CeNSE, IISc Bangalore), pursued two parallel fabrication strategies:

1. High-Precision Route – Using advanced semiconductor fabrication tools to sculpt suspended nanobeams of Ni and NiO with nanoscale precision.

2. Cost-Effective Route – Growing ZnO/NiO junctions via simple, scalable solution methods.

Both approaches yielded sensors that outperformed conventional devices—achieving high selectivity, fast response times, and room-temperature operation.

Applications Across Strategic Sectors These new sensors could:

• Detect hydrogen leaks in real time at fuel stations, in vehicles, and at industrial facilities.

• Monitor volatile organic compounds (VOCs) in urban environments.

• Support safe and widespread adoption of hydrogen fuel, aiding India’s green transition goals.

• Be deployed in aerospace and defence systems, thanks to their lightweight and low-power design.

With their scalability already demonstrated, the sensors are poised to become integral components in the Internet of Things (IoT) ecosystem, enabling precise environmental monitoring and predictive safety measures.

Next-Generation AI-Assisted Sensors

The team’s work has evolved beyond single-gas detection. In a follow-up project, they developed oxide semiconductor arrays composed of NiO, CuO, and ZnO sensors, generating rich datasets for AI-assisted gas sensing. Their latest advancement features ultra-low-power and self-powered devices using atomically thin heterostructures fabricated through CMOS-compatible methods. These next-gen sensors can be tailored to selectively detect either hydrogen or NO₂ simply by adjusting deposition conditions—offering unprecedented versatility in environmental safety technology.

A Leap Towards Safer, Cleaner Energy

By combining affordability, miniaturisation, low energy consumption, and high sensitivity, IISER Thiruvananthapuram’s sensor technology addresses a pressing gap in clean energy safety and urban air quality monitoring. The research, published in leading journals such as Sensors and Actuators B, ACS Applied Electronic Materials, and Small, represents a decisive step toward safer hydrogen infrastructure and smarter, AI-driven environmental sensing.