This sensore can sniff out hydrogen leaks

A tiny patch of an organic semiconductor, smaller than a nano-sized SIM card used in cell phones, may help detect dangerous hydrogen leaks. An international team of researchers has developed an organic hydrogen sensor, which relies on printable active polymer materials that respond to the presence of hydrogen at room temperatures. Further, once the sensing is done, it can reset to original conditions on its own, the scientists reported recently in Nature Electronics (go.nature.com/4kOaL6h).

Switching to a clean fuel such as hydrogen helps decarbonise key industry sectors ('Hydrogen plays an exciting role in decarbonisation'), but the material's combustive nature, low flammability – the ease with which it burns – and people's inability to smell it create safety concerns for its production, storage, transportation (All tanked up), and usage. Hydrogen's wide explosive range spans from 4% to 75%, making it extremely dangerous. Safe deployment calls for effective sensor technologies that detect leaks quickly and accurately. 

The hydrogen detection market is a robust one. According to the global market research agency Research and Markets, the global hydrogen detection market was worth $312 million in 2024 and is estimated to grow to $563 million by 2030, at a compound annual growth rate of 10.2%. There are different hydrogen sensor technologies, but most are bulky and consume significant units of power, making their widespread adoption problematic and expensive. Limited responsivity (the ability to respond to leaks) and selectivity (sensing only a chosen substance) also hinder applications. 

The organic sensor resolves these problems. The international team — consisting of researchers from the Indian Institute of Technology (IIT) Kharagpur; King Abdullah University of Science and Technology (KAUST), Saudi Arabia; the National Technical University of Athens, Greece; and The University of Manchester, U.K. — has devised a sensor with several advantages: high responsivity, rapid response time (of less than a second), and extremely low power consumption. 

The sensor is made by screen-printing a thin, organic semiconductor film called DPP-DTT on platinum electrodes of tiny dimensions — 10 mm x 6 mm x 0.7 mm. "(Its) sensing mechanism relies on an oxygen-hydrogen de/doping cycle process and is highly specific to hydrogen. The organic semiconductor is initially doped by oxygen, increasing its electrical conductivity. However, upon exposure to hydrogen, the doping process is reversed, and the conductivity of the materials reduces rapidly," says Thomas Anthopoulos, Professor of Materials Science at KAUST and The University of Manchester. "The surprising finding was that the de/doping process is fast and occurs at room temperature without resetting it upon sensing," he says.

Lightweight and ultrathin, it consumes little power while its performance is on a par with commercially available sensors. "Our organic hydrogen sensor has an estimated detection limit of 0.6 parts per million (ppm), far below the lower explosion limit of 4%, which equates to 40,000 ppm," says Anthopoulos, adding that the sensor can detect the tiniest of leaks. 

"Unlike conventional sensors, it operates efficiently at room temperature without requiring external heating, making it more energy-efficient and easier to integrate with integrated circuits," says Suman Mandal, a post-doc researcher at KAUST and the paper's first author. Mandal adds that the combination provides a cost-effective, eco-friendly, and scalable solution, significantly advancing hydrogen-sensing technology and contributing to a safer and more sustainable hydrogen economy. Anthopoulos believes such organic hydrogen sensors could lead to numerous new applications so far hindered by incumbent hydrogen sensors.

The work presents detailed materials and electrical characterisation results on a typical 'reducing type' hydrogen sensor, says S. Venugopal, Associate Professor in the Department of Chemical Engineering at the Indian Institute of Science (IISc), Bengaluru. He points out that the team has coupled the fabricated hydrogen sensor with bespoke electronics to show that it can be wirelessly monitored. 

But it is not devoid of hurdles. A 'litmus test' for such sensors is selectivity for hydrogen vis-à-vis hydrogen sulphide (H2S), which the study has not taken into account, Venugopal says. He adds that DPP-DTT responds to H2S at ppb (parts per billion) levels. "This will restrict its application space in oil and gas industries as well as the potential hydrogen economy infrastructure, such as pipelines or hydrogen refuelling stations... wherever the background H2S will be of the order of 10-100 ppb. But it may work well in situations where there are no gases such as H2S or methane," he adds.