Palladium coating on the side walls of polymer nano lattice
Application after production of sensitive light transmittance change film
Remote access is possible when power supply is not smooth


Hydrogen gas is attracting attention as a next-generation eco-friendly energy source, but continuous monitoring is essential due to the high risk of explosion in the event of a leak. However, existing hydrogen detection devices require continuous power supply, which limits their use for long periods of time in various wireless environments.

A joint research team of Professor In-Kyu Park of the Department of Mechanical Engineering at the Korea Advanced Institute of Science and Technology (KAIST), Professor Jun-Bo Yoon of the Department of Electrical and Electronic Engineering, and Professor Jun-Seok Noh of Pohang University of Science and Technology (POSTECH) announced on the 18th that they have developed a wireless hydrogen detection sensor that can operate stably for long periods of time without an external power supply.

The research team discovered that when they asymmetrically coated one side wall of a flexible polymer nano grating with palladium (Pd), the polymer nano grating mechanically bent as the palladium expanded when it absorbed hydrogen molecules, causing a change in light transmittance, similar to a kind of "curtain."

By utilizing this phenomenon, if a sensing film is attached to the surface of a solar cell, the light reaching the solar cell is blocked when exposed to hydrogen gas, which leads to a change in the solar cell output, allowing the concentration of hydrogen gas to be precisely detected without an external power supply.

The wireless hydrogen detection sensor developed this time can accurately predict the concentration of hydrogen gas without an external power source, and is expected to be utilized in various wireless remote environments that utilize hydrogen.

To maximize the performance of the sensor, the palladium coating conditions (incident angle) were optimized through numerical simulations to achieve high sensor sensitivity even for low-concentration hydrogen gas of 0.1%, and it was also verified that a stable signal was maintained even under repeated hydrogen gas leaks and humidity changes.

The research team also presented a prototype that can remotely check the detected hydrogen concentration using a smartphone by mounting the developed wireless hydrogen sensor on a mobile device, thereby increasing its usability in an actual wireless environment.

The prototype is equipped with a solar cell that is used for hydrogen detection, as well as an additional solar cell to compensate for changes in ambient light intensity, allowing real-time compensation and transmitting a signal to a smartphone via Bluetooth. The smartphone app sounds an alarm when the hydrogen gas concentration exceeds the explosive limit of 4%.

Professor Park In-gyu said, “The developed prototype is expected to greatly increase usability in remote areas where sensor power supply is not smooth, and contribute to the safe use of hydrogen, a next-generation energy source.”

Meanwhile, the results of this study, which was conducted with the support of the National Research Foundation of Korea's Leading Research Center Support Project and the Nano and Material Technology Development Project, were published in the December 2020 issue of the international academic journal 'ACS Nano'.