Sensing danger in severe environments

MSE alumni Jason Gu and Jacob Melby and MSE Professor Bob Davis have developed a hydrogen sensor that can prevent catastrophic explosions in severe environments.  They, together with MSE Professor Lisa Porter, founded SenSevere LLC to produce hydrogen sensors for harsh environments, such as chlorine production cells and nuclear reactors. 

During the production of chlorine, high concentrations of hydrogen are produced and must be swept out of the system. If hydrogen is accidentally allowed to mix and react with chlorine, the reaction produces hydrochloric acid (HCl), which, in turn, produces so much heat that it often causes massive explosions.

The hydrogen sensor, which was developed at Carnegie Mellon, is vital in materials science because detecting hydrogen during chlorine production can prevent explosions and loss of life. SenSevere’s device is unique because it can go inside working chlorine production cells and endure the harsh chemical environment created by chlorine. Before this device, no other sensor on the market could withstand the corrosive environments generated during chlorine production.

“The importance of the sensor has to do with the robustness of the sensor itself,” said Gu. “Basically, the more chemically stable the materials that you’re using in your sensor, the less it will interact with its environment. The sensor enables us to be more flexible in terms of the things that we choose for it to interact with, because it itself is very stable.”

Besides chlorine production, Davis explained that the sensor can be used in nuclear reactors. Hydrogen buildup in nuclear reactors typically led to massive explosions because of high concentrations of hydrogen interacting with oxygen or water. Davis and Gu emphasize the importance of the SenSevere’s hydrogen sensor because it can provide sensing in environments that could never be sensed before.

This is where knowledge, understanding, and a little luck helped to create a device which could be brought to commercial fruition.

Bob Davis, Professor, Materials Science and Engineering, Carnegie Mellon University

“If you think about the inside of a nuclear reactor,” said Gu, “the further in you get, the less information you have about what’s going on, and the slower that information comes. If you’re at the very outside of the core, you can bring a handheld sensor in. But as you go further and further into the core, the information gets much more delayed and less accurate because you can’t send a person in, and other sensors don’t work as well in there.”

“The hydrogen sensor provides us with faster and more accurate information about some of these dangerous environments and processes that are present.”

The inspiration for the company’s device came from the team’s interest in Group-III nitride films and devices. For this project, they tested an aluminum gallium nitride (AlGaN) high-electron-mobility transistor (HEMT) to evaluate its capacity as a sensor material. Gu thought the transistor might be sensitive to hydrogen, so the team sought to test his hypothesis.

“We set up a laboratory in Wean Hall, and Gu and Melby began testing the transistor for hydrogen sensitivity at various concentrations, temperatures, and pressures,” said Davis. “And lo and behold, it turned out to be a really excellent sensor for hydrogen.”

“This is where knowledge, understanding, and a little luck helped to create a device which could be brought to commercial fruition.”