SenSevere: sensing danger in severe environments

Carnegie Mellon Materials Science and Engineering (MSE) alumni Jason Gu and Jacob Melby and MSE Professor Bob Davis have developed a hydrogen sensor that researchers can use in severe environments to sense and prevent catastrophic explosions. After Gu, Melby, and Davis created the hydrogen sensor at Carnegie Mellon, they founded SenSevere LLC along with MSE Professor Lisa Porter. SenSevere LLC is a company that produces hydrogen sensors for different severe environments, such as chlorine production cells and nuclear reactors.

The trio first developed the sensor to detect the presence of hydrogen in chlorine production. During the production of chlorine, high concentrations of hydrogen are produced and must be swept out of the system. According to Davis, if hydrogen is, by accident, allowed to mix and react with chlorine, the reaction produces hydrochloric acid (HCl), which, in turn, produces so much heat that it quite often causes significant, massive explosions.

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

“The importance of the sensor has to do with the robustness of the sensor itself,” said Gu. “From a very basic point of view, the more chemically stable the materials that you’re using in your sensor, the less it will interact with its environment. The sensor has basically enabled 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 other severe environments such as nuclear reactors. Hydrogen buildup in nuclear reactors typically led to massive explosions because high concentrations of hydrogen interact with oxygen or water. For this reason, Davis and Gu emphasize the importance of SenSevere’s hydrogen sensor because it can be used to 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, Founder, SenSevere LLC

“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 actually 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 then 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 sensor device came from the team’s interest in Group-III nitride films and devices. For this project, they studied and 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.”