Hall-effect sensors functioning up to at least 600 degrees Celsius

Hall-effect sensors detect and monitor magnetic fields. For many potential applications across aviation and aerospace industries, these sensors need to be tested for extreme operating environments, where they may be exposed to high temperatures or radiation.

Alpert et al. study the durability of a Hall-effect sensor and identify ways to optimize its use. They tested the sensor at temperatures up to 600 degrees Celsius for 12 hours.

After the trial, the gallium nitride-based Hall-effect sensor recovered from the extreme temperature and was able to perform at nearly its original sensitivity. Although the sensor exhibited decreased voltage-scaled sensitivity as the temperature increased, the device showed stable current-scaled sensitivities as the temperature rose.

The authors chose the wide bandgap semiconductor, gallium nitride, because it has previously been demonstrated to operateat up to 1000 degrees in a vacuum; making it ideal for aerospace applications.

“We only stopped testing at 600 degrees because that was the limit of our test equipment capability. Ideally, it would be great if we could test at higher temperatures to see when and how the sensors actually fail,” said author Hannah Alpert.

The authors have begun a second phase of testing on the sensor under other space-relevant conditions, such as intense radiation exposure and extremely low temperatures.

“We are working on accelerated aging and reliability testing of these devices to characterize their lifetime and understand their failure mechanisms under exposure to harsh environmental conditions for long durations,” said Alpert.

Source: “Sensitivity of 2DEG-based hall-effect sensors at high temperatures,” by H. S. Alpert, C. A. Chapin, K. M. Dowling, S. R. Benbrook, H. Köck, U. Ausserlechner, and D. G. Senesky, Review of Scientific Instruments (2020). The article can be accessed at https://doi.org/10.1063/1.5139911 .