University of Utah electrical engineers fabricated the smallest plasma transistors that can withstand the high temperatures and ionizing radiation found in a nuclear reactor.
Such transistors someday might enable smartphones that take and collect medical X-rays on a battlefield, and devices to measure air quality in real time.
“These plasma-based electronics can be used to control and guide robots to conduct tasks inside the nuclear reactor,” says Massood Tabib-Azar, a professor of electrical and computer engineering.
“Microplasma transistors in a circuit can also control nuclear reactors if something goes wrong, and also could work in the event of nuclear attack.” The most commonly used type of transistor is called a metal oxide semiconductor field effect transistor, or MOSFET.
Plasma-based transistors, which use charged gases or plasma to conduct electricity at extremely high temperatures, are employed currently in light sources, medical instruments and certain displays under direct sunlight (but not plasma TVs, which are different). These microscale devices are about 500 microns long, or roughly the width of five human hairs. They operate at more than 300 volts, requiring special high-voltage sources. Standard electrical outlets in the United States operate at 110 volts.
The new devices designed by the University of Utah engineers are the smallest such microscale plasma transistors to date. They measure 1 micron to 6 microns in length, or as much as 500 times smaller than current state-of-the-art microplasma devices, and operate at one-sixth the voltage. They also can operate at temperatures up to 1,450 degrees Fahrenheit. Since nuclear radiation ionizes gases into plasma, this extreme environment makes it easier for plasma devices to operate.
“Plasmas are great for extreme environments because they are based on gases such as helium, argon and neon that can withstand high temperatures,” says Tabib-Azar. “This transistor has the potential to start a new class of electronic devices that are happy to work in a nuclear environment.”