this will enable robots and computers to keep working in space, inside damaged nuclear power plants or after an atomic attack.
The researchers showed the devices kept working despite intense ionizing radiation and heat by dipping them for two hours into the core of the University of Utah’s research reactor.
Ionizing radiation can quickly fry electronic circuits, so heavy shielding must be used on robots such as those sent to help contain the meltdowns at the Fukushima Daiichi nuclear power plant after Japan’s catastrophic 2011 earthquake and tsunami.
Massood Tabib-Azar, a professor of electrical and computer engineering at the University of Utah and the Utah Science Technology and Research initiative, explained: “Robots were sent to control the troubled reactors [in Japan], and they ceased to operate after a few hours because their electronics failed.
“We have developed a unique technology that keeps on working in the presence of ionizing radiation to provide computational power for critical defense infrastructures.”
He said, “Our devices also can be used in deep space applications in the presence of cosmic ionizing radiation, and can help robotics to control troubled nuclear reactors without degradation.”
Tabib-Azar’s work was funded by the Defense Advanced Research Projects Agency (DARPA), a Defense Department subdivision that Iran has called a spy agency although it has operated for half a century funding cutting-edge technology.
The new devices are “logic gates” that perform logical operations such as “and” or “not” and are a type of device known as MEMS or micro-electro-mechanical systems. Each gate takes the place of six to 14 switches made of conventional silicon electronics.
Development of the new logic gates was reported in the journal Sensors and Actuators. The research was conducted by Tabib-Azar, University of Utah electrical engineering doctoral student Faisal Chowdhury and computer engineer Daniel Saab at Case Western Reserve University in Cleveland.
Tabib-Azar said, “If there is a nuclear event, we need to be able to have control systems, say for radars, to be working to protect the nation. There are lots of defense applications both in peacetime and wartime that require computers that can operate in the presence of ionizing radiation.”
Current radiation-resistant technologies fall into two categories: silicon-oxide semiconductor electronics shielded with lead or other metals, and the use of different materials that inherently resist radiation.
“Electronic materials and devices by their nature require a semiconducting channel to carry current, and the channel is controlled by charges,” Tabib-Azar says. Radiation creates current inside the semiconductor channel, and “that disrupts the ability of the normal circuitry to control the current, so the signal gets lost.”
He says the MEMS logic gates are not degraded by ionizing radiation because they lack semiconducting channels. Instead, electrical charges make electrodes move to touch each other, thus acting like a switch.
MEMS have their drawbacks, which Tabib-Azar believes is why no one until now has thought to use them for radiation-resistant circuits. Silicon electronics are 1,000 times faster, much smaller, and more reliable because they have no moving parts.
But by having one MEMS device act as a logic gate, instead of using separate MEMS switches, the number of devices needed for a computer is reduced by a factor of 10 and the reliability and speed increases, Tabib-Azar said.
