Although ice formation on the wings is a major cause of aircraft crashes, that ice must still mainly be spotted by eye – a process that’s subject to human error. A new sensor could change that, however, as it uses microwaves to instantly detect the formation of ice that may not be visible to pilots or ground crews.
Developed at the Okanagan Campus of Canada’s University of British Columbia, the device is known as a planar microwave resonator sensor. Basically consisting of metal deposited on a thin sheet of plastic, it’s robust enough to stand up to exposure to the elements, plus it’s easy and inexpensive to manufacture.
In a nutshell, it works by measuring how the resonant frequency, amplitude and scattering pattern of emitted microwaves are altered by any water, frost or ice that may be present on its surface. As a result, in lab tests, it was able to detect frost formation within a matter of seconds of its being cooled below freezing.
By contrast, human observers couldn’t see any frost until the sensor had sat at a temperature of -10 ºC (14 ºF) for about two minutes. And as the researchers point out, that was on a small sample within a lab – spotting all of the ice on an entire wing in an outdoor setting would be considerably harder.
As an added bonus, the technology is able to detect when ice has reverted back to liquid water, so it could also be used to confirm that de-icing operations have worked successfully.
“[The sensors] can detect when water hits the wing, track the phase transition from water to ice, and then measure the thickness of the ice as it grows, all without altering the aerodynamic profile of the wing,” says Asst. Prof. Mohammad Zarifi, who led the project along with Asst. Prof. Kevin Golovin. “The radiofrequency and microwave technology can even be made wireless and contactless. I wouldn’t be surprised if airlines start adopting the technology even for this upcoming winter.”
A paper on the research, which also involved graduate students Benjamin Wiltshire and Kiana Mirshahidi, was recently published in the journal Sensors and Actuators B: Chemical.