DJI might have just found the most low-tech solution to a problem involving some of its most high-tech drones. 

Coronavirus epidemic prevention units in China have been using thermal-imaging drones to remotely check residents’ temperatures. So DJI took steps to improve the precision of measurements taken using the thermal camera on the Mavic 2 Enterprise Dual drone. Its tool? A humble cotton swab.

This simple cotton swab reduced DJI’s thermal imaging error margin to half a degree Celsius. (Picture: DJI)

DJI’s engineers found that sticking a cotton swab on their drones improves the accuracy of measuring a person's temperature by acting as a reference for calibrating the thermal imaging camera. Whereas accuracy could previously be off by as much as 4˚ to 5˚ Celcius (7.2˚ to 9˚ Fahrenheit), the swab reduces the margin of error to just 0.5˚ Celsius (0.9˚ Fahrenheit) under standard conditions, the company said.

The Mavic 2 Enterprise Dual drone is equipped with a FLIR Lepton thermal microcamera, but it was created for industrial use, meaning it wasn't made to measure body temperature. The cotton swab turned out to be the key to improving the camera’s accuracy, though DJI still doesn’t recommend using it for this purpose.

DJI said the cotton swab is an emergency solution created by their engineering team in three days. The company told us that they still recommend using professional medical equipment, but it’s also trying to find new ways for their tech to fight the spread of the deadly Covid-19 disease.

This is how DJI’s thermal view looks when their drones aren’t chasing people who might be infected with the coronavirus. (Picture: DJI)

When the drone finds someone who is feverish, the temperature abnormality is displayed through the UAV remote control screen, said Zhang Xiaonan, head of DJI Enterprise.

DJI’s drones have so far been used for remote temperature detection in many communities and at road checkpoints. But that’s not the only way drones are proving useful in the battle against the coronavirus. UAVs have also been used for spraying disinfectant over roads, helping with the construction of Wuhan’s temporary coronavirus hospitals and dispersing public gatherings -- including using a mounted megaphone to scold people for not wearing masks.