BEIJING -- Thanks to a Chinese team's innovation, the colony of microbots from Disney's animated feature "Big Hero 6" is inching closer to reality.

At a laboratory in Beijing, a nimble, tiny bionic robot effortlessly weaved through its surroundings. Finding itself in a tight "cul-de-sac," the insect-scale machine swiftly backed out with small steps.

Professor Yan Xiaojun and his colleagues from Beihang University crafted the 2-cm-long insect robot, which weighs less than two grams and boasts a vertical projection area about the size of two fingernails.

Scaling down a robot to the size of an insect is more challenging than constructing their larger counterparts, as machines the size of bees cannot be equipped with conventional motors. Therefore, the search for a miniature power system has long been a difficult quest for global researchers.

"Cutting ties with an external power source means you have to integrate batteries and circuit boards into the robot. However, the additional load rendered it immobile," said Liu Zhiwei, a previous doctoral student of Yan's and now an associate professor at Beihang University.

In 2009, Yan noticed a fascinating occurrence: beyond a certain threshold, direct current voltage elicited sustained vibrations, a phenomenon typically associated with alternating current. That moment kept replaying in his mind, hinting at a potential application, such as the wings of a tiny drone.

It wasn't until 2017 that Yan embarked on the design of an insect-sized robot capable of movement without an external power supply. However, over the subsequent three years, his team explored dozens of body designs and fine-tuned parameters extensively, yet the robot remained stubbornly rooted to the spot.

To initiate the locomotion of his robotic insect, Yan scrutinized the gaits of beetles, grasshoppers, wild horses and rabbits.

It was the leopard's bounding and running that ultimately sparked the inspiration, and the team finally designed a new generation of biomimetic robotic insects "BHMbot" capable of ultrafast untethered running at a speed faster than cockroaches and with a better turning agility.

In a study published last month in the journal Science Advances, they reported an updated version of the robot that is capable of swift forward and backward movements and can execute intricate running paths under wireless control.

A good invention arises typically from a flash of inspiration followed by a great deal of hard investigation. It has been 15 years since Yan started on his research into tiny robots, but his efforts paid off.

In experiment, BHMbot can go through narrow spaces and reach specified locations to execute special tasks.

Via a commercial MEMS microphone, it can successfully collect SOS sound signals of a Bluetooth speaker buried by building blocks, and the sound data is then transmitted to a computer and converted to real sound, according to Liu.

The BHMbot can also go through the narrow passage between two stator blades of a civil turbofan engine and the tailbone of a turbojet engine. Mounted with micro cameras at millimeter scale, it might capture internal images of aero engines in the future.

These diminutive robots have promising applications in areas like disaster search and rescue, as well as in the inspection of mechanical equipment structures, said Yan.

The robotic insects are also poised for a takeoff in the future. "Our ultimate goal is to develop flapping-wing micro-drones that can fly like bees," added Yan.