A Robotic Millipede That Delivers Drugs

Researchers in Hong Kong have invented a tiny robot with soft caterpillar-like legs that can cross obstacles inside the body and carry heavy loads.

AsianScientist (Oct. 9, 2018) – In a study published in Nature Communications, a team of scientists has developed a tiny, soft robot with caterpillar-like legs capable of carrying heavy loads and adapting to a variety of environments inside the body.

Small, soft robots are gaining attention around the world for their potential uses in biomedicine. However, being able to control the robot’s movements inside the body can be challenging.

In the present study, researchers at the City University of Hong Kong (CUHK) designed a miniature robot with multiple legs that can move efficiently on the inner surfaces of the body. Made of polydimethylsiloxane embedded with magnetic particles, the robot can be remotely controlled by applying an electromagnetic force. It can move in both a flap propulsion pattern—where it uses its front feet to flap forward—and in an inverted pendulum pattern, by swinging its body and standing on left and right feet alternately.

The multi-legged design was chosen after the researchers studied the leg structures of hundreds of ground animals, including those with two, four, eight or more legs. They paid particular attention to the ratio between leg length and the gap between the legs.

“Most animals have a leg-length to leg-gap ratio of 2:1 to 1:1. So we decided to create our robot using a 1:1 proportion,” said Assistant Professor Shen Yajing of CUHK’s department of biomedical engineering, who led the research.

The researchers showed that their multi-legged robot experiences 40 times less friction than a limbless robot in both wet and dry environments. They further proved that the robot can traverse obstacles ten times higher than its leg length by lifting one end of its body to form an angle of up to 90°. The robot’s movement can also be sped up by increasing the frequency of the electromagnetic field applied.

Furthermore, the researchers demonstrated that the robot was capable of carrying a load 100 times heavier than itself, equivalent to a human lifting a 26-seater mini-bus.

“Its strong carrying capability, efficient locomotion and good obstacle-crossing ability make this milli-robot suitable for delivering drugs to a designated spot through the digestive system, or for carrying out medical inspection,” said Shen.

The article can be found at: Lu et al. (2018) A Bioinspired Multilegged Soft Millirobot That Functions in Both Dry and Wet Conditions.


Source: City University of Hong Kong.
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