Robot with caterpillar-like legs to deliver drugs inside human body

Scientists have created tiny robot with 'caterpillar'-like legs that can carry drugs inside the human body. The robot can move efficiently inside surfaces within the body lined with, or entirely immersed in, body fluids such as blood or mucus, the scientists claimed.

The caterpillar-like robot has hundreds of pointed legs, measuring less than a millimetre. Researchers studied the leg structures of hundreds of ground animals, including those with two, four, eight or more legs, in particular the ratio between leg-length and the gap between the legs, according to researchers from the City University of Hong Kong (CityU).

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"Most animals have a leg-length to leg-gap ratio of 2:1 to 1:1. So we decided to create our robot using 1:1 proportion," said Shen Yajing, an assistant professor at CityU, who led the research.

The robot's body thickness measures approximately 0.15 mm, with each conical leg measuring 0.65 mm long and the gap between the legs measuring approximately 0.6 mm, making the leg-length-to-gap ratio around 1:1.

Laboratory tests showed that the multi-legged robot has 40 times less friction than a limbless robot in both wet and dry environment. Tests showed that it was capable of carrying a load 100 times heavier than itself, a strength comparable to an ant, one of the strongest creatures in nature. 

The robot is fabricated with a silicon material called polydimethylsiloxane (PDMS) embedded with magnetic particles which enables it to be remotely controlled by applying electromagnetic force.

"Both the materials and the mutli-leg design greatly improve the robot's hydrophobic property. Besides, the rubbery piece is soft and can be cut easily to form robots of various shapes and sizes for different applications," said Wang Zuankai from CityU.

"The rugged surface and changing texture of different tissues inside the human body make transportation challenging. Our multi-legged robot shows an impressive performance in various terrains and hence open wide applications for drug delivery inside the body," said Wang.

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When facing an obstacle ten times higher than its leg length, the robot, with its deformable soft legs, is capable to lift up one end of its body to form an angle of up to 90-degree and cross the obstacle easily. By increasing the electromagnetic frequency the robot can increase its speed.

Before conducting further tests in animals and eventually in humans, the research teams are working on developing and refining their research in three aspects, namely finding a biodegradable material, studying new shapes, and adding extra features to it.

(With inputs from agencies)