This article details information about a research project from the City University of Hong Kong (CityU).

Researchers and medical professionals are always on the lookout for new ways to deliver life-saving and necessary drugs to their patients.

Since pills can help better diagnose cancer and track medications, why not robots, too?

The City University of Hong Kong developed a miniature delivery robot for this purpose. But how does it work and why compare it to a caterpillar?

How a Caterpillar Robot Came to Fruition

You know how some insects like ants can do crazy things like lift more than they weigh? This robot can do the same thing, lifting up to 100 times its own weight.

In the above video, you can see just how the little legs help move the caterpillar robot through the body. You also see how it transports a standard pill-sized object through an organ like the stomach.

The legs help it to move over liquid lined surfaces in the body. It can even maneuver whilst immersed in liquids such as mucus or blood.

image of motile or moving cilia for article Caterpillar Robot Developed to Improve Drug Delivery in Humans
Motile or moving cilia exhibit similar movements to the caterpillar robot’s legs | Amelia Shoemark

The little legs resemble things that naturally occur in the body like cilia.

These help move things such as eggs through an ovary or help to keep our windpipes clear. They can also be found in the ears, the eyes, the lungs, and many other places in the body.

By simulating these movements, the caterpillar robot maneuvers through the body.

But it wasn’t necessarily this biological feature that inspired the CityU researchers. In fact, the team studied leg structures of hundreds of animals from bipeds to quadrupeds and even creatures with eight or more legs.

But what mattered most what the ratio of the gap between legs and overall leg-length.

“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 the study leader Shen Yajing, Assistant Professor of CityU’s Department of Biomedical Engineering (BME).

As such, the robot had to have very specific dimensions if it was going to function properly.

image of the CityU research team that helped develop the robot for article Caterpillar Robot Developed to Improve Drug Delivery in Humans
Dr. Shen (front left), Professor Wang (front right), and CityU team members who developed the robot | CityU

What This Means for Medicine Moving Forward

The caterpillar robot, made of the silicon material polydimethylsiloxane (PDMS), is just .15 mm thick. Each of its conical legs measures around .65 mm long while its leg-gap is .6 mm. That makes the overall length-to-gap ratio 1:1.

Thanks to its reduced leg size, the robot has 40 times less friction than its limbless counterparts in both dry and wet environments.

Medical professionals can control the robot using a magnetic manipulator. They can move the robot in what’s called a “flap propulsion” pattern or an “inverted pendulum pattern”. This means that its front feet can flap the robot forward and swing the body left and right.

To increase the caterpillar robot’s speed, researchers can simply up the electromagnetic frequency.

Unfortunately, the robot, as yet, is not biodegradable. However, Shen indicated that the researchers plan to implement this feature in two or three years.

Perhaps this means that, in the future, medicine can work more effectively since it can reach the places in the body that it needs to affect more easily.

What other insects could science look to in order to improve medical technology and processes like drug delivery?

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