Tiny Robot Marks Step Toward Using Devices Inside Humans.
Scientists have developed a tiny robot that can walk, roll, jump, swim and even transport minuscule cargo, in step toward eventually putting robots to work inside the human body. The robot, a rectangular sheet approximately four millimetres long and one millimetre wide, is made of silicone rubber and embedded with magnetic particles. The researchers, who described their work on Wednesday, 24 January, in the journal Nature, manoeuvred the bot with an external magnetic control. The robot shortens and lengthens itself like an inchworm to walk and curls onto itself like a caterpillar to roll. Along with swimming, the robot can skim the surface of water much like a beetle larva. To pick up cargo, the robot curls over the object and grips it with both ends before rolling away to its target destination.
Researchers have been working on tiny soft robots for years with the hopes of one day using them in medical settings to deliver drugs to target tissues or to help with minimally invasive surgery. However, most of these robots have limited mobility and are unable to navigate effectively through more than one medium. This new robot is more adaptable, its creators say. “There are both solid and liquid environments in the human body,” said Metin Sitti, director of the Physical Intelligence Department at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany, and the paper’s senior author. “Our robot works with both.”
Dr Sitti and his team tested the robot in a synthetic silicone rubber stomach filled with water and found it was able to travel across both the synthetic tissue and fluid-filled parts. They also placed the robot inside a piece of chicken meat and found they could guide and visualise it using ultrasound imaging, which Dr Sitti said would be important for future medical applications. There are several limitations the robot needs to overcome before it can be used inside of a person. The magnetic particles inside the robot have the potential to cause an adverse immune reaction in human tissue, researchers said. Dr Sitti’s team hopes to develop a version that is both compatible with human tissue and biodegradable. “The challenge in this area is getting them to work in vivo, inside organisms,” said Bradley Nelson, professor of robotics and intelligent systems at Swiss technical university ETH Zurich, who also researches and develops small-scale soft robots and wasn’t involved in the project. “There are things to consider like biocompatibility and toxicity.” And at four-by-one-millimetres, the little robot is still much too large. Dr Sitti hopes to get the width down to less than eight micrometres, the approximate diameter of a human capillary. Dr Sitti says his team will next test the robot in animals, and clinical usage may be possible in seven or eight years.
Credit: Sarah Toy for The Wall Street Journal, 24 January 2018.