A team of scientists from Nanyang Technological University, Singapore (NTU Singapore) has built a tiny seed-sized robot capable of performing five surgical functions wirelessly, thereby paving the way for robots that make surgeries and medical treatments more precise.
According to its developers, the seed-sized robot, which measures just 4.4 mm in length, is controlled by weak magnetic fields and can travel to cut biological tissues, release drugs, grip and store tissue samples, or produce heat remotely at any one time. The team reports that it takes under one second to alternate between these functions.
Source: Nanyang Technological University
The team used magnetic coils in the lab to remotely control the robot so that it could deploy different tools and perform different functions — for instance, activating a tiny blade to cut through tissue, or emitting heat to a targeted area.
"Most magnetic robots like this can perform only one or two functions. Our latest invention can now do five, and our long-term goal is for doctors to use these mini robots in the body, navigate them to a targeted location, and use them to perform treatments," the team noted.
To incorporate several functions into one robot that is just a few millimeters long, the NTU team built a device for controlling movements that is triggered by magnetic fields and that can be reprogrammed in under just a second.
Composed of soft magnetic materials — including PDMS and Ecoflex — which are embedded with magnetic microparticles measuring 5 micrometers each, different parts of the robot are able to respond to magnetic fields.
Central to the design of the device is a magnetic module that can be magnetized, demagnetized and remagnetized in many directions. The team explained that each magnetic orientation triggers a different function of the robot, enabling the same mobile robot to perform five different functions — such as cutting and grasping tissues.
Different regions of a miniature magnetic robot were engineered so that only specific parts responded to the same magnetic field, thus enabling for the precise activation of tools and movements without impacting the entire device. This overcomes a limitation of small magnetic robots, which typically react as a single unit and are subsequently limited in maneuverability.
The new NTU-developed robot also introduces a sixth degree of freedom — rolling — which enables it to spin along its long axis for improved navigation through narrow, soft and irregular spaces within the body. Thanks to its solid yet flexible structure, this new robot is more durable and easier to retrieve.
During lab tests conducted on biological tissue models — including chicken liver and soft tissue simulants — the robot cut tissue, delivered drug-like particles collected samples and produced localized heat using magnetic fields, a technique associated with potential cancer therapies. Meanwhile, biocompatibility tests showed over 99% of human skin cells remained viable after exposure to the robot’s materials, which indicates low toxicity.
The technology is detailed in the article, “Miniature Soft Robot With Magnetically Reprogrammable Surgical Functions,” which appears in the journal Advanced Materials.
