Magnetic spray-on coating turns objects into magnetic robots

Researchers are working on all types of robots to allow them to climb through the human body to deliver drugs, among other things. This type of robot can be controlled with magnetic fields, and some can move through the colon and blood vessels. Researchers from City University of Hong Kong have developed a new spray-on coating that can give regular objects robotic capabilities.The team believes that the coating has significant potential for biomedical applications. Researchers have focused on using insect-scale robots measuring in millimeters with potential applications inside the human body. Rather than building the robot from the ground up, the researchers wanted to develop a tool that can be used to construct magnetic robots from ordinary objects. The tool came in the form of a spray known as M-spray.

M-spray is made of polyvinyl alcohol, gluten, and iron particles. It's able to adhere to smooth and textured surfaces on all kinds of materials. Lead researcher Dr. Shen Yajing said that the idea was that by putting the magnetic coat on objects, they could turn them into a robot to control its locomotion. M-spray can stick to the target object and activate the object when driven by a magnetic field.

The film formed by M-spray is less than 0.25 millimeters thick, which is key to maintaining the original object's form and size. In testing, the team could use their technique on cotton threads, thin films, and plastic pipes. The objects were turned into tiny robots capable of walking, crawling, and rolling with the help of a magnetic field.

Something interesting the team discovered during testing was that the mode of locomotion isn't set in stone when the coating is applied. The locomotion can be reprogrammed on demand by wetting the solidified coating, turning it into a glue-like material. The team can then apply a strong magnetic field, and the magnetic particles in the coating can be redistributed and realigned to change the way the robot reacts to the field.

The team has performed in vivo experiments using capsules coated with M-spray and anesthetized rabbits. The team could track the capsules as they move through the stomach with radiology imaging before dissolving the coating when the capsules reach the target location. The raw materials in M-spray can be absorbed or excreted by the human body.