By Ashley Belanger
If you’ve ever swallowed the same round tablet in hopes of curing everything from stomach cramps to headaches, you already know that medicines aren’t always designed to treat precise pain points. While over-the-counter pills have cured many ailments for decades, biomedical researchers have only recently begun exploring ways to improve targeted drug delivery when treating more complicated medical conditions, like cardiovascular disease or cancer.
A promising innovation within this burgeoning area of biomedicine is the millirobot. These fingertip-sized robots are poised to become medicine’s future lifesavers – to crawl, spin, and swim to enter narrow spaces on their mission to investigate inner workings or dispense medicines.
Leading research in this field, Stanford University mechanical engineer Renee Zhao is working on many millirobot designs at once – including a magnetic crawling robot, which was recently seen worming its way through a stomach on the cover of Science Advances. Powered by magnetic fields – which allow for continuous motion and can be instantly applied to generate torque and change the way the robots move – her robots can self-select different locomotive states and overcome obstacles in the body. Just by shifting the strength and orientation of the magnetic field, Zhao’s team can send the robot sailing across the body at distances in a single leap that are 10 times the robot’s length.
A key aspect of her research, the magnetic actuation also provides untethered control for non-invasive operation and separates the control unit from the device to allow for miniaturization. Zhao said their most recent robot, featured June 14 in Nature Communications, is “the most robust and multifunctional untethered robot we have ever developed.”
This new “spinning-enabled wireless amphibious origami millirobot” is as multifunctional as its name implies. It’s an elegantly conceived single unit that’s able to speedily travel over an organ’s slick, uneven surfaces and swim through body fluids, propelling itself wirelessly while transporting liquid medicines. Unlike pills swallowed or liquids injected, this robot withholds medicine until “it reaches the target, and then releases a high-concentration drug,” said Zhao, who is an assistant professor of mechanical engineering. “That is how our robot achieves targeted drug delivery.”