Delivering chemotherapy drugs directly to cancers could help reduce side effects, and soon that job could be done by tiny 3D-printed robotic animals. These microrobots are steered by magnets, and only release their drug payload when they encounter the acidic environment around a tumor.

Scientists developed a new method of controlling certain nerve cells of the brain to manipulate behaviors - and it's delivered via viral injection. In 2016, researchers at the University of Virginia in Charlottesville genetically engineered a magnetized protein, called Magneto, which is inserted into a virus that's injected into an animal's brain to manipulate neural activity under the remote influence of magnetic fields.