Researchers at Nanyang Technological University have built a millimeter-scale magnetic soft robot that performs five functions inside the body. Measuring 4.4 millimeters at its widest, it is steered wirelessly by weak magnetic fields, crawling or rolling through tissue before switching tools in under a second. A reprogrammable magnetic core lets it cut tissue, grip and store samples, dispense drugs, and heat tumors. In tests on gelatin and chicken liver, over 99 percent of exposed cells survived