Scientists have created the most non-stick surfaces yet, using microscopic liquid-repellent structures instead of plastic coatings such as Teflon. These new surfaces could help protect medical implants from gunk that can build up on and ruin the devices, endangering patients, researchers say. Natural materials such as insect wings and duck feathers are often water-repellent, or hydrophobic. Many other substances are oleophobic, which means they repel oil.