Cats use special hairs on their faces to feel for unseen objects. A team of researchers has now developed electronic whiskers with a sensitivity and size mimicking their natural counterparts. The team coated flexible strands of silicon rubber with a mix of long chains of carbon atoms, called carbon nanotubes, and tiny bunches of silver molecules, called silver nanoparticles. The nanotubes added flexibility and durability while the nanoparticles added a way to measure small changes in strain on the whiskers. As each whisker flexes, the electrical resistance inside changes. By running a current through the whisker, the researchers measured the change in resistance and, therefore, the amount of flex.