Optogenetics, an approach in which cells engineered to express light-sensitive receptors are stimulated with a light source, has enabled important studies of neuronal activity. John Rogers, Robert Gereau and colleagues report the development of miniaturized devices made out of soft and stretchable materials and show they are fully implantable in mice. These tiny devices have an antenna that can receive radio power wirelessly and use it to activate LED lights, stimulating nearby neurons. They are also biocompatible and can interface with peripheral nerves and the spinal cord, which had previously been a challenge. The above image relates to the paper by Rogers, Gereau and colleagues, available now by clicking here.