A nanogenerator for powering implantable biomedical devices could tap off the energy of a heart beat or the pulsing of blood vessels, according to Zhong Lin Wang and colleagues at the Georgia Institute of Technology, Atlanta. Writing in the journal Nano Letters Wang explains that pulse-powered nano-devices could be used in biosensing, environmental monitoring and personal electronics. His team has built a prototype nanogenerator consisting of zinc oxide nanowires, which can convert mechanical energy into electricity. The latest version of their device produces 20-30 times greater current than the original prototype and works even when immersed in biological fluids. The device "sets a solid foundation for self-powering implantable and wireless nanodevices and nanosystems in biofluid and any other type of liquid," the researchers say.