Hourglass Triboelectric Nanogenerator as a “Direct Current” Power Source

Hourglass, or sandglass, is known for centuries to record the passage of time. Here, an hourglass triboelectric nanogenerator (HG-TENG) is reported as a power source by harnessing the kinetic energy of falling particles. By employing the geometry of an hourglass and replacing the sand with a mixture of polytetrafluoroethylene (PTFE) pellets and Al balls, the HG-TENG delivers a train of electrical pulses of the same sign without a rectifier bridge. When the volume ratio of the PTFE pellets to the Al balls is 1:1, the HG-TENG is able to light up 160 commercial light emitting diodes intermittently for 18 s. Furthermore, it is demonstrated that the HG-TENG can also serve as a self-powered UV counterfeit detector.