Sungkyunkwan University team builds triboelectric DC generator with crest factor 1.143, battery-free IoT demo

A research team led by Professor Baek Jeong-min at the School of Advanced Materials Science and Engineering, Sungkyunkwan University, has developed a triboelectric direct-current generator (TDCG) and a battery-free Internet of Things (IoT) system built on it, kookminnews reported. The generator converts friction into direct current that can power electronics without a separate conversion circuit kookminnews.comkookminnewskookminnews.comOpen source ↗. The first author is doctoral student Kim Do-heon.

Why direct current matters

Triboelectric generators turn ordinary motion into electrical energy, like the static spark when clothes are removed in winter. Conventional devices produce alternating current with sharply fluctuating voltage and a constantly changing direction kookminnews.comkookminnewskookminnews.comOpen source ↗. Most electronics, such as smartphones and sensors, need steady direct current, so the signal passes through a rectifier, where much of the energy is lost kookminnews.comkookminnewskookminnews.comOpen source ↗.

Design, materials and test results

The team used the fact that charge generated by friction induces electrical polarization inside a special ceramic. The electrode structure was designed so that electrons flow in one direction only, following the friction signal. As a result, the crest factor, which describes voltage spikes, was lowered to 1.143, and the device produced steady direct current directly kookminnews.comkookminnewskookminnews.comOpen source ↗.

The authors also developed a composite of barium titanate ceramic particles and a functional polymer. According to the team, it holds more charge on the surface and reduces friction resistance and wear. The generator kept its performance through repeated friction cycles without wearing out and produced electricity stably for 25 hours at 99% humidity kookminnews.comkookminnewskookminnews.comOpen source ↗.

In a demonstration, door movement powered a self-powered multisensor IoT system that detects door opening, measures temperature and tracks location with a Bluetooth sensor kookminnews.comkookminnewskookminnews.comOpen source ↗. The authors say the approach suits smart logistics, cold-chain food transport and industrial facility inspections, where replacing batteries is difficult. Baek said the group will continue applied research toward wider deployment of battery-free sensor networks. The work was published in Energy & Environmental Science under the title "Triboelectric DC generation via dielectric polarization coupling for self-powered IoT systems" kookminnews.comkookminnewskookminnews.comOpen source ↗.