Harvesting ambient mechanical energy by multiple mode triboelectric nanogenerator with charge excitation for self-powered freight train monitoring

Railway freight transportation is an important way of land transportation. Due to the lack of on-board power supply of large number freight train carriages/containers, the power supply of electronic equipment for monitoring a train carriage is very difficult. Therefore, a self-powered real-time monitoring system is desperately necessary by in-site energy harvesting strategy. Herein, a multiple mode triboelectric nanogenerator (MM-TENG) assembled by multilayer floating sliding part and multilayer wave-shape contact-separation part is designed to collect the ambient mechanical energy on the freight train carriage joints to power the sensors for monitoring the train state. The multilayer floating sliding part effectively avoids the abrasion on the interface of tribolayers and easily harvests small trigger energy. The multilayer wave-shape contact-separation part is divided into several layer units, where only one-layer unit is used as a charge excitation TENG for the charge supplement to the whole TENG including multilayer floating sliding part and the rest of multilayer contact-separation part, which greatly improves the output performance of MM-TENG. The device parameters and test conditions are systematically investigated for optimizing output performance. The transferred charge of MM-TENG reaches 3.2 mu C by the normal triggering of linear motor at 2.5 Hz and a 470 mu F capacitor is charged to 5.2 V in 100 s. The lighting of 944 LEDs, the operation of temperate-humidity meter and the driving of a fire alarm after an energy management prove it as effective power supply for the sensors. This in-situ energy harvesting approach can be used in many fields for self-powered monitoring systems.