Walking energy harvesting and self-powered tracking system based on triboelectric nanogenerators

Abstract

Due to the extensive energy consumption and high population density in modern cities, the collection and use of scattered walking energy from the stream of people is crucial for the development of a green ecological city. Herein, a flexible undulated electrode-based triboelectric nanogenerator (u-TENG) was integrated to the floor to scavenge walking energy from pedestrians, promoting the ordered collection of disordered and scattered energy. Driven by the steps of human walking, the output of the as-fabricated u-TENG are an open-circuit voltage of 86 V and a short-circuit current of 6.2 μA, which are able to continuously light up 110 light-emitting diode bulbs. In addition, a self-powered location-tracking system was prepared for pedestrian volume counting and passenger tracing with the purpose of reducing energy consumption in public areas. The proposed walking energy harvesting device is flexible, feasible, and unaffected by season, climate, or location. This work not only proposes a strategy for mechanical energy harvesting in public areas, including subway stations, hospitals, shopping malls, and business streets, but also offers a novel solution for smart cities and low-carbon transportation alternatives.

Keywords: harvesting walking energy; internet of things; mechanical energy; pedestrian flow area; self-powered tracking system; triboelectric nanogenerator.

Figure 1

A flexible undulated electrode-based triboelectric nanogenerator. (a) Schematic diagram of the fabricated u-TENG. (b) FESEM image of an inductively coupled plasma-etched PTFE film. (c) Representative picture of the as-prepared undulated electrode.

Figure 2

The working mechanism of the fabricated u-TENG in response to a stepping force. (a) The PTFE film and the undulated Cu electrode are brought into intimate contact by an external applied force. (b) When the force is released, free electrons flow from the Cu planar electrode to the undulated electrode. (c) The u-TENG reverts back to its unloaded position. (d) An external force compresses the u-TENG, driving the electrons move from the undulated electrode to the planar electrode.

Figure 3

Electrical measurement results of the u-TENG. Open-circuit voltage (a) and short-circuit current (b) of the prepared u-TENG at an impact frequency of 1 Hz. Open-circuit voltage (c) and short-circuit current (d) of the prepared u-TENG under different frequencies ranging from 1 to 5 Hz. (e) Dependence of the output voltage and current on the external loading resistance. (f) Plot of the power density as a function of the loading resistance; inset: long-term stability.

Figure 4

The ability of the u-TENG to harvesting energy from human walking. The electric output profile of a man (a), a woman (b), and a child (c). (d) The output voltage of u-TENG under different stress values. (e) The dependence of the output voltage on the impact force. (f) 110 LED bulbs are lit by stepping on a u-TENG.

Figure 5

Self-powered u-TENG-based location-tracking system. (a) Circuit diagram of the fabricated u-TENG-based tracking system. (b–d) Measured output voltage and real-time location mapping when the pedestrian arrives at the (b) first, (c) third, and (d) sixth electrode.