No abstract

Aiming to improve the energy harvesting efficiency under low wind speed, we propose a dual auxiliary beam galloping triboelectric nanogenerator (GTENG) in this work. The structural design of a single main beam and a pair of auxiliary beams enables the device to work under a higher vibration frequency when triggered by wind. A stable and improved working frequency of about 4.6 Hz was observed at various wind speeds. The device started to vibrate at a wind speed of 1.7 m/s and generated an output voltage of about 100 V. The outputs of this GTENG approach to saturation at a wind speed of around 5 m/s. The output voltage and short-circuit current reached 260 V and 20 μA, respectively. A maximum power of about 1 mW was obtained under a wind speed of 5.7 m/s with a load of 33 MΩ. Moreover, the effectivity and long-term stability of the device were demonstrated under low wind speeds. A digital watch is powered for 45 s after charging a 47 μF capacitor for 120 s at a wind speed of 3.1 m/s.

Harvesting biomechanical energy for electricity as well as physiological monitoring is a major development trend for wearable devices. In this article, we report a wearable triboelectric nanogenerator (TENG) with a ground-coupled electrode. It has a considerable output performance for harvesting human biomechanical energy and can also be used as a human motion sensor. The reference electrode of this device achieves a lower potential by coupling with the ground to form a coupling capacitor. Such a design can significantly improve the TENG’s outputs. A maximum output voltage up to 946 V and a short-circuit current of 36.3 μA are achieved. The quantity of the charge that transfers during one step of an adult walking reaches 419.6 nC, while it is only 100.8 nC for the separate single-electrode-structured device. In addition, using the human body as a natural conductor to connect the reference electrode allows the device to drive the shoelaces with integrated LEDs. Finally, the wearable TENG is able to perform motion monitoring and sensing, such as human gait recognition, step count and movement speed calculation. These show great application prospects of the presented TENG device in wearable electronics.