A review on extrusion-based 3D-printed nanogenerators for energy harvesting

Energy harvesting technologies now play a significant role in the successful deployment of self-powered electronic devices. Researchers are working on small-scale energy generators fabricated with nanomaterials to harvest ambient energy. Triboelectric nanogenerator (TENG) is an efficient method for harvesting mechanical energy and powering battery-less tiny devices for wearable, implantable medical sensing and internet of things (IoT) sensing applications. So far, many fabrication technologies have been discussed in the literature for the fabrication of TENG including traditional micro/nano-fabrication technologies and 3D printing or additive manufacturing technologies. Extrusion-based 3D printing is a reliable approach for developing a fast, economical and controllable TENG device. This article provides a detailed analysis of recently used material combinations, design and structure formation, and output performance of extrusion-based 3D-printed triboelectric nanogenerators (EB-3DP-TENGs). Also, it presents their latest applications, including powering of electronic devices, silent speech recognition, voice print sensing and gait monitoring. Moreover, it discusses the crucial challenges and approaches used to enhance the performance efficiency of EB-3DP-TENGs. Finally, a visionary roadmap for the future development of EB-3DP-TENGs is provided, which will accelerate research and development.