Liquid-metal-elastomer foam for moldable multi-functional triboelectric energy harvesting and force sensing. (October 2019)

• Record Type: Journal Article
• Authors: Nayak, Suryakanta; Li, Yida; Tay, Willie; Zamburg, Evgeny; Singh, Devendra; Lee, Chengkuo; Koh, Soo Jin Adrian; Chia, Patrick; Thean, Aaron Voon-Yew
• Is Part Of: Nano energy. Volume 64(2019)
• Publication Date: 2019-10
• Subjects: Energy harvesting -- Porous TENGs -- Nanocomposites -- Liquid metal alloy -- Force sensing -- Wearable electronics; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2019.103912
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: This article reports on a moldable soft porous composite of liquid metal alloy (LMA) and Ecoflex-0030 elastomer for the first time, where random pores in the composite behaves as tiny triboelectric nanogenerators (TENGs). The triboelectric foam produced a maximum peak-to-peak short-circuit current (ISC ) of ~466 nA (charge density = ~35 μC/m 2 ) and open circuit voltage (VOC ) of ~78 V for a sample of size 5 cm × 5 cm × 1 cm, where the output current is ~20% higher than previously reported triboelectric foams based on PDMS and lead zirconate titanate (PZT)/carbon nanotube (CNT) of equivalent area. In addition, surface texture further increases the foam's softness and enhance the charge generation leading to a 36% increase in triboelectric charge (charge density = ~48 μC/m 2 ). A soft monolithic shoe insole is prepared, which produced a range of triboelectric responses in the order of μA in response to different modes of human motion. Upon jogging, the porous shoe insole with 3 wt parts of LMA in Ecoflex matrix, produce an instantaneous power of ~2.6 mW (instantaneous power density = 13 μW/cm 2 ). In addition, the insole also shows capacitive response to deformation, enabling the sensor to perform in-motion force and weight measurement. Graphical abstract: Image 1 Highlights: The triboelectric Ecoflex-Galinstan foam produced a maximum peak-to-peak short-circuit current (ISC ) of ~466 nA (charge density = ~35 μC/m 2 ) and open circuit voltage (VOC ) of ~78 V for a sample of size 5 cm × 5 cm × 1 cm subjected to 5 mm compression-relaxation cycles, where the output current is ~20% higher than previously reported triboelectric foams based on PDMS and PZT/CNT of equivalent area. The shoe insole produces an instantaneous power of 2.6 mW (power density = 13 μW/cm 2 ) in case of jogging, which can be used to power electrocardiogram (ECG) chips and other small-scale wearable sensors. There is change in capacitance with loading of different static or cyclic forces. So, this type of composites can be used as weight/force measurement sensor.