All-Electrospun Triboelectric Nanogenerator Incorporating Carbon-Black-Loaded Nanofiber Membranes for Self-Powered Wearable Sensors

Abstract

Triboelectric nanogenerators (TENGs) are capable of sustainably powering wearable sensors by harvesting diverse forms of ambient mechanical energy. Nevertheless, the material and structural designs of friction layers have significant impacts on the performance of TENGs. Electrospun nanofibers can enhance the electrical performance of wearable TENG because of their large specific surface area and porosity. Herein, the free-surface electrospinning technique was used to prepare the positive and negative friction layers with special structures of TENGs. The porous nanofiber membrane (NFM) of polylactic acid (PLA)/chitosan (CS)/aloin with good biocompatibility was used as the positive friction layer of TENGs. Furthermore, a certain amount of carbon black (CB) nanoparticles (NPs) were loaded into thermoplastic polyurethanes (TPU) to prepare beaded NFMs (BNFMs), which helped to improve the hydrophobicity and charge storage capability of the negative friction layer. The morphology of BNFMs with various CB contents and their electrical output performances as negative friction layers were compared, respectively. It was found that the BNFMs could deform under different pressures to enhance the contact area and electrical output of TENG. Moreover, the BNFMs loaded with CB can not only increase their surface roughness but also enhance the charge transfer rate and storage capacity of the friction layer. This provided TENG with good electrical output, high stability, and durability, as well as great application potential in harvesting various types of biomechanical energies. In addition, the proposed all-electrospun TENG had better flexibility, wearing comfort, and fabricating ease, which could be adhered to the human body for sensing human motion when embedded into textiles.

Emerging Trends of Nanofibrous Piezoelectric and Triboelectric Applications: Mechanisms, Electroactive Materials, and Designed Architectures

“…By adjusting the concentration parameters, bead‐on‐string “necklace”‐like structures can be prepared by electrospinning. [ 37,222–225 ] At lower concentrations, the polymer does not form viscous fibers, and the solvent does not evaporate effectively, resulting in large numbers of polymer spheres within the nanofibers. [ 37 ] This structure has been documented in several reports as a functional microstructure that can enhance the effective contact area with sensing materials, thereby improving the sensitivity and surface charge density of nanofiber devices.…”

PVDF piezoelectric sensor based on solution blow spinning fibers for structural stress/strain health monitoring

“…As we know, the self-polarization of PVDF can be achieved both by electric field forces and mechanical stretching forces, which can lead to all-trans (TTT) conformation of PVDF [11,35]. During the blow spinning process, the self-polarization of PVDF can be achieved by the tensile force of the air flow and the stretching effect of the drum rotation.…”

Nickel-Oxide-Doped Polyvinylidene Fluoride Nanofiber-Based Flexible Triboelectric Nanogenerator for Energy Harvesting and Healthcare Monitoring Applications

“…This high applied voltage during the electrospinning polarizes the dipole of PVDF. The spontaneous polarization further supports the electrical output of corresponding TENGs. − Electrospinning is the least expensive way to fabricate consistent and continuous micro- or nanofibers. , Owing to its advantageous properties including flexibility, light weight, breathability, higher specific surface area, huge accumulated surface charge density, and porosity, micro- or nanofibers hold great promise for creating a new triboelectric active layer. , Compared to conventional techniques, the electrospinning technique may easily alter the dipole moment of specific polymers by organizing them molecularly or modifying their crystal array to achieve higher electrical outputs. − Kim et al also found that the electrospun nanofibers tend to deliver enhanced power generation compared to casted films. The electrospun nanofiber’s network structure creates a greater surface area and higher roughness, which help to improve TENGs' electrical performance, whereas the casted film has a small and smoother uneven surface .…”