Highly flexible and conductive stainless-steel thread based piezoelectric coaxial yarn nanogenerators via solution coating and touch-spun nanofibers coating methods

Abstract

The concept of nanogenerators (NGs) based on textiles was introduced to impart functional attributes to textiles for developing smart textiles and integrating wearable electronics of various functionalities. The human body can generate sufficient mechanical energy that can be harvested by the piezoelectric nanogenerators (PENGs) and used to power up low power consuming wearable electronics. Two simple and easy approaches for coating a highly conductive weave-able metal electrode with polyvinylidene fluoride (PVDF) piezoelectric polymer to construct two different types of coaxial yarn-based PENGs are presented in this paper (Y-PENGs). The proposed techniques result in the in-situ formation of the β phase of the PVDF. The Y-PENGs are based on facile solution coating and touchspun nanofibers (TSNFs) coating of the inner electrode. The solution-coated Y-PENG (SC-YPENG) shows 5.12 V of peak open-circuit voltage (Voc) and 41.25 nA of peak short circuit current (Isc ). Whereas the TSNFs coated Y-PENG (NFC-YPENG) shows 5.08 V of peak Voc and 29.1 nA of peak Isc. In a series connection, the average peak Voc synergizes by ⁓2.53 and ⁓2.4 factor respectively for the SC-YPENG and the NFC-YPENG. The Y-PENGs can store charge into a capacitor and run LEDs. Additionally, our coated inner electrode shows great flexibility, thereby it could be knitted or woven into smart textiles to run wearable electronics sustainably.

Parasitic capacitance modeling and measurements of conductive yarns for e-textile devices

“…As a case study that incorporates the estimated parasitic capacitances of conductive yarns, we will calibrate the resonante frequency of embroidered NFC coils that are commonly used in smart apparel applications. Yarn-based NFC devices are getting increasingly popular in wearable electroncs in recent years as they benefit from the flexibility and breathability 30 , 31 of the fabric-based structures. Traditional inductance calculation method for NFC coils uses Wheeler’s equation, which is based on the assumption of metallic conductors.…”

Recent advances in piezoelectric textile materials: A brief literature review

“…The advancement of technology and the need to develop more sustainable materials that are not dependent on limited energy resources and the miniaturization of devices to offer comfort to the user, piezoelectric textiles produced from polymers have stood out. In recent years, numerous researches have been carried out on piezoelectric textiles in the most diverse areas, especially material sciences, engineering, physics, astronomy, chemistry, and energy, as shown in Figure 2, 78 for example, developed piezoelectric nanogenerators from coaxial wires of PVDF and flexible stainless steel. The main objective was to develop from two different techniques for coating the metallic electrode, by solution and torque spinning, a piezoelectric textile capable of generating an electric field.…”

“…The main objective was to develop from two different techniques for coating the metallic electrode, by solution and torque spinning, a piezoelectric textile capable of generating an electric field. 78 Jun Sim 79 and Peng et al 80 invested in flexible nanogenerators from PVDF piezoelectric wires and silver-coated nylon fibers using techniques such as electrospinning to obtain nanofibers and nanowires with differentiated properties such as softness, flexibility, and constant piezoelectric voltage, with potential application as wearable sensors.…”

Hybrid Piezoelectric/Triboelectric Wearable Nanogenerator Based on Stretchable PVDF–PDMS Composite Films

“…5,6 Piezoelectric nanogenerators (PENGs) are not only able to collect mechanical energies from the environment and convert them into electric energy by piezoelectric materials but also have high sensitivity to detect kinetic energies associated with human movements, such as heartbeat, pulse, muscle contraction, and breathing. 7,8 Polyvinylidene fluoride (PVDF) is the most intensively investigated piezoelectric polymer given its low density, high flexibility, low electrical resistance, and high piezoelectric coefficient. 9−11 PVDF has several crystalline polymorphs (α, β, γ, δ, and ε) depending on the chain conformation, among which the β phase is of the highest importance in energy harvesting applications because of its spontaneous polarization and piezoelectric sensitivity.…”

“…Piezoelectric nanogenerators (PENGs) are not only able to collect mechanical energies from the environment and convert them into electric energy by piezoelectric materials but also have high sensitivity to detect kinetic energies associated with human movements, such as heartbeat, pulse, muscle contraction, and breathing. , Polyvinylidene fluoride (PVDF) is the most intensively investigated piezoelectric polymer given its low density, high flexibility, low electrical resistance, and high piezoelectric coefficient. − PVDF has several crystalline polymorphs (α, β, γ, δ, and ε) depending on the chain conformation, among which the β phase is of the highest importance in energy harvesting applications because of its spontaneous polarization and piezoelectric sensitivity. Among various approaches in inducing the β phase in PVDF, electrospinning, which fabricates the β phase nanofiber membrane without additional mechanical stretching and electric poling, has been regarded as the simplest and most efficient technique in realizing piezoelectric PVDF structures. , In spite of their superior pressure sensing sensitivity resulting from super softness and the highly porous structure, piezoelectric PVDF nanofiber membranes still suffer from low electrical outputs and poor mechanical stability. , …”