Porous polyvinyl alcohol/graphene oxide composite film for strain sensing and energy-storage applications

Abstract

In this study, a flexible porous polyvinyl alcohol (PVA)/graphene oxide (GO) composite film was developed and tested for flexible strain sensing and energy-storage applications. Morphology and mechanical properties were studied; tensile strength and Young’s modulus increased by 225% and 86.88%, respectively, at 0.5 wt% GO. The PVA/GO film possesses exceptional sensing ability to various mechanical strains, such as tension, compression, bending, and torsion. For example, the gauge factor of the PVA/GO film as a tensile-strain sensor was measured as 2.46 (246%). Under compression loads, the PVA/GO composite film showed piezoresistive and capacitive strain-sensing characteristics. Under 5 kPa of compression load, the relative resistance increased by 81% with a 100 msec response time; the relative capacitance increased by 160% with a 120 msec response time. The PVA/GO strain sensor exhibited high durability and reliability over 20 × 103 cycles of tensile strain and bending at 3.33 Hz. Moreover, the PVA/GO composite film showed good electrochemical properties due to its porous structure; the maximum capacitance was 124.7 F g−1 at 0.5 wt% GO. After 20 × 103 charging–discharging cycles, the capacitance retention rate was 94.45%, representing high stable capacitance performance. The results show that electrically conductive porous PVA nanocomposite films are promising candidates for strain sensing and energy-storage devices.

Key factors and performance criteria of wearable strain sensors based on polymer nanocomposites

“…Nanomaterials with excellent conductivity, such as CNTs [53], CB [54], graphene [55], and metal nanowires [40,56,57] are used for filler film fabrication. Moorthy et al [58] compared graphite and CB as filler materials for PDMS matrix-based strain sensors.…”

“…There are a plethora of studies on flexible strain sensors that have been published in the last decade; table 3 summarizes some parts of these studies, including the polymeric matrix, the conductive phase, and the measurments conducted to assess the developed sensor. It is evident that every element in the process of fabrication has a pivotal impact on a sensor's performance, such as filler content [55,59,60], chemical modification of the conductive phase [61][62][63], substrate type, synthesis process, etc. In the following sections, we will elucidate these factors in more detail as well as their effect on performance criteria.…”

“…A change in electrical resistance when force is applied to a sensor is called the piezoresistive effect. Conductive nanomaterials such as graphene [55,69], CNTs [93,94], AgNWs [95,96], and AuNWs [97,98] are examples of effective fillers used to endow strain sensitivity to polymers. In strain sensors, the GF is a measurement of the change in electrical signal when it is subjected to a mechanical strain.…”

“…In stretchable strain sensors, the GF value is diverse; it depends on the piezoresistivity, electrical conductivity, and geometry of the conductive filler, the matrix type, and the synthesis process. Wearable sensors with a high GF measure different angle deformations and normally have higher sensitivity [55,69].…”

Carbon Modification of K1.6Fe1.6Ti6.4O16 Nanoparticles to Optimize the Dielectric Properties of PTFE-Based Composites

“…This is mainly due to the properties of the polymer matrix, such as flexibility, chemical stability, and the ease and wide possibilities of molding products for various applications [ 1 , 2 , 3 ]. For example, they can be used as an insulating layer in an electric cable or as a film capacitor for energy storage [ 4 , 5 , 6 , 7 , 8 ]. However, polymer matrices have low values of permittivity, which limits their application in modern electronics [ 9 ].…”