Highly Aligned Cellulose/Polypyrrole Composite Nanofibers via Electrospinning and In Situ Polymerization for Anisotropic Flexible Strain Sensor

Abstract

Flexible strain sensors have recently attracted great attention due to their promising applications in human motion detection, healthcare monitoring, human–machine interfaces, and so forth. However, traditional uniaxial strain sensors can only detect strain in a single direction. Herein, an anisotropic flexible strain sensor is fabricated based on conductive and highly aligned cellulose composite nanofibers, via facile electrospinning cellulose acetate, deacetylation, and in situ polymerization of pyrrole, to detect complex multidimensional strains. Benefiting from the unique well-ordered structure of conductive composite nanofibers, the obtained strain sensor shows extraordinary anisotropic sensing performance with a sensitivity of 0.73 and 0.01 for the tensile applied perpendicular and parallel to the nanofiber alignment, respectively. The sensor also exhibits outstanding durability (2000 cycles) due to the strong hydrogen bonding between cellulose nanofibers and polypyrrole. Moreover, the flexible strain sensors exhibit promising potentials for application in motion detection, as demonstrated by the detection of various joint movements in the human body.

Review on Electrospun Conductive Polymer Composites Strain Sensors

“…Tunneling effect is one the most common application mechanisms for motion of electrons, which occurred on crossing the interparticles distance. [3,9,[51][52][53] There is a potential energy barrier between adjacent but not connected conductive fillers. Based on quantum mechanics, it is possible for electrons to move through the barriers between adjacent conductive fillers, which is the tunneling effect.…”

“…Meanwhile, this PEDOT:PSS-PVA nanofiber sensor presents good sensitivity with GF of 396. Li et al [3] reported an anisotropic cellulose/polypyrrole (PPr) flexible strain sensor via electrospinning cellulose acetate, deacetylation, and in situ polymerization of pyrrole (Figure 4e). The strain sensor shows good mechanical properties because of strong hydrogen bonding between cellulose and PPr, and investigates the effect of perpendicular to and parallel to the nanofiber structure on the sensor performance with sensitivities of 0.73 and 0.01, respectively.…”

“…Direct preparation by conductive spinning fluid: d) Direct fabrication process of aligned CNFs/PPr strain sensor with in situ polymerization. Reproduced with permission [3]. Copyright 2023, American Chemical Society.…”

Highly Stretchable, Ultra-Sensitive, and Self-Healable Multifunctional Flexible Conductive Hydrogel Sensor for Motion Detection and Information Transmission

“…This can solve the weak interface interaction between a rigid highly conductive filler and a flexible polymer matrix. Moreover, among many conductive polymers, polyaniline (PANI) and polypyrrole (PPy) are of low cost, easy to synthesize, stable in air, and with controlled physical properties. − Therefore, developing flexible multifunctional sensing materials utilizing conductive polymers such as PANI and PPy is of great interest to researchers. , …”

Capacitive properties of carbon nanofibers derived from blends of cellulose acetate and polyacrylonitrile

“…Thus, electrospun CA fibers are often transformed into stable cellulose via deacetylation in NaOH/ethanol solution. 37,38 However, the deacetylation process is corrosive and time consuming, resulting in cumbersome operations and increased costs. 39 In this study, PAN is replaced by CA to the maximum extent without losing excessive flexibility of the hybrid fibers.…”