Cellulose Nanofiber-Reinforced Ionic Conductors for Multifunctional Sensors and Devices

Abstract

Ionic conductors are normally prepared from water-based materials in the solid form and feature a combination of intrinsic transparency and stretchability. The sensitivity toward humidity inevitably leads to dehydration or deliquescence issues, which will limit the long-term use of ionic conductors. Here, a novel ionic conductor based on natural bacterial cellulose (BC) and polymerizable deep eutectic solvents (PDESs) is developed for addressing the abovementioned drawbacks. The superstrong three-dimensional nanofiber network and strong interfacial interaction endow the BC−PDES ionic conductor with significantly enhanced mechanical properties (tensile strength of 8 × 10 5 Pa and compressive strength of 6.68 × 10 6 Pa). Furthermore, compared to deliquescent PDESs, BC−PDES composites showed obvious mechanical stability, which maintain good mechanical properties even when exposed to high humidity for 120 days. These materials were demonstrated to possess multiple sensitivity to external stimulus, such as strain, pressure, bend, and temperature. Thus, they can easily serve as supersensitive sensors to recognize physical activity of humans such as limb movements, throat vibrations, and handwriting. Moreover, the BC−PDES ionic conductors can be used in flexible, patterned electroluminescent devices. This work provides an efficient strategy for making cellulose-based sustainable and functional ionic conductors which have broad application in artificial flexible electronics and other products.

Multifunctional Liquid‐Free Ionic Conductive Elastomer Fabricated by Liquid Metal Induced Polymerization

“…[ 33,34 ] In our previous works, conductive elastomers with transparency and stretchability were developed based on cellulose reinforced acrylic acid (AA)/choline chloride (ChCl) type polymerizable deep eutectic solvent (PDES). [ 35,36 ] However, its self‐healing property was insufficient. Despite subsequent work improving this feature, water was introduced into the system simultaneously.…”

Recent Progress in Development of Wearable Pressure Sensors Derived from Biological Materials

“…Some biomaterials have complex inner hierarchical architecture, such as the fibrous structures of silkworm silk, [ 7c,66a ] spider silk, [ 74b,75 ] cotton, [ 15,99 ] bacterial cellulose, [ 100 ] animal collagen, [ 58 ] the tubular structures of poplar catkins, [ 23 ] the honeycomb and foam microstructures of wood, [ 101 ] and hollow structures of sunflower pollen. [ 102 ] These materials are attractive candidates for low‐cost and facile preparation of conductive structured biocarbon materials to fabricate highly‐sensitive wearable piezoresistive pressure sensors.…”

Recent Advances in Functional Bacterial Cellulose for Wearable Physical Sensing Applications

“…[50,51] Active materials like graphene oxide (GO) can be mixed with BC dispersion to fabricate nanostructured carbon aerogels through carbonization for sensing application [52] (Figure 3f). In situ polymerization is a strong interfacial interaction between active materials and BC; in situ polymerization of aniline and in situ photo-polymerization on BC were reported to construct multifunctional sensing materials [53,54] (Figure 3g,h). There are also other chemical modification methods to construct BC-based sensing materials, such as oxidation, hydrothermal synthesis (Figure 3i), and nitro functionalization.…”

“…Such as reduced graphene oxide (rGO)/BC carbon nanofiber aerogel, [52] polyvinyl alcohol/sodium alginate/BC/modified CNTs and carbon blacks (PVA/SA/BC/MCC) dual-cross-linked hydrogel [41] (Figure 4d), BC/ionic liquids/Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) nanocomposites, [63] and BC/polymerizable deep eutectic solvents ionic conductor. [54] In order to simplify the production process of BC-based piezoresistive sensing materials, Hosseini et al [39] fabricated a BC/rGO conductive aerogel using in situ biosynthesized method; the designed strain sensor presented a sensitivity of 19 (Figure 4e). Similarly, they [38] also added CNTs into BC culture medium solution during incubation process and a strain sensitivity of 21 and response time of 390 ms were obtained for BC/CNTs nanocomposite aerogel.…”