Reusable Cellulose‐Based Hydrogel Sticker Film Applied as Gate Dielectric in Paper Electrolyte‐Gated Transistors

Abstract

A new concept for reusable eco‐friendly hydrogel electrolytes based on cellulose is introduced. The reported electrolytes are designed and engineered through a simple, fast, low‐cost, and eco‐friendly dissolution method of microcrystalline cellulose at low temperature using an aqueous LiOH/urea solvent system. The cellulose solution is combined with carboxymethyl cellulose, followed by the regeneration and simultaneous ion incorporation. The produced free standing cellulose‐based electrolyte films exhibit interesting properties for application in flexible electrochemical devices, such as biosensors or electrolyte‐gated transistors (EGTs), because of their high specific capacitances (4–5 µF cm−2), transparency, and flexibility. Indium–gallium–zinc‐oxide EGTs on glass with laminated cellulose‐based hydrogel electrolytes (CHEs) as the gate dielectric are produced presenting a low working voltage (<2 V), showing an on–off current ratio (Ion/off) of 106, a subthreshold swing lower than 0.2 V dec−1, and saturation mobility (μSat) reaching 26 cm2 V−1 s−1. The flexible CHE‐gated transistors on paper are also demonstrated, which operate at switching frequencies up to 100 Hz. Combining the flexibility of the EGTs on paper with the reusability of the developed CHEs is a breakthrough toward biodegradable advanced functional materials allied with disposable/recyclable and low‐cost electronic devices.

Unconventional Inorganic‐Based Memristive Devices for Advanced Intelligent Systems

“…Mica substrate is another candidate for the flexible electronics due to its outstanding thermal stability up to 600 °C, while high manufacturing cost limits its applications . Recently, cellulose paper as flexible substrate is studied with the rise of single‐use disposable electronic devices that requires low cost and recyclable substrate . For the realization of flexible electronic system, the substrate materials should be adopted in consideration of the purpose and required characteristics such as mechanical stability, thermal stability, chemical resistance, optical transmittance, and recyclability.…”

Conductive Hydrogels as Smart Materials for Flexible Electronic Devices

“…In addition, hydrogel materials have remarkable biological characteristics (such as self‐healing, self‐adhesive, anti‐microbial activity and biocompatibility) to fulfill special demands . Therefore, in recent years, conductive hydrogels have been an active field of research flexible electronics present promising possibilities for flexible electrodes, flexible mechanical sensors, flexible displays and other devices with the human body . For example, flexible sensors can serve as the wearable health monitoring smart system for real‐time tracking of physiological signals in humans.…”

“…[27][28][29][30][31][32][33][34] Therefore, in recent years, conductive hy-drogelsh ave been an active field of research flexible electronics present promising possibilities for flexible electrodes, flexible mechanicals ensors, flexible displays and other devices with the human body. [35][36][37][38][39][40] For example, flexible sensors can serve as the wearable health monitoring smart system for realtime tracking of physiological signals in humans.F or the realization of the conductive-hydrogel-based flexible electronics, the most important consideration is the development of conductive hydrogel materials that support high carrier mobility and good overall electrical performance, together with mechanical and environmental stability.M aterials, including conductive polymers, metals nanoparticles/nanowires, carbonbased materials have been used and investigated as electrochemicala ctive materials for fabrication of various conductive hydrogels. [41][42][43][44][45][46][47][48] Recent works have reporteds ignificanta dvances in hydrogels with unique electronic and mechanicalp roperties.V arious strategies are availablet hat enable the mixture of electronicc onductive ingredients with hydrogel matrixes.…”

Recyclable High‐Performance Polymer Electrolyte Based on a Modified Methyl Cellulose–Lithium Trifluoromethanesulfonate Salt Composite for Sustainable Energy Systems

“…However, without substantial modification, their ion transport properties are rather mundane; hence, approaches such as hybridization or chemical functionalization are necessary to utilize them sufficiently. Nevertheless, these environmentally friendly, naturally abundant, and biodegradable polymers are still very attractive candidates for future energy‐storage devices, especially as concerns about the sustainability of energy systems are increasingly emphasized …”