Spatial Adjustment Strategy to Improve the Sensitivity of Ionogels for Flexible Sensors

Abstract

Recently, ionogels-based flexible/stretchable sensors have been receiving great attention, which greatly promotes the development of artificial flexible electronics. Except transparency, stretchability, stability, self-healing, and adhesion, the high conductivity of ionogels and high sensitivity as a sensor still are huge challenges. This work proposes a spatial adjustment strategy to improve sensitivity and conductivity through reducing the spatial hinderance without a change in the compound types and ratio. The addition of space pre-occupier during the preparation of the ionogel reduces the entanglement of polymer chains for better flowability of the polymer network. After removing the solvent from formed ionogels, the obtained free volume could facilitate the movement of ions and mobility of polymers. Through this way, the sensitivity (up to 1.6 times) and conductivity (up to 1.3 times) of ionogels are successfully improved, while maintaining their excellent transparency, stretchability, stability, and electromechanical properties, such as fast response speed and good repeatability. The detecting ability of movements of different parts of the human body is proved. It is worth mentioning that this simple and effective strategy needs no special requirement for chemical structure, so that it has broad applicability in various systems and opens up a new way for the development of flexible sensors.

Ultrastretchable Ionogel with Extreme Environmental Resilience through Controlled Hydration Interactions

“…As indicated in Figure S16 (Supporting Information), the experimentally derived relative resistance changes versus strain curve can be fitted into a quadratic function, exhibiting very similar trend to theoretical curve. Variations in the coefficients of fitted and theoretical functions are believed to be caused primarily by systematic differences, such as materials used, [53] cross-link density, [54] and even some measurement errors. These factors would impact the sensitivity of ionogels.…”

Bicontinuous Ionogel Electrolyte with Conductive Nanochannels for Flexible Supercapacitors

“…The mechanical properties of the bicontinuous ionogel and the reported ionogels are summarized in Figure f. It is found that the tensile strength, tensile strain, and toughness of the bicontinuous ionogel at the optimal formulation exceed those of most of the existing ionogels. − Most importantly, the bicontinuous ionogel obtains an excellent mechanical property without compromising its conductivity (discussed later).…”

“…Self-Healing and Recyclable Properties of the Bicontinuous Ionogel. Different from the covalent crosslinked ionogels, 25,40 the bicontinuous ionogel is synthesized without any chemical cross-linkers. The interpenetrated polymer-rich phase and solvent-rich phase are predominantly governed by hydrogen bonds.…”