Polyelectrolyte elastomer-based ionotronic sensors with multi-mode sensing capabilities via multi-material 3D printing

Abstract

Stretchable ionotronics have drawn increasing attention during the past decade, enabling myriad applications in engineering and biomedicine. However, existing ionotronic sensors suffer from limited sensing capabilities due to simple device structures and poor stability due to the leakage of ingredients. In this study, we rationally design and fabricate a plethora of architected leakage-free ionotronic sensors with multi-mode sensing capabilities, using DLP-based 3D printing and a polyelectrolyte elastomer. We synthesize a photo-polymerizable ionic monomer for the polyelectrolyte elastomer, which is stretchable, transparent, ionically conductive, thermally stable, and leakage-resistant. The printed sensors possess robust interfaces and extraordinary long-term stability. The multi-material 3D printing allows high flexibility in structural design, enabling the sensing of tension, compression, shear, and torsion, with on-demand tailorable sensitivities through elaborate programming of device architectures. Furthermore, we fabricate integrated ionotronic sensors that can perceive different mechanical stimuli simultaneously without mutual signal interferences. We demonstrate a sensing kit consisting of four shear sensors and one compressive sensor, and connect it to a remote-control system that is programmed to wirelessly control the flight of a drone. Multi-material 3D printing of leakage-free polyelectrolyte elastomers paves new avenues for manufacturing stretchable ionotronics by resolving the deficiencies of stability and functionalities simultaneously.

Solid-state, liquid-free ion-conducting elastomers: rising-star platforms for flexible intelligent devices

“…Recently, the rational design of photopolymerizable 1-butyl-3-methylimidazolium 3-sulfopropyl acrylate and ethylene glycol methyl ether acrylate was harnessed as DLP-based 3D-printed ionic elastomers for manufacturing a variety of architected sensors. 129 Most interestingly, a photo-curable precursor of IL monomers containing 1-butyl-3-methylimidazolium 3-sulfopropyl acrylate was synthesized to achieve 3D printing of ionotronic sensors/devices with various architects and robust interface. 129 However, despite the tremendous achievement in exploiting customized 3D solid-state, liquid-free ion-conducting elastomers, they generally exhibit gentle degradation of performances such as stretchability, and Young's modulus, and self-healing ability compared with the elastomers prepared by bulk polymerization.…”

“…129 Most interestingly, a photo-curable precursor of IL monomers containing 1-butyl-3-methylimidazolium 3-sulfopropyl acrylate was synthesized to achieve 3D printing of ionotronic sensors/devices with various architects and robust interface. 129 However, despite the tremendous achievement in exploiting customized 3D solid-state, liquid-free ion-conducting elastomers, they generally exhibit gentle degradation of performances such as stretchability, and Young's modulus, and self-healing ability compared with the elastomers prepared by bulk polymerization. This is because the 3D printing process is performed within a relatively shorter time than conventional bulk polymerization, and thus leads to insufficient polymerization and cross-linking densities.…”

Ultrastretchable and Tough Poly(ionic liquid) Elastomer with Strain-Stiffening Ability Enabled by Strong/Weak Ionic Interactions

“…18,19 The ionconductive PILE based on 3D printing technology designed by Yang et al can be used as an iontronic sensor for multimode sensing, with extraordinary long-term stability and customizable sensitivity. 20 The polyampholyte elastomer developed by Choi et al exhibits excellent recovery ability and strong adhesion to the electrode by inducing strong ionic interactions between opposite charges in the polymer chain. 21 In addition, because the cations are immobilized in the polymer backbone and no liquid exists in the polymer network, PILEs can effectively solve the problems of water evaporation, freezing, and ionic liquid leakage.…”

High-Toughness and Intrinsically Self-Healing Cross-Linked Polyurea Elastomers with Dynamic Sextuple H-Bonds

“…Good tunable mechanical strength, outstanding toughness, and satisfactory elasticity are the most significant features of elastomers that permit their application in impact-resistant environments, , soft robots, − wearable electronics, − etc. More importantly, the crack-resistance, self-healing, environmental friendliness, reliability, and safety of the elastomers are demanded .…”