3D Printable, Highly Stretchable, Superior Stable Ionogels Based on Poly(ionic liquid) with Hyperbranched Polymers as Macro-cross-linkers for High-Performance Strain Sensors

Abstract

Stretchable ionogels have recently emerged as promising soft and safe ionic conductive materials for use in wearable and stretchable electrochemical devices. However, the complex preparation process and insufficient thermomechanical stability greatly limit the precise rapid fabrication and application of stretchable ionogels. Here, we report an in situ 3D printing method for fabricating high-performance single network chemical ionogels as advanced strain sensors. The ionogels consist of a special cross-linking network constructed by poly­(ionic liquid) and hyperbranched polymer (macro-cross-linkers) that exhibits high stretchability (>1000%), superior room-temperature ionic conductivity (up to 5.8 mS/cm), and excellent thermomechanical stability (−75 to 250 °C). The strain sensors based on ionogels have a low response time (200 ms), high sensitivity with temperature independence, long-term durability (2000 cycles), and excellent temperature tolerance (−60 to 250 °C) and can be used as human motion sensors. This work provides a new strategy to design highly stretchable and superior stable electronic devices.

Ionogel-based flexible stress and strain sensors

“…Tensile strain Stretchable and mechanical robust 3D printing Ionogel film or tube [49] Ionogel crosslinked network [50] Integrally-formed and encapsulated with elastomer [53] Solution cast…”

“…Human motion monitoring plays an important role in patient's motor function restoration. 3D printed tube-like IFSS can be put on human finger to detect its bending movements (Figure 8(a)) [49]. It also can be printed into simple stripe shape and fixed on different body parts, such as wrist and elbow, to detect their movements (Figure 8(b-c))) [49].…”

“…3D printed tube-like IFSS can be put on human finger to detect its bending movements (Figure 8(a)) [49]. It also can be printed into simple stripe shape and fixed on different body parts, such as wrist and elbow, to detect their movements (Figure 8(b-c))) [49]. Sensitive IFSS even can precisely monitor the bending angle of wrist, which is a promising application in evaluating patient's recovery situation (Figure 8(d)) [45].…”

“…Figure 8. The IFSS can monitoring human limb movements, such as (a) finger bending, (b) wrist flexing, (c) elbow bending[49] and (d) subtle wrist bending[45].…”

Spatially Controlled Highly Branched Vinylsilicones

“…The former approach is, therefore, more suitable for industrial scale-up [7]. In light of their unique properties, highly branched and hyperbranched polymers have been commercialized for applications ranging from coatings, additives, and insulators to biomedical applications [8][9][10][11][12].…”