Stretchable Multifunctional Polydimethylsiloxane Composites with Cage‐Like Conductive Architecture for Integrated Thermosensitive and Electromagnetic Interference Shielding Performance

Abstract

High‐performance sensors with outstanding sensitivity, wide working range, and multifunctional properties are highly desirable in modern integrated smart wearable electronics. Herein, polydimethylsiloxane (PDMS)‐based stretchable pyroresistive sensors composed of tightly‐assembled silver nanowires (Ag NWs)‐encapsulated PDMS microspheres (PM) and expandable microspheres (EM) are fabricated. The synergistic cage‐like conductive network and EM endow the temperature sensor with tunable sensitivity (Max TCR: 27.4% °C−1), broad sensing range (25–85 °C), low perception limit (0.1 °C), and excellent anti‐interference ability. Interestingly, at elevated temperature field (> 90 °C), a remarkable conduction‐insulation transition is observed, which is employed to facilitate an early fire alarm system. In addition, the selectively distributed Ag NWs constructs segregated conductive pathways at an ultralow content (Pc = 0.014 vol%), leading to efficient electromagnetic interference shielding (40.0 dB). The underlying mechanism responsible for the observed superior thermosensation and EMI shielding performance is elucidated, and possible applications are demonstrated. Consequently, this work offers a novel strategy for the design of flexible, multifunctional pyroresistive sensors toward artificial intelligence and emerging wearable electronics.

Spongy Ag Foam for Soft and Stretchable Strain Gauges

“…Strain gauges that are soft and stretchable are of particular interest in wearable sensing applications, such as human motion monitoring and human–robot interaction, owing to their ability to effectively accommodate external strains of up to 50% or more on the skin. − Most of these strain gauges are usually constructed using elastomers that contain various forms of conductive nanomaterials, such as particles, − tubes, − wires, − films, − flakes, , and shells, , which cause a shift in resistance when stretched. The shift is originated from the disconnection and reconstruction of electrical network formed by the conductive materials, and the modification of types, size, and concentration of the conductive materials facilitates the fine-tuning of performance in stretchable devices. − For reliable sensing, these strain gauges require a high degree of stretchability, softness, sensitivity, selectivity, and linearity, while avoiding mechanical and electrical hysteresis, overshoot behavior, and slow response/recovery time. , Efforts to enhance sensor performance have been pursued through considerations of various aspects, including the combination of materials, microstructural modifications, and interfacial stability between elastomers and conductive materials. − Despite significant advances, satisfying all of these essential features without any trade-offs continues to be a challenge.…”