Highly aligned nickel fiber conductive structure for high sensitivity and low consumption in polymer-based strain sensors with negative resistance-strain effect

Conductive polymer composites (CPCs) have attracted considerable interest in strain sensing applications due to their excellent conductivity and high sensitivity. However, CPCs exhibiting a positive resistance-strain effect often suffer from high energy consumption owing to their low initial resistance, which limits their widespread application. Here, we present a novel CPC that exhibits high sensitivity and a negative resistance-strain effect, prepared using a liquid composite molding (LCM) method with highly aligned nickel nanofiber arrays (NFAs). A bilayer NFAs/polydimethylsiloxane (PDMS) composite structure was achieved through the infiltration of PDMS into the NFAs. Unlike CPCs produced by traditional blending methods, the 2D structure of the LCM-derived CPCs demonstrates a positive resistance-strain effect, while the resulting 3D structure displays a unique negative resistance-strain effect. Notably, these composites with a negative resistance-strain effect exhibit a strain-sensing sensitivity as high as 26,895. Furthermore, compared to most literature-reported sensors, our approach reduces energy consumption by three orders of magnitude. These findings offer a new perspective for the development of high-performance, low-power composites and broaden the application scope of strain sensors.Highlights Novel aligned Ni nanofiber arrays/PDMS composite fabricated via LCM. NFAs composites evolve from 2D to 3D networks with increased NF density. 2D and 3D networks show positive and negative resistance-strain, respectively. 3D network composites enable high sensitivity and low energy consumption.