Flexible 'fiber chip': integrating high-density integrated circuits into an elastic polymer fiber
Fiber electronics have evolved from passive conduits to active devices with sensing, powering, and display functions, yet their computational capabilities remain constrained by reliance on external rigid chips. This highlight reviews a recent breakthrough by Wang et al. that integrates high-density integrated circuits directly into elastic polymer fibers, achieving a multilayered spiral architecture with an unprecedented integration density of 100,000 transistors per centimeter. The fabrication process employs a highly flat polymer substrate with parylene encapsulation, a polydimethylsiloxane (PDMS) interlayer with modulus-gradient heterostructure, and adhesive interlayers with thickened edges to ensure mechanical robustness and uniformity. The resulting fiber-integrated circuits (FICs) demonstrate versatile computing functions, including digital logic gates (NOR, NAND, XOR, RS latches) and analog circuits (amplifiers, waveform generators). By incorporating organic electrochemical transistors (OECTs), the FICs achieve neural-style computing with 99.8% accuracy on the Olivetti Research Laboratory database. Notably, the FICs withstand 100,000 cycles of abrasion and 1-mm bending, indicating exceptional mechanical durability. This work addresses the critical bottleneck of integrating dense microdevice arrays into soft, cylindrical fibers, paving the way for truly intelligent and interactive fiber systems suitable for wearable and biomedical applications.