A Highly Robust Ionotronic Fiber with Unprecedented Mechanomodulation of Ionic Conduction

TLDR

Stretchable ionic conductors are appealing for tissue‑like soft electronics, yet suffer from a tardy mechanoelectric response due to their poor modulation of ionic conduction arising from intrinsic homogeneous soft chain networks. The study designs a highly robust ionotronic fiber by synergizing ionic liquid and liquid crystal elastomer with alternating rigid mesogen units and soft chain spacers. This design yields an unprecedented strain‑induced ionic conductivity boost of about 103‑fold at 2000% strain. The fiber achieves this boost through strain‑induced microphase‑separated nanochannels and aligned smectic mesophases, enabling ultrafast ion transport that even reverses Pouillet’s law, supports waveform‑discernible strain sensing, retains 70% strain changes upon heating, and offers integrated self‑perception and actuation, highlighting a promising route for mechanically modulating ion transport in advanced ionotronic devices.

Abstract

Stretchable ionic conductors are appealing for tissue-like soft electronics, yet suffer from a tardy mechanoelectric response due to their poor modulation of ionic conduction arising from intrinsic homogeneous soft chain network. Here, a highly robust ionotronic fiber is designed by synergizing ionic liquid and liquid crystal elastomer with alternate rigid mesogen units and soft chain spacers, which shows an unprecedented strain-induced ionic conductivity boost (≈103 times enhanced as stretched to 2000% strain). Such a surprisingly high enhancement is attributed to the formation of microphase-separated low-tortuosity ion-conducting nanochannels guided by strain-induced emergence of aligned smectic mesophases, thus allowing for ultrafast ion transport that resembles the role of "swimming lanes." Intriguingly, the boosting conductivity even reverses Pouillet's Law-dictated resistance increase at certain strains, leading to unique waveform-discernible strain sensing. Moreover, the fiber retains thermal actuation properties with a maximum of 70% strain changes upon heating, and enables integrated self-perception and actuation. The findings offer a promising molecular engineering route to mechanically modulate the ion transport behavior of ionic conductors toward advanced ionotronic applications.