Ionic Liquid/Water Binary Solvent Hydrogel for Flexible Strain Sensor

Abstract

Wearable electronics, particularly flexible strain sensors, have emerged as pivotal technologies for their capability to accurately detect mechanical deformations and convert them into measurable electrical signals, with promising applications in health monitoring and human-machine interfaces. However, hydrogels commonly used in these sensors are limited by their high-water content, which freezes at sub-zero temperatures, restricting their applications in extreme environments. This study addresses this limitation by developing an antifreeze, stretchable, and adhesive hydrogel using a binary solvent system composed of ionic liquid ([EMIM][BF₄]) and water, along with zwitterionic polymers and conductive PEDOT:PSS through a one-pot method. The introduction of ionic liquids significantly enhances antifreeze properties, mechanical flexibility, electrical conductivity, and adhesion. Comprehensive evaluations showed that the hydrogel exhibits robust mechanical stability, excellent conductivity, and reliable strain-sensing performance across a wide temperature range. Demonstrations on human joints further confirmed its potential for practical application in flexible, wearable sensors suitable for low-temperature environments.

Keywords

Hydrogel / Ionic liquid / Anti-freezing / Flexible strain sensor

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RIGHTS & PERMISSIONS

Jilin University, The Editorial Department of Chemical Research in Chinese Universities and Springer-Verlag GmbH