A mechanically soft-tissue-like organohydrogel with multi-functionalities for sensitive soft ionotronics

Abstract

To date, hydrogels with skin-like ionic conduction mechanisms are gaining popularity in fabricating soft electronics. Integrating the tissue-like mechanical properties and multi-functionalities into one hydrogel system is crucial for its practical application in diverse scenarios. Nevertheless, it remains a significant challenge to realize. Here, we present a mechanically soft tissue-like organohydrogel with ionic conduction mechanism and multiple functions via constructing plentiful “sacrificial bonds” (hydrogen bonding) between the hydrophobic association poly(acrylamide)/gelatin (HAPAM/gelatin) hydrogel and ethylene glycol/water (EG/H2O) clusters. By systematically optimizing the compositions, the organohydrogel displayed desired mechanical properties that fully matched human soft tissues, including the unique soft (∼77.8 kPa in Young’s modulus) yet tough (3.07 MJ m−3 in toughness) features. Meanwhile, the gel is tear-resistant (∼3.15 kJ m−2 in fracture energy), strong (∼0.4 MPa in tensile and ∼4.1 MPa in compression), and ultra-stretchable (∼1324 %). In addition, the organohydrogel integrated a broad spectrum of functionalities, including optically transparent, self-healing, freezing/heating tolerant, adhesive, and deformation sensitive. By taking these advantages, applications in soft ionotronic sensors for healthcare monitoring and information encryption/decryption were presented using the organohydrogel. It is expected that this work will shed some light on developing artificial materials with mechanical features resembling soft tissues and sophisticated functionalities.