Self‐Sintering Ionogel Binder for Flexible, Recyclable, and Healable Printed Giant Magnetoresistive Sensors

ABSTRACT Electronic waste has emerged as a major environmental challenge, driven by the massive consumption and a limited lifetime of modern electronic devices, stimulating the development of sustainable electronics. Here, an all‐biomaterial gelatin‐choline‐citric acid ([Ch][CA]) ionogel is developed as an active binder to realize self‐sintered, healable, and recyclable printed giant magnetoresistance (GMR) sensors using [Co/Cu] 50 microflakes as functional fillers. By tuning the choline‐to‐citric‐acid ratio, excess protons are released during drying, etching oxide passivation layers on the flakes and driving in situ self‐sintering. The printed sensors possess magnetoresistance ratio of 7.1% at 300 mT and maintain stable performance under bending down to a 0.4 mm radius. The reversible sol‐gel transition of the gelatin‐[Ch][CA] binder matrix imparts healing capability upon mild heating and full recyclability via dissolution and magnetic recovery of fillers. The ionogel provides excellent mechanical flexibility enabling integration in smart wearables. This demonstration of self‐sintering, healable, and recyclable printed GMR sensors based entirely on biomaterial‐based binders offers a sustainable route toward next‐generation flexible magnetoelectronics.