Gelatin and zinc ion-cooperated triple crosslinked hydrogels with high mechanical properties and ultrasensitivity for multimodal sensing and handwriting recognition

With the rapid development of flexible electronics technology, high-performance flexible sensors have shown great potential in wearable devices and human-computer interaction fields. In this study, a hydrogel (PMAGZ) reinforced by gelatin and Zn 2+ was prepared using a one-pot method, which formed a triple-bonded cross-linked network structure through covalent, hydrogen, and ligand bonds to exhibit excellent mechanical properties and sensing characteristics, and can be applied to multimodal sensors and handwriting recognition. The introduction of gelatin and Zn 2+ strengthens the cross-linked structure inside the hydrogel, which can effectively improve the tensile strength, strain, and toughness of the hydrogel. Additionally, the addition of ethylene glycol and lithium chloride endowed the hydrogel with good frost resistance and electrical conductivity. The PMAGZ hydrogel sensor has a fast response time, high sensitivity, wide sensing range, and excellent fatigue resistance, and is capable of accurately monitoring human movements and handwriting information. Combined with machine learning algorithms (ML), the sensor can effectively recognize different handwritten letters with an accuracy of 99.8 %. This study provides a new approach for developing high-performance, multifunctional flexible sensors, which have broad application prospects in flexible wearable devices and human-computer interaction fields.