<p>Hydrogel strain sensors represent an important development for research into flexible electronics, being able to convert external stimuli into easily monitored electrical signals. However, finding simple and rapid preparation methods, as well as ensuring compatibility between conductive fillers and the polymer matrix are still the main challenges for conductive hydrogel applications. In this work, we utilize MXene to coat liquid metal droplets that have been broken by ultrasound while incorporating cellulose nanofibers to make them stably dispersed. Electron paramagnetic resonance spectroscopy revealed that the obtained composite filler could catalyze the release of additional hydroxyl radicals from ammonium persulfate to enable the rapid gelation of acrylic acid under ambient conditions. This unique property allows for the mold-based fabrication of hydrogels in various shapes, and we also explored the use of microfluidic devices for printing. The conductive hydrogels showed good tensile properties, small hysteresis loops, high self-healing efficiency (97% conductive recovery), and antimicrobial properties. When assembled into flexible sensors, the hydrogel can accurately monitor body movements with stable repeatability. The outstanding characteristics of the hydrogel not only offer a material basis for the development of novel flexible sensors, but also have the potential for rapid, large-scale, and customized preparation through fast gelation.</p> Graphical abstract <p></p>