Abstract: Flexible sensors have attracted increasing attention, however most reported flexible sensors rely on single-signal detection. In this study, we successfully developed a multifunctional flexible sensor based on dual sensing mechanisms. A double-network hydrogel with a three-dimensional network structure was first prepared using polyvinyl alcohol (PVA) and chitosan (CS) through a two-step method combined with low-temperature freeze-thaw cycling. After modification with phosphoric acid/glycerol (H ₃PO ₄/GL), the hydrogel exhibited excellent comprehensive properties: a tensile strength of 2.91 MPa, an elongation at break of 294%, and only 2.5 cm of deformation after 1500 cyclic tests while maintaining stable stress. By comparing the self-healing properties of the PCG composite hydrogels under different environmental conditions, we found that the hydrogel demonstrated optimal recovery performance in an acidic environment. Subsequently, a dual-mechanism hydrogel-based flexible sensor is fabricated via low-temperature pressing. This sensor not only functions as a piezoresistive joint motion sensor for real-time monitoring of human activities (e.g., walking and running), but also generates stable triboelectric signals in humid environments for limb motion recognition. In addition, the sensor was applied for breath alcohol detection, where the resistance change rate exhibited a highly sensitive response to ethanol molecules. A linear fitting curve was established with a correlation coefficient of R ²= 0.99523, demonstrating excellent detection capability. This dual-modal sensing system effectively overcomes the limitations of traditional single-signal devices and provides a novel approach for the design of wearable electronics and sensing applications.