Liquid Metal Bridges Stabilize Graphene Conductive Networks in Porous Thermoplastic Polyurethane for Broad-Range and Durable Piezoresistive Sensing

Flexible porous piezoresistive materials are promising for wearable pressure sensors because of their low modulus, high compressibility, and structural adaptability. Their practical performance, however, is constrained by a trade-off among sensitivity, operating range, and cycling durability. This trade-off is particularly acute in conductive networks near the percolation threshold, where large pressure-induced resistance changes are accompanied by contact instability during repeated deformation. Here, we fabricate a three-dimensional interconnected thermoplastic polyurethane/graphene/liquid metal (TPU/G/LM) porous composite by freeze-drying. Graphene forms the primary piezoresistive network, whereas LM serves as a deformable electrical bridge between neighboring graphene domains, thereby promoting reversible pathway reconstruction and stabilizing electrical contacts during compression. At 14 vol% LM, the sensor operates from 11.1 Pa to 300 kPa, reaches a sensitivity of 4.46 kPa-1 in the low-pressure regime, exhibits response and recovery times of approximately 1 and 4 ms, respectively, and maintains a stable response over 20,000 cycles at 100 kPa. Demonstrations of wearable motion monitoring and wireless thermal warning further illustrate the potential of LM-bridged graphene networks for broad-range, durable, and multifunctional sensing.