Highly stretchable, flexible, and sensitive strain sensors have promising applications in motion detection—especially multifunctional strain sensors that can detect stretching, bending, compression and twisting. Herein, this study presents a graphene and glycerol solution-based multifunctional sensor with ultra-high stretchability and sensitivity. Owing to the self-lubrication and fluidity of the graphene-glycerol solution, the strain sensors display super stretchability up to 1000%, a maximum gauge factor up to 45.13, and excellent durability for over 10,000 cycles. In addition, the sensor can also rapidly respond to small strains (1%, 5%, 10%) and different stretching rates (12.5%/s, 25%/s, 50%/s, and 100%/s). More impressively, the sensors can measure up to 50 kPa pressure and 180° twisting without any damage. Furthermore, the strain sensors demonstrate their applicability in scenarios involving motion detection, such as that for finger bending, wrist rotating, touching, and drinking water.

The incorporation of a micro copper pillar is considered as the major interconnection method in three-dimensional (3D) integrated circuit (IC) intergradation under high-density I/O conditions. To achieve low-temperature bonding, this study investigated the thermosonic flip chip bonding of a copper pillar with a tin cap. The effect of bonding force on bonding strength was studied, and an average bonding strength 2500 g (approximately 84.8 MPa) was obtained in 2 s, at an optimized bonding force of 0.11 N per 40 μm pillar bump, and substrate temperature of 200 °C. Additionally, the effect of the bonding force on bonding interface microstructure and intermetallic compounds (IMCs) was also investigated. Tin whiskers were also observed at the bonding interface at low bonding forces.