Objective: Lumbar interbody fusion (LIF) is widely used to treat degenerative spinal disorders; however, both fixation strategies and interbody Cage designs still present biomechanical limitations. This study aimed to develop a posterior lumbar interbody fusion Cage using topology optimization and to compare the biomechanical performance of oblique pedicle screw fixation with conventional fixation. Methods: A validated three-dimensional nonlinear finite element model of the L1–L5 lumbar spine was established based on CT data. A two-step weighted topology optimization was applied to the L3–L4 interbody Cage to determine both the external contour and the internal bone graft window. Finite element models with oblique pedicle screw fixation and conventional pedicle screw–rod fixation were constructed and evaluated under static physiological loads and whole-body vibration conditions. Results: Compared with the conventional Cage, the topology-optimized Cage combined with oblique fixation significantly reduced the maximum von Mises stress on adjacent endplates and decreased Cage displacement under both static and dynamic loading. Although stresses in the Cage and screws increased relative to traditional fixation, all values remained well below material yield limits. Conclusions: The combination of a topology-optimized Cage and oblique pedicle screw fixation improves load transfer and structural stability while reducing the risk of endplate damage and Cage subsidence. This approach provides a promising alternative design strategy for posterior lumbar interbody fusion.

Transient temperature measurement under confined extreme thermal environments requires sensors with rapid response and structural stability. Conventional thermocouples often suffer from delayed response or insufficient junction protection, leading to inaccurate characterization of local thermal loads. In this work, a ceramic embedded junction thermocouple was developed for in situ transient temperature measurement. The sensor structure was optimized by finite element simulation, and a NiCr/NiSi junction was embedded into an Al₂O₃ ceramic substrate through inorganic bonding, thermal treatment, and surface grinding. The fabricated sensor was evaluated through thermoelectric characterization, high-temperature stability testing, dynamic response measurement, and calibration. The sensor exhibited a Seebeck coefficient of 41.26 μV/°C from 300 to 1200 °C, maintained continuous output at 1200 °C for 8 h, and achieved a response time of approximately 187 μs. The maximum relative deviation was below 0.47% within 300–1000 °C. During a confined thermal nose explosion test, the sensor successfully captured transient temperature evolution and recorded a peak temperature of approximately 1289 °C. Conventional thermocouples recorded peak temperatures below 800 °C, which were approximately 40% lower than the developed sensor. The proposed sensor provides a reliable approach for localized transient temperature measurement under confined extreme thermal environments.