Upconversion optical fiber microsphere sensor designed for precise measurement of FPGA temperature

In the realm of field-programmable gate array (FPGA) design, temperature emerges as a pivotal parameter that critically impacts system stability, reliability, energy efficiency, and fault diagnosis capabilities. Despite continuous advancements in temperature measurement technologies, real-time, rapid, and high-precision monitoring of FPGA surface temperature remains a central challenge in ensuring stable system operation, urgently requiring effective solutions. In this work, a fiber-optic temperature sensor for monitoring the surface temperature of an FPGA has been developed, featuring an upconversion luminescence-enhanced fiber microsphere structure consisting of upconversion nanoparticles (UCNPs) with polymethyl methacrylate (PMMA), ensuring high-precision temperature measurement capability. To investigate its sensing performance, the fiber-optic microsphere sensor was evaluated within the temperature range of 300-350 K using fluorescence intensity ratio (FIR) technology. The results revealed a peak relative sensitivity of 1.27% K^-1 at 300 K and demonstrated a detection accuracy superior to 0.5°C. The fiber-optic sensor was positioned on an FPGA chip and monitored for temperature changes through multiple consecutive power-on and cooling cycles. Comparison with the FPGA board's built-in temperature sensor showed high consistency in operating temperatures. Notably, the fiber-optic sensor demonstrated superior resistance to external environmental interference. The results indicate that the developed sensor, from material design to device application, has great potential for precise and stable temperature monitoring in FPGA applications.