The rapid advancements in microsystems technology have necessitated the exploration of innovative materials for efficient thermal management in micro heat exchangers. This research delves into the performance evaluation of three ultra-high temperature ceramics (UHTCs): ZrB2, BeO, and Si3N4 as alternative micro heat exchanger fabrication materials. The study systematically assessed the ceramics' interaction with Al2O3-nanofluids across diverse volume percentages and mass flow rates using the Taguchi optimization method. Beryllium oxide (BeO) emerged as the superior material, registering warm outlet temperatures as low as 64.86°C and cold outlet peaks at 31.68°C. Sensitivity analyses further underscored the critical role of inlet temperature on outlet dynamics, with warm and cold outlets showing significances of ~72% and ~99%, respectively. Additionally, the research pinpointed 0.75 vol% as the optimal Al2O3-nanofluid concentration, yielding the most favorable performance metrics across the ceramics.