Optimization design of electrode configurations of lithium niobate tuning fork sensor

Due to its distinctive dual-cantilever structure and vibrational mode, the tuning fork (TF) sensor can simultaneously and decoupledly measure fluid density and viscosity. This has led to its extensive application in various industrial sectors, such as oil and gas exploration, petrochemical processing, food production, and textiles. The magnitude of the quality factor ( Q) is restricted by the effective electromechanical coupling coefficient. A higher coupling efficiency indicates more efficient energy conversion between electrical and mechanical domains, thus improving the Q value. This efficiency is influenced by multiple factors, including the design of the electrode configuration, layout, material properties, and geometric configuration. This study optimizes lithium niobate TF (LNTF) electrode configurations by integrating piezoelectric equations, thermoelastic effects, and contact models into an analysis framework to quantify electromechanical coupling, temperature coefficient of frequency (TCF), and Q value across configurations, with air experiments validating multiple mounting methods. The simulation results show that the double-sided electrode configuration 2 (a pair of positive and negative electrodes is patterned on one surface of each tuning fork arm, and the same electrode arrangement is symmetrically implemented on both the upper and lower surfaces) exhibits the highest excitation efficiency. Within 20–180 °C, the single-sided + suspended electrode configuration shows the smallest TCF (−73.01 ppm/°C) and better stability. Under elevated temperatures, double-sided electrode configuration 2 exhibits minimal Q value drift (6.06%), superior thermal stability, and suitability for fluid parameter measurement, supported by experimental validation of simulation findings. A comparative analysis of vibration characteristics under various electrode mounting methods in air and several standard oils verifies that the double-sided electrode configuration 2 exhibits excellent comprehensive performance, making it highly suitable for fluid sensor applications. This research provides theoretical bases and experimental evidence for the optimized electrode design of LNTF sensors.