Delineation of Parametric Controls on LTCC-Based Eddy Current Sensor Exposed to High Temperature

The investigation is focused on the parametric evaluation of a micro-fabricated Multi-Layer Planar (MLP) coil exposed to high temperature (≥ 600 °C). It can potentially be used as eddy current (EC) sensor for in-situ structural health monitoring (SHM) of critical engineering components. A detailed analysis of various contributing factors that affects the performance of the MLP coil is discussed. The coil is micro-fabricated on a ceramic substrate (DuPont L951 green tape) using state-of-the-art Low-Temperature Co-Fired-Ceramic (LTCC) technique. The stacked layer configuration (30 layers) soars the performance of the coil in terms of sensitivity and robustness. Emphasis is given on the performance both for dynamic & prolonged static thermal exposure. Delineation of electrical parameters particularly the series inductance (LS) of the sensor is found to be stable (~ 130 μH ±3%) up to 600 °C beyond which up to 800 °C, there is a decreasing trend (~ 70 μH ±3%). Also, the sensor shows stable and consistent behaviour with a nominal deviation of ± 1 % during prolonged thermal exposure. These findings throw light on the application of the MLP coil for in-situ SHM of critical engineering components exposed to high temperature.