Magnetoelastic Humidity Sensors with TiO₂ Nanotube Sensing Layers

In this study, TiO₂ nanotubes (TiO₂-NTs) are coated with a drop-casting method on Fe₄₀Ni₃₈Mo₄B₁₈ amorphous ferromagnetic ribbons and the humidity response of the prepared magnetoelastic sensors (MES) is investigated. The synthesis of TiO₂-NTs is performed using a hydrothermal process. Sample characterization is carried out using X-ray diffraction and scanning electron microscopy. The results show that the sensors can measure moisture values in the range of 5% to 95% with very high precision and very low hysteresis. The humidity variation between 5% and 95% shows a change in the sensor resonance frequency of ~3180 Hz, which is a significant change compared to many magnetoelastic humidity sensors developed so far.