Humidity sensing and breath analyzing applications of TiO2 slanted nanorod arrays

Abstract

Humidity sensing devices are fabricated using titanium dioxide nanorod arrays and studied in this work. TiO2 slanted nanorods were grown by using electron beam assisted physical evaporation technique by keeping quartz substrates at a glancing angle of 80°. TiO2 slanted nanorod arrays were characterized using XRD, FESEM with EDS, HR-TEM, and Raman spectroscopy techniques. XRD characterization reveals that as-deposited nanorods are amorphous, and annealing at 500 ℃ for 6 h leads to anatase crystal structure. FESEM confirms the growth of uniformly distributed nanorods without any cracks throughout the substrate. Further, the humidity sensing property was analyzed for both as-deposited and annealed samples with bottom gap electrode configuration. The sensing towards a wide humidity range was tested for fabricated TiO2 devices of both as-deposited and annealed TiO2 nanorods in a homemade humidity sensing setup. Remarkably, the annealed TiO2 nanorod sensor is found to be having high sensitivity and fast response and recovery times of 145 and 210 ms, respectively, for 95 % humidity. Finally, to check the practical applicability, the TiO2 nanorod sensors were used to analyze the humidity level in exhaled human breath to determine the dehydration level.