Oxidized Carbon Nanohorns/KCl/ PVP Nanohybrid as Sensing Layer for Chemiresistive Humidity Sensor

This paper reports on the relative humidity (RH) sensing response of a resistive sensor employing sensing layers based on a ternary nanohybrid comprising oxidized carbon nanohorns (CNHox), KCl and polyvinylpyrrolidone (PVP), at 3/1/1 w/w/w ratio. The sensing device includes a silicon substrate, a SiO
2
layer, and interdigital transducer (IDT)-like electrodes. The sensing film is deposited via the drop-casting method on the sensing structure. The sensing layer’s morphology and composition are investigated through Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and RAMAN spectroscopy. The resistance of the proposed detection structure is shown to steadily increase when exposed to RH ranging from 0 to 100%. The sensor has a response comparable to that of a commercially available, state-of-the-art, capacitive RH sensor. The RH sensitivity of the proposed sensing layer is thoroughly explained by several theories, including the Hard-Soft Acid-Base (HSAB) theory.