Abstract
Detecting humidity have been remained a continuing concern within some important areas such as structural health, food processing, industrial as well as agricultural products. In this study, a novel humidity optical sensor is introduced based on the thermionic emission of tungsten filament using the fluorescent lamp set-up. Estimated blue compliant using a charged coupling device camera in optical image of the tungsten filament was confirmed as an appropriate detection system for relative humidity (RH) sensing. The fabricated optical sensor has wide linear range (2.0–98% RH), improved detection limit (< 5.0% RH), acceptable saturated limit (> 99.0% RH), improved percentage of relative standard deviation (4.18%, n = 2), adequate hysteresis (< 4.0% RH) and a shorter rise time (< 5.0 s), respectively. The mechanism behind this detection system is based on the interaction between H2O and tungsten filament during formation of W{mathrm{O}}_{3}.x {mathrm{H}}_{2}O (x = 1–2) in terms of some spectroscopic obtained evidences as well as Fourier transform infrared and X-ray diffraction spectrometries.
Highlights
Detecting humidity have been remained a continuing concern within some important areas such as structural health, food processing, industrial as well as agricultural products
Other tungsten based compounds such as tungsten(VI) oxide, modified with the molybdenum(VI) oxide has been selected for evaluation of the electrical and humidity sensing p roperties[18]. About most of these gas sensing devices, in spite of their capability such as their moderated selectivity for gas sensing p urposes[16,17,18], but they often suffer from problems such as small sensitivity, high hysteresis, fatigue and or lack of reusability. To solve these problems, it has been focused on the nanotechnology such as W nanowires[19], but, regardless of noticeable advantages of chemical reaction based-sensors, they are influenced by some drawbacks such as small water permeability, irreversible water adsorption/absorption resulting in significant memory effects, besides the inadequate hysteresis), and low selectivity against H 2O compared to other organic/inorganic species, especially volatile organic compounds[22,23]
Humidity sensor was constructed based on chemical reaction between water vapor and tungsten filament
Summary
Detecting humidity have been remained a continuing concern within some important areas such as structural health, food processing, industrial as well as agricultural products. Chemical reaction based-sensors comprise of a transducer and an active layer to convert the chemical information into another form of electrical signal gradients like frequency, current, voltage, etc.[6,7,8] Their performance characteristic is often based on some different figures of merit including sensitivity, selectivity, detection limit, response time, recovery time, and so on). Other tungsten based compounds such as tungsten(VI) oxide, modified with the molybdenum(VI) oxide has been selected for evaluation of the electrical and humidity sensing p roperties[18] About most of these gas sensing devices, in spite of their capability such as their moderated selectivity for gas sensing p urposes[16,17,18], but they often suffer from problems such as small sensitivity, high hysteresis, fatigue and or lack of reusability. Instrumentation system (gun) with significant advantages such as low cost, availability and/or almost simple detection systems
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