Humidity adsorption kinetics of water soluble calix[4]arene derivatives measured using QCM technique

Abstract

a b s t r a c tWe report on the optimization and characterization of water soluble calix [4]arene derivative as a humidity sensor based on quartz crystal microbalance technique. The moisture adsorption and desorption kinetics of calix[4]arene were investigated. The Langmuir model was used to determine the kinetic parameters such as adsorption, desorption rates and Gibbs free energy between relative humidity between 29% and 78%. Reproducible experimental results were obtained showing that water soluble calix[4]arene films have a great potential for humidity sensing applications at room temperature operations.

Humidity Sensing Properties of Chitosan by Using Quartz Crystal Microbalance Method

“…The Langmuir analysis shows that the adsorption rate of chitosan layer with functional amine and hydroxyl groups in the molecular structure is at least 15 times faster compare to the adsorption rates of organic calix [4]arene 14 and organometallic Ruthenium 15 derivatives with carboxylate and sulphonate groups.…”

“…12 Ceramic sensors need an integrated heater to recover their humidity-sensitive characteristics, while polymeric sensors do not need a heating process, but they have been found to be less sensitive. 11 In recent years, the sensing properties of humidity sensors have been enhanced significantly 13 due to developing novel functional sensing elements such as organic calix [4]arene 14 and organometallic Ruthenium 15 derivatives with carboxylate and sulphonate groups.…”

Electrical Characterization of Interdigitated Humidity Sensors Based on CNT Modified Calixarene Molecules

“…In our previous paper, we reported on humidity sensing properties and adsorptiondesorption kinetics of calixarene based on QCM techniques [3]. The working principle * corresponding author of metal oxide or ceramic type of sensors is based on variation in electrical parameters such as resistance [10], impedance [11], and capacitance [1214].…”

New approach for consideration of adsorption/desorption data

“…QCM has been used frequently to measure the fractional coverage h as a function of time during the adsorption and desorption of water vapor molecules by Calix [4] arene films, while the increase in the frequency shift reflects the molecular mass uptake or loss [7,8]. Hence the difference between the oscillation frequency shift (D f) of coated and uncoated QCM is directly proportional to the adsorbed mass of moisture molecules.…”