Polymer films as sensitive coatings for quartz crystal microbalance sensors array

This work reports on the results of investigation of quarts crystal microbalance sensors coated with polybutyl methacrylate and polyvinyl formal/ethylal to wide range of volatile organic compounds. Polymer film coated sensors showed a high sensitivity and an excellent selectivity towards these compounds. Good linearity of the concentration dependence has been obtained in almost all the concentration range of volatile compounds. The detection limit of several analytes was less than 100 ppm

Study of the sensor response of spun metal phthalocyanine films to volatile organic vapors using surface plasmon resonance

tIn this work, thin films of chloroaluminium phthalocyanine (ClAlPc), fluoroaluminium phthalocyanine(FAlPc) and fluorochromium phthalocyanine (FCrPc), which are insoluble in conventional solvents, weredeposited by spin coating of their solutions in trifluoroacetic acid. The sensing response of these filmsversus acetic acid, three alcohols (methanol, ethanol, butanol) and three amines (methylamine, dimethy-lamine, trimethylamine) have been investigated using surface plasmon resonance as the sensing method.It has been shown that the sensor response of the investigated films decreases in the following order:acetic acid > alcohols > amines. The optical changes as monitored by SPR method have been used in con-junction with Fick’s second law of diffusion to determine the diffusion coefficients of analyte vapor duringthe films’ swelling process. The obtained results showed that the diffusion coefficients and the swellingcharacteristics of the films are dependent on the functional group of the phthalocyanine molecule andthe molecular size of the analyte

The role of shear modulus and viscosity of thin organic films on the adsorption response of QCM sensor

This work reports on the results of numerical calculations of quartz microbalance (QCM) sensors response under adsorption of analyte molecules. The influence of share modulus and viscosity has been studied. It was shown that even in the case of sufficiently thin films (hundreds of nanometers), the viscosity effects can significantly affect the sensor response during adsorption. In the case of sufficiently thick layers, the viscosity effects can turn out to radically change the response of QCM to the adsorption of volatile molecules. Thus, utilizing QCM-based sensors in viscous medium it is necessary to take into account not only mass loaded (adsorbed) onto quartz surface but also effect of viscosity on sensor response

Phosphorylated thiacalixarenes as molecular receptors for QCM sensors of volatile compounds

Sorption of volatile organic compounds and ammonia by thin solid films of phosphorylated thiacalixarenes was investigated by the quartz crystal microbalance (QCM), X-ray crystallography and molecular modeling methods The interfacial sorption depends on the number and position (upper or lower rim) of P=O groups on the macrocyclic skeleton, the electronic nature of the substituents at the phosphorus atom. At low concentrations of the analytes their sorption occurs according to the Langmuir isotherm due to specific supramolecular interactions with receptor centers of the thiacalixarenes. The analytes may form either the Host-Guest inclusion complexes stabilized by C-H...π interactions, or extracavity complexes stabilized by hydrogen bonds with oxygen atoms of the peripheral P=O groups. At high concentrations, when the thiacalixarene receptor centers are occupied by the analytes, further sorption occurs nonspecifically according to the linear Henry isotherm due to inclusion of the analytes in voids of the crystal structure of the thiacalixarenes