Quartz Crystal Microbalance Odor Sensors Research Articles

Nanoassembled Thin-film-coated Quartz Crystal Microbalance Odor Sensors for Environmental and Human Breath Ammonia Assessments

Nanoassembled Thin-film-coated Quartz Crystal Microbalance Odor Sensors for Environmental and Human Breath Ammonia Assessments

水晶振動子式ニオイセンサシステムの機能設計と開発に関するレビュー

Functional design of organic polymer thin films as the molecular recognition membrane of quartz crystal microbalance (QCM)-type odor sensor system is reviewed. The organic polymer materials which are used as the molecular recognition membrane of QCM odor sensors are selected in the view of solubility parameters. It is found that the solubility parameter is very useful to choice the organic polymers as the molecular recognition membrane of the QCM gas sensors for target gas and odor. It is also found that the use of polymer films with nano-wires is effective to increase the sensitivity of the QCM odor sensors.

Highly sensitive QCM odor sensors with lipopolymeric nanocomposites and physisorbed amphiphilic GC materials

Purpose – This work has been motivated by the authors' long‐term research on odor‐sensing systems using acoustic wave‐based sensors and pattern recognition techniques. The sensors should be fabricated in such a way that they mimic performance of the olfactory receptors. In these terms, the purpose of this paper is to test a simple method for fabrication of quartz crystal microbalance (QCM) sensors by using nanocomposites and amphiphilic gas chromatography (GC) materials. The obtained sensors were intended to be highly sensitive to odorants at low concentrations and in high‐humidity conditions, as well as contributing to discrimination among odorant samples.

Linking biological and artificial olfaction: biomimetic quartz crystal microbalance odor sensors

AbstractBiological olfaction is a powerful system enabling acquisition and processing of various chemical information from environment. Vast significance of the sense of smell is reflected in attempts to create instrumental techniques mimicking the biological system—artificial/machine olfaction. Following the biological systems, the artificial olfaction relies on arrays of gas sensors with broad specificities to odorants. Arguably, among available gas‐sensing technologies, the most suitable choices for artificial olfaction are acoustic wave sensors, including quartz crystal microbalance (QCM) gas/odor sensors. The short review herein presents basic information on organization and principles of biological and artificial olfaction systems as well as several methods for fabrication of biomimetic or bioinspired (QCM) sensors for artificial olfaction. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Mixed self-assembled lipopolymers with spacer lipids enhancing sensitivity of lipid-derivative QCMs for odor sensors

Abstract An odor sensing system using a quartz crystal microbalance (QCM) sensor array and pattern recognition technique has been for years a main research topic in our group. For the general field of artificial olfaction using acoustic-wave based sensors such as QCMs it is vital to search for novel sensing materials. Here we present recent results of our ongoing study on application of pegylated lipids as coatings for QCM odor-sensors. The method presented herein is based on self-assembling of lipids and lipid-derivatives on the QCM surfaces. The disulphide-terminated lipids and lipopolymers are co-chemisorbed onto gold electrodes of QCM sensors by simple immersion in ethanolic solutions. This creates porous supports onto which additional layers of lipopolymers are physisorbed. The method allows for fabrication of lipopolymeric QCM odor-sensors with enhanced sensitivity to odorants, capable of very good discrimination among odorant samples—according to the functional group of an odorant.

Chemisorbed PEGylated lipopolymers as sensing film supports for QCM odor sensors

We report application of the PEGylated lipids (PEG lipopolymers) containing disulphide as supports for sensing films for quartz crystal microbalance (QCM) odor sensors. The materials are binding covalently to the surface of gold QCM sensor electrode creating self-assembled cushion. Additional amounts of lipid or lipid-derived materials can be physisorbed on that chemisorbed coating. Both processes do not require much labor and can be performed with minimum instruments in a simple process. The sensors fabricated with the chemisorbed supports are more sensitive to the tested odorants than their non-supported counterparts. Enhanced sensitivity is derived from higher fluidity of the supported films in comparison to the non-supported ones. Discrimination capability among odorants is also better for the sensors with chemisorbed supports than for the non-supported ones—there are no overlaps between the sample groups and the samples are clustered closely within the groups. Overall, the studied supported sensors introduce interesting properties that can be utilized in the odor sensing systems using QCM sensors.

Study of PEG Tether Length of Pegylated-Lipid Sensing Films in QCM Odor Sensors

Odor sensing system using quartz crystal microbalance (QCM) sensor array and pattern recognition technique has been for a long time an important research topic. Research of novel sensing materials for QCM odor sensors is vital for realization of artificial olfaction and related devices such as odor recorder. Herein we study quartz crystal microbalance (QCM, 20 MHz, AT-cut) sensors coated with lipopolymers with polyethylene glycol (PEG) as a tether. The tether's molecular weights were 1000, 2000 and 5000. In addition, we fabricated QCM sensors coated with PEGs of molecular weights 1000, 2000 and 4000. The fabricated sensors' properties were evaluated during experiments of exposures to vapors of alcohols, esters and acids. From the obtained results it is clear that the tether's length (molecular weight) is an important factor influencing the resulting material's sensing properties. Sensititivity patterns of the lipopolymeric sensors were clealrly different from the ones for respective polymers. The obtained sensors seem to have a good capability to discriminate among odor samples according to the functional group of an odorant.

Pegylated lipids as coatings for QCM odor-sensors

Lipids play an outstanding role in biological chemoreception schemes. The odorant–lipid interactions can be used as a mean of detecting the odorant molecules. A sensible way to exploit the interaction is coating the quartz crystal microbalance (QCM) sensors with natural or synthetic lipids or lipid-derived materials. Interesting candidates for such coatings are reported in the present paper—the synthetic lipids grafted with poly(ethylene glycol) (pegylated lipids, PEG lipopolymers). Two such materials grafted with PEG chains 2000 and 5000 were used for coating the QCMs. The obtained lipopolymer sensors were compared with pure lipid, pure polymer and lipid–polymer blend sensors. The results revealed very good discrimination power of the fabricated lipopolymer sensors for the range of odorants used in the study. The sensors have high sensor-to-sensor reproducibility and characteristics distinctly different from those for the remaining sensors used.