Masashi Kikuchi

Recognition of terpenes using molecular imprinted polymer coated quartz crystal microbalance in air phase

Abstract Quartz crystal microbalance (QCM) sensor which covered by molecular imprinted polymer (MIP) for terpene was fabricated. The MIP-QCM sensor was designed for enhance the sensor selectivity. The MIP membrane contained the methacrylic acid, which formed specific cavities originated by target molecule. The ingredients for MIP membrane was polymerized on the surface of QCM substrate.The sensing property was examined in gas phase for evaluate the sensor sensitivity and selectivity. The MIP-QCM sensor can detect terpene-contained gas. The sensor characteristics were strongly influenced by the composition ratio of cross-linker, functional monomer and template molecule. The response of the sensor towards terpene gases was partially reversible, however, the terpene gas partially remained in the MIP membrane. The remained molecule can be removed by immersing in a specific solution, and sensor can be used repeatedly. The sensor can distinguish the resemble gas successfully. Additionally, the newly fabricated MIP-QCM sensor showed particularly high sensitivity than that of conventional method.

Removal of toxic gas by hybrid chemical filter fabricated by the sequential adsorption of polymers

A high-performance chemical filter for toxic gas, such as ammonia or acetaldehyde, was newly fabricated by forming a layer-by-layer self-assembly film on the surface of a fiberglass cloth. The filter was greatly superior to the conventional active carbon filter. The newly developed filter showed remarkably high performance, because it can adsorb large amounts of gas molecules by both chemical and physical adsorption. Ammonia or acetaldehyde gases react with the polyelectrolytes in the film and are adsorbed into the multilayers of the films. In this paper, we report that the performance of the chemical filter is dependent on the nano-structure of the thin polymer film coated on the fiberglass cloth.

Quartz crystal microbalance (QCM) sensor for ammonia gas using clay/polyelectrolyte layer-by-layer self-assembly film

An ammonia gas sensor which has a high sensitivity in robust conditions has been investigated. A nanoporous thin film consisting of polyelectrolytes and sheet particulate /spl alpha/-ZrP was assembled by a layer-by-layer self assembly method on the electrode of a quartz crystal microbalance (QCM). This QCM sensor showed an eight times higher sensitivity than that of QCM deposited with /spl alpha/-ZrP by a casting method in low relative humidity. This means that the polyelectrolytes worked not only as a stabilizer to form a porous structure, but also as a material to keep moisture. Consequently, we considered that the gas sensitivity of the thin film is increased for other hydrophilic gases.

Thin polymer films for the filter of an air cleaner fabricated by mass-controlled layer-by-layer adsorption of polyelectrolytes

An extremely high performance of tobacco smoke filter for air cleaner was established by forming the polymer thin films on the surface of fiberglass by layer-by-layer sequential adsorption of polyelectrolytes. The mass controlled automatic dipping machine was used for the deposition process of the polyelectrolytes and it was easy to optimize the adsorption characteristics of the filter to smoke. The newly developed filter showed remarkably high performance because it adsorbed large amount of smoke without supplying electric power. It was also found that the polyelectrolytes filters can be cleaned just by rinsing in a hot water at 90u2009°C. Consequently, a remarkable high performance of the polymer filter for air cleaner can be produced by the mass-controlled layer-by-layer adsorption method of polyelectrolytes. Copyright

Ammonia sensors based on electrospun poly(acrylic acid) fibrous membranes

A novel gas sensor composed of electrospun nanofibrous membranes (FM) and quartz crystal microbalance (QCM) was successfully fabricated. The electrospun nanofibers can be deposited on the QCM electrode by electrospinning the homogenous blend solutions of cross-linkable poly(acrylic acid) (PAA) and poly(vinyl alcohol) (PVA). Moreover, the PAA fibrous membranes with different morphology can be deposited on the QCM electrode by electrospinning the PAA solutions with various solvent compositions of H/sub 2/O and ethanol. Sensing experiments were examined by measuring the resonance frequency shifts of QCM due to the additional mass loading. The results showed that the sensing properties were mainly affected by the content of the PAA component in nanofibrous membranes, the morphology of the fibrous membranes, the concentration of NH/sub 3/, and the relative humidity. Additionally, the sensitivity of the FM coated QCM (FM-QCM) sensor was much higher than that of a continuous film coated QCM (CF-QCM) sensor. Furthermore, the PAA FM-QCM sensors exhibited high sensitivity towards low concentrations of ammonia, as low as 130 ppb at the relative humidity of 40 %. The pre-sorbed water in the fibrous membranes was proved to be the key factor affecting the sensitivity of FM-QCM sensors for ammonia.