Hosup Jung

Novel array-type gas sensors using conducting polymers, and their performance for gas identification

Novel gas sensor devices have been developed using polythiophene (pTh) film and poly(3-n-dodecylthiophene) (pDpTh) film coated over pTh film. These polymer films were electrochemically deposited and doped by cyclic voltammetry on thin-film electrodes where the isolation gap was formed by a micromachining process. We examined the response characteristics of the conducting polymer films against various sample gases over a range of temperatures of the sensitive layer. The resistance changes of both sensitive layers of pTh and pDpTh were highly dependent on the kind of layer. In particular, pTh film responded to ammonia gas and pDpTh films clearly responded to hydrophobic gases, such as chloroform, methane and ethanol. The response of these films to several gases was analyzed with a pattern recognition (PARC) algorithm. It was found that our simple gas sensor device could discriminate between the gases that were used here.

Well-oriented nanowell array metrics for integrated digital nanobiosensors

Nanofabrication technologies should be useful for developing highly sensitive, reproducible nanobiosensors. This letter presents a nanometric system that is composed of well-oriented nanowells. The geometry permits only one or a few biomolecules to enter and become attached to nanosized gold dots. This nanoarray is easily fabricated using current nanolithography technology. When the authors applied this array to highly sensitive electrochemical DNA detection, they obtained a two-orders-of-magnitude enhancement in sensitivity. This nanometric system could be applied to numerous other integrated digital biosensors.

Highly dense protein layers confirmed by atomic force microscopy and quartz crystal microbalance.

Protein adsorption on a gold surface is investigated by comparing the results of quartz crystal microbalance method and atomic force microscopy. The adsorption of streptavidin on functional gold surfaces is directly monitored by a quartz crystal microbalance, and confirmed by atomic force microscopy. For this investigation, a modified gold substrate is fabricated to obtain a topographic image of streptavidin molecules. Both methods show a correlation in terms of the highly dense protein single-layer formation, and the modified gold electrode shows a slightly denser protein layer formation because of the difference in substrate geometry as compared with that of a mica surface.

Highly Sensitive and Selective Gas Sensors Using the Polythiophen Derivatives Controlled the Temperature

The advanced odor gas sensor devices were developed using the polythiophene derivatives. These polymers have been found to sense gases and vapours by monitoring the change in resistance on exposure of the polymer to the gas sample. These polymer films were electrochemically deposited and doped by cyclic voltammetry on thin-film electrodes where the isolation gap was formed by the micro-machining process. The breakthrough resulted in sensor devices with unique benefits, such as the very high selectivity and the operation possibility at ambient temperatures (steady and nonsteady state).