Papers by Author: Petr Saha

Abstract: Polyaniline thin films are chemically functionalized by nucleophilic addition of thiols beareing different functional groups: carboxylic, amine, -dodecyl and sulfonic. The modification is tested using FTIR and XPS spectroscopy. Then, the films are used as resistive sensors for different volatile organic compounds in a static measuring system. The sensitivity of conducting polymers to alcohols and heptane is strongly affected by the chemical functionalization of the materials. Polyaniline show an increasing signal when the chain length of different alcohols is increased. The incorporation of hydrophilic groups on the PANI chains seems to maintain the trend. On the other hand, the polymer modified with a long alkyl chain (PANI-DOT) show negative response for methanol and the signal increases up to propanol to decrease for longer chains. PANI-DOT show the largest signal for heptane of all polymers tested. Therefore, the functional group attached to the conductive polymer chain can be used to tune the molecular sensitivity of the resistive sensor

Abstract: Monitoring body kinematics and joint flexion has fundamental relevance in orthopedics and rehabilitation. The used sensing element is prepared from a highly-deformable polymer composite composed of a network of entangled electrically-conductive carbon nanotubes embedded in elastic polyurethane. The composite is prepared by an innovative procedure in which the non-woven polyurethane filtering membrane and the carbon nanotube cake are integrated by compression molding. As an example of the composite use as a strain sensor, human knee flexion and its cyclic movement is monitored, that may be applicable in athletic training as well as in orthopedics and rehabilitation.

Abstract: Multiwall carbon nanotubes (MWCNT) network “Buckypaper” was made by the vacuum filtration method of MWCNT aqueous suspension. The sensitivity of multi-wall carbon nanotube (MWCNT) networks of randomly entangled pure nanotubes to various organic solvent vapors (tetrahydrofuran, methyl ethyl ketone, and ethanol) has been investigated by resistance measurements. The results demonstrate that the network electrical resistance increases when exposed to organic solvent vapors, and a reversible reaction is observed when the sample is removed from the vapors. The investigated MWCNT networks could be potentially used as sensing elements for sensitive and selective organic vapor detection.

Abstract: Multiwall carbon nanotubes (MWCNT) network “Buckypaper” was made by the vacuum filtration method of MWCNT aqueous suspension. The sensitivity of multi-wall carbon nanotube (MWCNT) networks of randomly entangled pure nanotubes to various organic solvent vapors (tetrahydrofuran, methyl ethyl ketone, and ethanol) has been investigated by resistance measurements. The results demonstrate that the network electrical resistance increases when exposed to organic solvent vapors, and a reversible reaction is observed when the sample is removed from the vapors. The investigated MWCNT networks could be potentially used as sensing elements for sensitive and selective organic vapor detection.

Abstract: Two kinds of Multiwall carbon nanotubes (MWCNT) networks “Buckypaper” were made by the vacuum filtration method of MWCNT aqueous suspension. The first one was prepared from pure CNT and the second from its oxidized form by acidic KMnO4 as oxidizing agent. The CNT oxidation increase content of oxygen bonded to the surface of CNT decreasing their hydrophobic character. The sensitivity of MWCNT networks to two kind of organic solvent vapors (ethanol and hepane) has been investigated by resistance measurements. The solvents had different polarities given by Hansen solubility parameters and nearly the same volume fractions of saturated vapors at the condition of experiment. CNT oxidation significantly increases the sensitivity of CNT resistive sensor to vapors of ethanol and decrease response to heptane vapors. The present paper demonstrates the effective way how to add proper selectivity for organic vapor detection.