The influences of SU8 sensor layer properties on sensitivity of capacitive chemical sensor were studied. It depends on differences in crosslinking of the sensor layer. The effect was obtained by hard baking after UV exposure. A combination of capacitive chemical sensors with optimised chemical structure with good discrimination between some volatile organic compounds (methanol, ethanol, isopropyl alcohol, butyl alkohol, acetone, hexsane, tetrachloroetene and toluene) was prepared.
COBISS.SI-ID: 4060442
Epoxy-based photoresist and conductive carbon black particles were used to prepare a conductive photoresist. Percolation threshold was achieved at 0,6 vol %. A large dependence of resistivity on the degree of crosslinking of polymer matrix was shown. Completely crosslinked polymer enables simple percolation conductive mechanisms also in circumstances where the distances between adjacent functional particles are too large for the conductive paths and nearest-neighbour tunnelling to be feasible.
COBISS.SI-ID: 4191002
Specific electrical resistivity of dry thin layers of composite has a typical percolation S-shape. It depends on state of dispersion of functional particles and on other preparation parameters. The state of dispersion is possible to modify by dispersing additives and by mixing. Degree of polymerization of the polymer matrix has a negligible effect on the state of particle dispersion, but it appreciably changes the dependence of resistivity on concentration of functional particles.
COBISS.SI-ID: 3889946
Three types of carbon black powders were analysed. They have very different average size and size distribution of aggregates, short-range order and surface chemical structure. Different amounts of graphitic, amorphous and disordered phases were detected. The analysed samples differ also in amount of oxygen and its bonding on powder surface. Oxygen was the only impurity detected on surfaces of all analysed powders.
COBISS.SI-ID: 22997031
The suitability of epoxy-based polymers for sensor layers in capacitive chemical sensors are discussed. The intrinsic material properties and the corresponding chemical structure are examined in particular.
COBISS.SI-ID: 5983572