https://doi.org/10.15407/iopt.2019.54.088
Optoelectron. Semicond. Tech. 54, 88-95 (2019)
H.V. Dorozinska, G.V. Dorozinsky, V.P. Maslov, K.P. Grycenko, Yu.V. Kolomzarov, P.M. Lytvyn, T.P. Doroshenko
FEATURES OF APPLICATION OF THE ADDITIONAL NANO LAYER OF POLYTETRAFLUOROETHYLENE IN SENSORS BASED
ON SURFACE PLASMON RESONANCE PHENOMENON
It has been experimentally proved that the use of an additional polytetrafluoroethylene nano layer (PTFE) of 30 and 40 nm thickness on the gold surface of a SPR sensor provides an amplification of response to saturated vapors of methanol, ethanol, acetone and isopropanol by increasing the surface area of the interaction. In the presented work, SPR sensors with an additional layer of PTFE in thicknesses of 5, 10, 20, 30, 40 and 50 nm were investigated. Feedback amplification is consistent with an increase in the area of the surface of the sensitive sensor element with a correlation coefficient of 0.88. The surface roughness first grows due to an increase in its heterogeneity (for PTFE layers with thickness from 5 to 40 nm inclusive), and then falls due to the formation of a more homogeneous PTFE layer (for a thickness of PTFE layer of 50 nm). For a sensitive element with a thickness of PTFE of 20 nm, sensitivity falls due to scattering processes, which is characteristic for thin inhomogeneous films with thickness less than 15 nm. At the same time, for a sensitive element with thickness of the layer of PTFE of 30 nm, the highest response rate is almost 3 times bigger than shown for saturated acetone vapors. For samples with a thickness of PTFE of 50 nm, energy absorption for thick films was observed, accompanied by an additional expansion of the resonance characteristic and a decrease in the response of the SPR sensor due to a decrease in the area of interaction with the analyte. The sensor response for all studded values of the PTFE thickness on the saturated vapor of acetone was greater than that of saturated vapor of methanol, which may be related to both the different sizes and molar masses of the gas molecules (58.08 g / mol for acetone and 32.04 g / mole for methanol), and with the polarity of the molecules. The concentration dependence of the response of the SPR sensor on the PTFE thicknesses of 30 and 40 nm is linear, and at low concentrations of the test substance, a rather high response for PTFE films (especially acetone) is demonstrated, which is important for the development of gas sensors based on SPR. In terms of the highest sensitivity and selectivity of PTFE film of thickness of 30 nm, it can be used to detect vapors of organic substances and develop gas-SPR sensors.
Keywords: surface plasmon resonance, polytetrafluoroethylene, gas sensor, sensitivity, surface topology.
