¹V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41, Nauky Ave., 03028 Kyiv, Ukraine
²National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, 37, Prospect Beresteiskyi, 03056 Kyiv, Ukraine
*Corresponding author e-mail: gvdorozinsky@ukr.net

Abstract. The effect of the substrate material combined with a polytetrafluoroethylene (PTFE) overlayer on the sensitivity of optical sensors based on surface plasmon resonance (SPR) in the Kretschmann geometry has been investigated. The experiments were performed at a fixed excitation wavelength of surface plasmons using a gold plasmon-supporting layer. The testing of the sensor elements was carried out by cyclic displacement of ambient air by inert helium in the flow cell. A comparative analysis of the characteristics of SPR sensors on substrates made of F1 optical glass and styrene-acrylonitrile (SAN) polymer was carried out in both the presence and absence of a PTFE overlayer on the gold film surface. It was established that replacing the glass substrate with the polymer (SAN) causes an increase in sensitivity from 45.8 to 48.1 deg/RIU due to a decrease in the refractive index; however, it doubles the figure of merit (FOM) from 26.2 to 50.1 RIU–1. The application of the PTFE overlayer for both sensor types led to an increase in sensitivity: from 45.8 to 74.4 deg/RIU for the glass substrate, and from 48.1 to 52.1 deg/RIU for the polymer substrate. In addition to enhanced sensitivity, the use of the polymer material allows for reducing the cost of the final product, simplifying the stages of precision surface treatment. An additional advantage is the narrowing of the resonance curves, which significantly improves the accuracy of the resonance angle registration.

Keywords: sensor, surface plasmon resonance, substrate, polytetrafluoroethylene, styrene-acrylonitrile, helium, sensitivity, figure of merit.

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