An optical vapor sensor based on amphiphilic block copolymer langmuir-blodgett films

Amphiphilic block copolymers containing poly [N,N-(dimethylamino)ethyl methacrylate] block was used as a chemical sensor material in this paper. The amphiphilic block copolymer Langmuir-Blodgett (LB) thin films were prepared onto a gold-coated glass, quartz crystal and quartz glass substrates to fabricate a thin film chemical sensor element. Atomic force microscopy, quartz crystal microbalance, UV-visible spectroscopy, and surface plasmon resonance (SPR) techniques were used to characterize all the copolymer LB thin films. The mass deposited onto a quartz crystal and the frequency shifts per layer were found to be 4258.01 ng per layer (16.06 ng mm-2) and 188.07 Hz per layer, respectively. Using Winspall software, all experimental SPR data were fitted and the film thickness of this the copolymer LB thin film can be evaluated. The refractive index and thickness per monolayer of LB films were determined as 1.63±0.02 nm and 1.46±0.07 nm, respectively. Amphiphilic block copolymer LB thin film chemical sensor element was exposed to dichloromethane, chloroform, benzene, and toluene vapors. The SPR kinetic measurements showed that the photodetector response change, ? Irf for saturated dichloromethane vapor is much larger than the other vapors with the ? Irf value of 0.081 au and with 3.5-s recovery time/4.5-s response time. It can be proposed that amphiphilic block copolymer LB thin film chemical sensor element has a good sensitivity and selectivity for saturated dichloromethane vapor. © 2001-2012 IEEE.113Z584Manuscript received April 19, 2018; accepted May 2, 2018. Date of publication May 7, 2018; date of current version June 12, 2018. This work was supported by The Scientific and Technical Research Council of Turkey under Project 113Z584. The associate editor coordinating the review of this paper and approving it for publication was Dr. Qiang Wu. (Corresponding author: Yaser Acikbas.) Y. Acikbas is with the Department of Material Science and Nanotechnology Engineering, Faculty of Engineering, Us¸ak University, 64200 Us¸ak, Turkey (e-mail: yaser.acikbas@usak.edu.tr)