Response of a Pt-polyyne membrane in surface acoustic wave sensors: Experimental and theoretical approach

A surface acoustic wave (SAW) sensor, based on a polymeric sensitive membrane, has been realized for sensor applications and materials characterization. A platinum-containing rigid-rod organometallic polymer [-Pt(PPh3)(2)(-C=C-pC(6)H(2)(2,5-OC16H33)(2)-C=C-)](n) (Pt-P-HDOB), obtained by the reaction of cis-[Pt(PPh3)(2)Cl-2] with 1,4-diethynyl-2,5-dihexadeciloxybenzene (HDOB) by means of the recently assessed "Extended one pot" polymerization route, was here studied. The chemical structure and chain length of Pt-P-HDOB polymer were defined by spectroscopic techniques and gel permeation chromatography measurements. The acoustic characterization of the Pt-P-HDOB film was developed with the aid of the perturbation theory applied to different polymer-coated-piezoelectric substrates and the shear modulus of Pt-P-HDOB film have been estimated. A SAW delay line has been implemented on ZnO/Si substrate and a thin polymeric film has been spin deposited on the device surface to realize a chemical sensor. The sensor has been exposed to different chemicals and its response has been measured for different chemical concentrations. High sensitivity and reproducibility of the sensor response to relative humidity and methanol vapors were found. (C) 2003 American Institute of Physics.