Towards optimised wireless Love wave biosensor with high sensitivity

Abstract

A Love wave biosensor, which is composed of a one-port surface acoustic wave reflective delay line on a piezoelectric substrate, a thin overlayer (waveguide layer) on top of the substrate, and a sensitive film that responds only to a specific cell, was optimally designed on a 418 YX LiNbO 3 substrate and then fabricated according to the extracted design parameters. Based on multilayer theory, polymethylmethacrylate waveguide thickness was optimised. For derivation of the coupling of mode parameters, the periodic using the periodic finite-element method/boundary element method modelling was utilised. Optimal interdigital transducers and reflectors' features were determined to realise high-quality reflection peaks. The experimentally measured reflection coefficient S 11 showed good agreement with simulated results. The evaluated sensitivity was 11.5 deg/mg/ml in terms of anti-DNP immunoglobulin G absorption.

Study on Fabrication of ZnO Waveguide Layer for Love Wave Humidity Sensor Based on Magnetron Sputtering

“…The Love wave humidity sensor requires that the shear velocities and densities of the waveguide layer materials are smaller than those of the piezoelectric substrate materials, and the waveguide layer materials were required to have good elastic properties and weak acoustic wave absorption performance [ 11 , 12 , 13 ]. At present, some materials can be used as a waveguide layer of the Love wave device, such as polyimide (PI), poly methyl methacrylate (PMMA), silicon dioxide (SiO 2 ) and zinc oxide (ZnO) [ 14 , 15 , 16 , 17 ].…”