Perturbation Analysis of a Multiple Layer Guided Love Wave Sensor in a Viscoelastic Environment.

Tao Wang,Shyam S Mohapatra,Ryan Murphy,Jing Wang,Subhra Mohapatra,Rasim Guldiken

doi:10.3390/s19204533

Tao Wang, Shyam S Mohapatra + Show 4 more

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https://doi.org/10.3390/s19204533

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Abstract

Surface acoustic wave sensors have the advantage of fast response, low-cost, and wireless interfacing capability and they have been used in the medical analysis, material characterization, and other application fields that immerse the device under a liquid environment. The theoretical analysis of the single guided layer shear horizontal acoustic wave based on the perturbation theory has seen developments that span the past 20 years. However, multiple guided layer systems under a liquid environment have not been thoroughly analyzed by existing theoretical models. A dispersion equation previously derived from a system of three rigidly coupled elastic mass layers is extended and developed in this study with multiple guided layers to analyze how the liquid layer’s properties affect the device’s sensitivity. The combination of the multiple layers to optimize the sensitivity of an acoustic wave sensor is investigated in this study. The Maxwell model of viscoelasticity is applied to represent the liquid layer. A thorough analysis of the complex velocity due to the variations of the liquid layer’s properties and thickness is derived and discussed to optimize multilayer Surface acoustic wave (SAW) sensor design. Numerical simulation of the sensitivity with a liquid layer on top of two guided layers is investigated in this study as well. The parametric investigation was conducted by varying the thicknesses for the liquid layer and the guided layers. The effect of the liquid layer viscosity on the sensitivity of the design is also presented in this study. The two guided layer device can achieve higher sensitivity than the single guided layer counterpart in a liquid environment by optimizing the second guided layer thickness. This perturbation analysis is valuable for Love wave sensor optimization to detect the liquid biological samples and analytes.

Highlights

Biosensors are used in a broad range of applications such as clinical diagnosis [1], biomedical devices [2,3,4], food production and analysis [5,6], microbiology [7,8], pharmaceutical and drug analysis [9,10], pollution control and monitoring [11], and military applications [12,13]
When a guided layer of finite thickness is deposited on a semi-infinite thick substrate, the Love wave can be characterized by a slower shear wave velocity on the guided layer which can result in a very high sensitivity due to their acoustic energy concentration in the layer [22]
This study aims to investigate how the thicknesses and properties of each layer influence the sensitivity in a four-layer design with multiple guided layers and a liquid layer on top

Summary

Introduction

Biosensors are used in a broad range of applications such as clinical diagnosis [1], biomedical devices [2,3,4], food production and analysis [5,6], microbiology [7,8], pharmaceutical and drug analysis [9,10], pollution control and monitoring [11], and military applications [12,13]. The Love wave sensor is mainly based on the shear horizontal wave because of its high sensitivity as compared to the traditional acoustic wave-based device designs. These waves propagate in a layered structure consisting of a substrate and a guided layer on its top, which increases the sensitivity and the coupling coefficient due to the waveguide effect [23]. Due to the high sensitivity, low cost, and capability of wireless interfacing, the surface acoustic wave-based biosensors are a promising candidate for fluidic sensor applications

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