A new efficient combined FEM and periodic Green's function formalism for the analysis of periodic SAW structures

A rigorously derived Green's function is applied to a surface acoustic wave (SAW) sensor, operating with a layer above the inter-digital transducer (IDT) and including the effects of a liquid loading. The extracted reflection, transduction and capacitance values are suitable for utilisation in the design of surface and plate mode sensors. This technique was applied to devices on 36 • -YX LiTaO 3 , with guiding layers of SiO 2 and ZnO.

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“…[3]). In this paper it is applied to SAW sensors, and is shown to yield useful information for sensor design.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive analysis of SAW sensor performance in liquid media by Green's function method

Powell

Kalantar‐zadeh

Włodarski

IEEE Symposium on Ultrasonics, 2003

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“…Here, [Z] is an impedance matrix, which can be deduced by the periodic Green tensor of the piezoelectric crystal half space [10]. Combining (3) and (4), the periodic FEM/BEM formula is obtained (5) By solving the formula, we obtained the charge on the electrode, and further calculated the admittance.…”

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confidence: 99%

Towards optimised wireless Love wave biosensor with high sensitivity

Jung

Yang

et al. 2012

Micro Nano Lett.

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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.

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“…The determination of the grating harmonic admittance has been the main goal of many theoretical and numerical works; we use in this paper a method due to Ventura et a1 [6]. The addressed problem is treated using an integral representation of the substrate surface assuming a semi-infinite medium, the so-called boundary integral method (BUI), connected through a discrete formulation to the diffracting elements in the structure, i.e.…”

Section: Theorymentioning

confidence: 99%

“…As proposed by several authors [6,9], a Chebyshev polynomial expansion of the electromechanical fields can be used with benefits. A matrix equation relating the Chebyshev expansion coefficients of the electromechanical fields in the substrate can be obtained [6].…”

Section: Theorymentioning

confidence: 99%

“…A matrix equation relating the Chebyshev expansion coefficients of the electromechanical fields in the substrate can be obtained [6]. An infinitely thin electrode is assumed for the electrical behavior of the metal; this assumption is supported by the observation that if the permittivity of the substrate is much larger than that of air, then charges are most likely to be located at the substratemetal interfacc than at the air-.…”

Section: Theorymentioning

confidence: 99%

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Electroacoustic interaction between SAW and vibration modes of high-aspect-ratio electrodes built using LIGA-UV techniques on singly rotated lithium niobate wafers

Robert¹,

Laude²,

Basrour³

et al.

2001 Microelectromechanical Systems Conference (Cat. No. 01EX521)

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Abstnrcl-It has been shown theoretically and demonstrated experimentally that shear horizontal surface waves can exist when the surface of an isotropic substrate is perturbed by a strong corrugation, for instance consisting of deep grooves etched in the substrate, whereas these waves cannot exist without this perturbation. In this work, we analyze the behavior of surface acoustic waves with general Polarization propagating under a periodic array of metallic electrodes with large aspect ratio, deposited over a piezoelectric substrate. In this case, we had previously predicted the existence of generally polarized higher order surface modes. We have constructed high-aspectratio interdigital transducers (IDT's) on Y+128 lithium niobate using electroplating techniques. We have observed the existence of higher order surface modes using electrical measurements of the admittance of the IDT's. The predicted and experimental results agree reasonably well, although more work is required to fully understand the properties of these higher order surface modes of high-aspect -ratio IDT's. I. INTRODIJCXIONSurface Acoustic Wave (SAW) devices are widely used in telecommunicabon for frequency filtering operations. Most of these devices uqes thin electrodes to excite and guide surface waves at the top of piezoelectric substrates such as Quartz, Lithium Tantalate or Lithium Niobate. It is well known that surface waves (Rayleigh, Leaky-SAW, etc.) are affected by thc mass loading due to the-electrode gratings deposited atop the propagation surface. Previous works [ 1,2] have shown the possibility to excite and guide on an isotropic substrate more than one surface mode (shear horizontal) under very thick aluminum gratings (electrode heighv'acoustic wavelength ratio greater than 25%), allowing a multimodal response of SAW devices based on such principle. In a recent theoretical work [3,4], we have analyzed the interaction betwecn eigenmodes of thick electrodes and surface wave propagation. A generally polarized wave was assumed to propagate under metallic periodic gratings, and two different calculation approaches were implemented to simulate the electroacoustic response of such devices, respectively based on the combination of Finite Element Analysis (FEA) and Boundary Integral Methods (BIM) [5,6] and on pure FEA computations. No other assumptions than propagation in the sagittal plane are being made. Various piezoelectric substrates have been considered as potential candidates, including Y+128 lithium niobate, Y+36 lithium tantalate and ST quartz. As the electrode height is gradually increased, different waves are found to be guided under the grating, exhibiting either shear horizontal, sagittal or even general elastic polarization.In this paper, we report on experimcnts that have been performed using Y+128 lithium niobate wafcrs in the intent to show the existence of these higher order modcs. Periodic nickel gratings have been realized using deep etch UV lithography and electroplating techniques. Single and two port SAW resonators hav...

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A new efficient combined FEM and periodic Green's function formalism for the analysis of periodic SAW structures

Cited by 77 publications

References 3 publications

Comprehensive analysis of SAW sensor performance in liquid media by Green's function method

Comprehensive analysis of SAW sensor performance in liquid media by Green's function method

Towards optimised wireless Love wave biosensor with high sensitivity

Electroacoustic interaction between SAW and vibration modes of high-aspect-ratio electrodes built using LIGA-UV techniques on singly rotated lithium niobate wafers

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