Towards Acoustic Radiation Free Lamb Wave Resonators for High-Resolution Gravimetric Biosensing

Abstract

A novel Lamb wave resonator with fully suppressed acoustic radiation in water is proposed for high-resolution masssensitive detection of biomolecules. The elimination of acoustic radiation is achieved by slowing down the Lamb wave to a velocity lower than the sound speed in water. This enables high-qualityfactor resonance in water and reduces the sensing frequency noise. High aspect ratio electrodes (HAREs) are used to slow down the Lamb wave. The elastic resonance and large surface area of the HAREs can also enhance the mass sensitivity of the device. The improved mass sensitivity together with the low frequency noise substantially improves the overall sensing resolution. Although reducing the plate thickness can also slow down the Lamb wave, it makes the device very fragile and not practical to use. In contrast, slowing down the Lamb wave by increasing electrode height allows the use of thick plates which is robust. In this paper, the behavior and performance of the proposed high aspect ratio electrode Lamb wave resonator (HARE-LWR) are theoretically analyzed using finite element method simulations. Optimum design parameters were found through the simulations. Reported results show that a significant figure of merit improvement was achieved by the proposed HARE-LWR design.

Shear Horizontal Phononic Metasurface for In-Liquid Gravimetric Biosensing

“…We chose FEM to evaluate the Q factors and mass sensitivities because the experimental values are usually not reported. The simulation models of HARW-LWR and SH-SAW were previously reported in [8]. The simulated S-FBAR comprises of 2-um aluminum nitride (AlN) sandwiched by two 200-nm aluminum electrodes.…”

“…Nevertheless, the shear polarization cannot prevent the energy leakage through acoustic radiation. To address this problem, phononic metasurface (PM) is introduced 7,8 .…”

Acoustic radiation-free surface phononic crystal resonator for in-liquid low-noise gravimetric detection

“…It was, however, reported that one-dimensional surface phononic crystals (SPCs) made of periodic high aspect ratio electrode strips can be used to significantly slow down Rayleigh waves 20 and Lamb waves 21 . In this paper, we exploit this idea for the realization of SPC resonators operating in liquid.…”

“…The acoustic wave velocity in all piezoelectric substrates is indeed always higher than the sound velocity in water because of the large elastic constants of solid materials. 19 It was however reported that one-dimensional surface phononic crystals (SPC) made of periodic high aspect ratio electrode strips can be used to significantly slow down Rayleigh wave 20 and Lamb wave 21 . In this paper, we exploit this idea for the realization of SPC resonators operating in liquid.…”

Dual-Resonator-Based (DRB) and Multiple-Resonator-Based (MRB) MEMS Sensors: A Review

“…In the past two decades, single-resonator-based (SRB) Micro-Electro-Mechanical-Systems (MEMS) sensors have been extensively studied for detecting small physical or chemical perturbations, such as pressure [1][2][3][4][5][6][7][8], rotational rate [9][10][11][12][13][14], acceleration [15][16][17], vibration [18][19][20], force [21][22][23], chemical vapor [24][25][26], and biological material [27][28][29][30][31][32][33][34]. Various structures, such as flexural mode resonators (FMR) [28,31,35], surface acoustic wave resonators (SAW) [36], bulk acoustic resonators (BAR) [6,12,[24][25][26]37], lamb wave resonators (LWR) [8,14,38], etc., have been fabricated to enable these SRB sensors to ha...…”