Frequency interference between two mesa-shaped quartz crystal microbalances

Abstract

The multichannel quartz crystal microbalance (MQCM) is very attractive for biosensor applications. The principle of the MQCM design involves fabricating arrays of quartz microbalances on a single substrate, and it is important that the individual sensor performance is not influenced by the neighboring devices. Feasible ways to control the coupling of acoustical energy within a MQCM structure are to increase the difference in the resonance frequency between the electroded and unelectroded portions of the substrate; and a practical way to achieve this is to use mesa structures. In this paper, the frequency interference between two mesa-shaped quartz crystal microbalances is investigated using Mindlin's theory. The results show that even a very small mesa height ( 5% of the plate thickness) can greatly reduce the frequency interference and more effectively trap the acoustic energy. This allows for a broader design window and higher packing density for MQCM applications.

Development of a Flow Injection Based High Frequency Dual Channel Quartz Crystal Microbalance

“…The frequency interference is mainly determined by the spacing between adjacent electrodes, the dimensions and thickness of each electrode, and geometry and frequencies of quartz resonators [17,18]. Several efforts can be made to reduce this kind of interference for modifying the multichannel sensor array configurations, such as mesa structure, inverted mesa structure, bi-mesa or bi-inverted-mesa structures [18,19]. …”

Analysis of the electrically forced vibrations of piezoelectric mesa resonators

“…Energy trapping is mainly due to the inertial effect of the electrodes. [6] Piezoelectric coupling can also contribute to energy trapping, [7] and researchers have developed contoured resonators [8][9][10][11] from plates with gradually varying thicknesses and mesa resonators [12][13][14][15][16][17][18][19][20][21] from plates with stepped or piecewise constant thickness. In contoured or mesa resonators, the changing plate thickness usually leads to stronger energy trapping than the inertia of the partial electrodes.…”

“…Most of Refs. [12]- [21] presented the results on mode variation along the direction of the particle velocity. Only references [18] and [21] have results on mode variation along the direction perpendicular to the particle velocity.…”

Analysis of a Monolithic, Nonperiodic Array of Quartz Crystal Microbalances

“…These in-plane variations make the analysis of QCM arrays very difficult. Arrays of QCRs, 21) QCMs, [22][23][24] and transducers, 25) have been analyzed using the approximate equations for piezoelectric plates derived in Refs. 26 and 27.…”