High-Qmicromechanical resonators for mass sensing in dissipative media

Abstract

Single crystal silicon-based micromechanical resonators are developed for mass sensing in dissipative media. The design aspects and preliminary characterization of the resonators are presented. For the suggested designs, quality factors of about 20 000 are typically measured in air at atmospheric pressure and 1000–2000 in contact with liquid. The performance is based on a wine-glass-type lateral bulk acoustic mode excited in a rectangular resonator plate. The mode essentially eliminates the radiation of acoustic energy into the sample media leaving viscous drag as the dominant fluid-based dissipation mechanism in the system. For a mass loading distributed over the central areas of the resonator a sensitivity of 27 ppm ng−1 is measured exhibiting good agreement with the results of the finite element method-based simulations. It is also shown that the mass sensitivity can be somewhat enhanced, not only by the proper distribution of the loaded mass, but also by introducing shallow barrier structures on the resonator.

Biosensors based on nanomechanical systems

“…Unfortunately, miniaturization of the resonators to the nanoscale does not help, and may worsen the quality factors [91][92] . Researchers are trying to "catch" the concept of quartz crystal microbalances in which the viscous dissipation is largely minimized when the surface oscillates parallel to the liquid/solid interface instead of transversally as it occurs in singly and doubly clamped beams when they oscillate in flexural modes [93][94][95] . Recently, advances in micro-and nanofabrication have provided micromechanical resonators based on the extensional vibration modes for a variety of mechanical geometries with frequencies of tens of MHz and quality factors in liquids of 1000-2000 93 .…”

“…[95][96][97] Recently, advances in microand nanofabrication have provided micromechanical resonators based on the extensional vibration modes for a variety of mechanical geometries with frequencies of tens of MHz and quality factors in liquids of 1000-2000. 95 These devices hold promise for measuring viscoelastic properties of biological systems with unprecedented sensitivity.…”

A 10 MHz thin-film piezoelectric-on-silicon MEMS resonator with T-shaped tethers forQenhancement

“…16,17) Q is an essential parameter for frequency control applications, and higher Q makes lower insertion loss and better selectivity available, which is desirable for low-phase-noise oscillators and filters. 16,[18][19][20][21] The most relevant sources of energy dissipation in MEMS resonators can be primarily attributed to thermoselastic dissipation (TED), Akhieser effect (AKE), air reflecting and anchor loss. 22,23) By taking into account respective sources of energy dissipation, the overall Q can be estimated as follows:…”

Characterizing the Spatially Dependent Sensitivity of Resonant Mass Sensors Using Inkjet Deposition

“…Microscale devices lend themselves toward sensing applications due to the high sensitivity of their mechanical behavior to changes in system parameters (such as mass, stiffness, or damping), boundary conditions, and various external fields. The promise associated with this high sensitivity has motivated the development of resonant sensors suitable for general mass sensing [1][2][3][4][5], as well as chemical and biological sensing [6][7][8][9][10]. As a specific example, prior art exists wherein resonant microscale sensors are used to detect explosive materials [11,12].…”