Limits to mode-localized sensing using micro- and nanomechanical resonator arrays

Abstract

In recent years, the concept of utilizing the phenomenon of vibration mode-localization as a paradigm of mechanical sensing has made profound impact in the design and development of highly sensitive micro-and nanomechanical sensors. Unprecedented enhancements in sensor response exceeding three orders of magnitude relative to the more conventional resonant frequency shift based technique have been both theoretically and experimentally demonstrated using this new sensing approach. However, the ultimate limits of detection and in consequence, the minimum attainable resolution in such mode-localized sensors still remain uncertain. This paper aims to fill this gap by investigating the limits to sensitivity enhancement imposed on such sensors, by some of the fundamental physical noise processes, the bandwidth of operation and the noise from the electronic interfacial circuits. Our analyses indicate that such mode-localized sensors offer tremendous potential for highly sensitive mass and stiffness detection with ultimate resolutions that may be orders of magnitude better than most conventional micro-and nanomechanical resonant sensors.

Closed-Loop Characterization of Noise and Stability in a Mode-Localized Resonant MEMS Sensor

“…1) Thermal Noise: The thermal noise originates from the intrinsic Brownian motion of the particles of mass in the resonators. Using the transfer function approach as outlined in Appendix A, the noise power of the amplitude noise can be modeled (assuming that the thermal noise is a driving force) as [34]:…”

A force sensor based on three weakly coupled resonators with ultrahigh sensitivity

“…For a standard transimpedance amplifier, the input-referred current noise 260 power spectral density can be expressed as [31]:…”

Inverse eigenvalue sensing with corner coupled square plate MEMS resonators array

“…Theoretically, the maximum number of resonators in a coupled array is limited by the mode liaison effect, i.e. n\jQ % 100 [20]. Hence we have fabricated larger arrays of twenty to fifty coupled resonators, which will be tested and used as sensors in our future work.…”

“…Since the sensitivity of coupled resonators is highly dependent on the coupling ratio [20], it is important to optimise the design before using them as sensors. To understand how the geometry of these mechanical beams affects coupling ratio, resonators with different coupling beam lengths and widths can be …”