Abstract
The thermomechanical motion imposes the fundamental noise limit in room-temperature resonant sensors and oscillators. Due to the inherently low sensitivity of capacitive transduction in microelectromechanical (MEM) resonators, its effects are often masked by noise in the subsequent amplifier and measurement stages. In this work, we demonstrate a capacitive transduction scheme for measuring kHz-MHz frequency MEM resonators across 1 $\mu \text{m}$ capacitive gaps with 99.8% thermomechanical-noise-limited resolution. We delineate the transimpedance gain and noise of our custom off-chip differential transimpedance amplifier setup. The thermomechanical noise spectrum can provide estimates of the resonant frequency, quality factor, and electromechanical transduction factor comparable to the commonly used driven response, without the downsides of capacitive feedthrough or nonlinearity. [2019-0115]
Highlights
M ICROELECTROMECHANICAL resonators are playing an increasing role in commercial oscillators [1], filters [2], [3], and atomic force microscopes ( [4], [5]) for measuring biological materials [6]–[8], microfluidic resonators for cell characterization [9]–[11], and studying nanoscale energy transport [12]–[14]
Capacitive transduction is not precluded from achieving excellent measurement resolution; when micromechanical resonators are cooled to cryogenic temperatures and nanometer-scale gaps are employed, capacitive sensing can detect down to the quantum noise level, more than ten orders of magnitude smaller than the thermomechanical noise motion at room-temperature
By comparing measurements of a micromechanical beam actuated by an external electrostatic drive or thermomechanical noise to an electromechanical model, we show that the thermomechanical noise and driven response yield similar estimates for the electromechanical transduction factor and the gap size
Summary
M ICROELECTROMECHANICAL resonators are playing an increasing role in commercial oscillators [1], filters [2], [3], and atomic force microscopes ( [4], [5]) for measuring biological materials [6]–[8], microfluidic resonators for cell characterization [9]–[11], and studying nanoscale energy transport [12]–[14]. With careful amplifier design and sufficiently narrow gaps, the noise of a capacitively-transduced MEM sensor or oscillator can be limited by the thermomechanical noise near the mechanical resonance frequencies instead of the noise in the subsequent amplifier stages. Capacitive transduction is not precluded from achieving excellent measurement resolution; when micromechanical resonators are cooled to cryogenic temperatures and nanometer-scale gaps are employed, capacitive sensing can detect down to the quantum noise level, more than ten orders of magnitude smaller than the thermomechanical noise motion at room-temperature This can be accomplished by capacitively coupling the mechanical resonator to a superconducting single-electron transistor [48], [49] or a superconducting microwave circuit with a Josephson parametric amplifier readout [50], [51]. By comparing measurements of a micromechanical beam actuated by an external electrostatic drive or thermomechanical noise to an electromechanical model, we show that the thermomechanical noise and driven response yield similar estimates for the electromechanical transduction factor and the gap size
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
