Enhancing Parametric Sensitivity in Electrically Coupled MEMS Resonators

Thiruvenkatanathan, Pradyumna; Yan, Jize; Woodhouse, J.; Seshia, Ashwin A.

doi:10.1109/jmems.2009.2025999

Cited by 127 publications

(112 citation statements)

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“…It was demon-20 strated that by measuring the eigenstates shift caused by mode localization, orders of magnitude improvement in sensitivity of mass change was observed [10]. Various groups demonstrated that orders of magnitude enhancement in sensitivity of stiffness change [12,13,14,15] and force [16] could be achieved using this approach. Another advantage of this type of device is its intrinsic 25 common mode rejection [17].…”

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confidence: 99%

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

Zhao

Wood

Xie

et al. 2015

Sensors and Actuators A: Physical

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A force sensor based on three weakly coupled resonators with ultrahigh sensitivity, Sensors & Actuators: A. Physical (2015), http://dx.doi.org/10.1016/j.sna. 2015.05.011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractA proof-of-concept force sensor based on three degree-of-freedom (DoF) weakly coupled resonators was fabricated using a silicon-on-insulator (SOI) process and electrically tested in 20µTorr vacuum. Compared to the conventional single resonator force sensor with frequency shift as output, by measuring the amplitude ratio of two of the three resonators, the measured force sensitivity of the 3DoF sensor was 4.9 × 10 6 /N, which was improved by two orders magnitude. A bias stiffness perturbation was applied to avoid mode aliasing effect and improve the linearity of the sensor. The noise floor of the amplitude ratio output of the sensor was theoretically analyzed for the first time, using the transfer function model of the 3DoF weakly coupled resonator system. It was shown based on measurement results that the output noise was mainly due to the thermalelectrical noise of the interface electronics. The output noise spectral density was measured, and agreed well with theoretical estimations. The noise floor of the force sensor output was estimated to be approximately 1.39nN for an assumed 10Hz bandwidth of the output signal, resulting in a dynamic range of 74.8dB.

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confidence: 99%

“…Assume a quality factor of Q = 2 × 10 4 in vacuum, which is a conservative 245 estimation compared to other similar devices [12,33] and setting |K/K c | = 200, …”

mentioning

confidence: 99%

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

Zhao

Wood

Xie

et al. 2015

Sensors and Actuators A: Physical

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“…[9][10][11][12][13][14] When the resonators are identical, the vibration of the eigenmodes is delocalized over the array. In a similar way to the Anderson's localization, the addition of the mass on one of the resonators leads to the spatial localization of the eigenmodes.…”

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confidence: 99%

Exponential tuning of the coupling constant of coupled microcantilevers by modifying their separation

Gil-Santos¹,

Ramos²,

Pini³

et al. 2011

Applied Physics Letters

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Vibration localization in coupled nanomechanical resonators has emerged as a promising concept for ultrasensitive mass sensing. It possesses intrinsic common mode rejection and the mass sensitivity can be enhanced with no need of extreme miniaturization of the devices. In this work, we have experimentally studied the role of the separation between cantilevers that are elastically coupled by an overhang. The results show that the coupling constant exponentially decays with the separation. In consistency with the theoretical expectations, the mass sensitivity is inversely proportional to the coupling constant. Finite element simulations show that the coupling constant can be exponentially reduced by increasing the ratio of the cantilever separation to the overhang length. © 2011 American Institute of Physics. ͓doi:10.1063/1.3569588͔ Nanomechanical resonators such as vibrating cantilevers, doubly clamped beams, and trampolines to name a few geometries have been proposed for ultrasensitive mass sensing. [1][2][3][4][5] The principle is that molecular adsorption on the surface of the resonator gives rise to an increase in the active mass of the resonator that makes the resonance frequency to decrease. The continuous advancements in top-down microand nanofabrication techniques has made possible increasingly smaller nanomechanical resonators with detection limits in the zeptogram range ͑10 −21 g͒. 6 Moreover, resonant nanowires and nanotubes fabricated by bottom-up methods are on the verge of single atom resolution ͑1.6610 −24 g͒. 7,8 The main disadvantage in the fabrication of extremely small nanomechanical resonators is that the deviations and imperfections inherent to the fabrication at nanoscale makes difficult to obtain reproducible mechanical properties and responses to molecular adsorption. In addition, very large scale integration of these resonators is still technologically complex.An approach that is no longer depending on the extreme miniaturization of the devices is the use of coupled nanomechanical resonators fabricated by standard silicon technology. 9-14 When the resonators are identical, the vibration of the eigenmodes is delocalized over the array. In a similar way to the Anderson's localization, the addition of the mass on one of the resonators leads to the spatial localization of the eigenmodes. 9,10,12 Since vibration localization is insensitive to uniform adsorption, coupled nanomechanical resonators allows decoupling of unspecific and specific molecular adsorption in differentially sensitized resonators. Theoretically, the sensitivity of these devices could be enhanced by reducing the mechanical coupling constant with no need of miniaturization of the nanomechanical resonators. 12 Here we have fabricated coupled mechanical systems consisting of two silicon nitride microcantilevers elastically coupled by an overhang at their base. The aim is to study the dependence of the mass sensitivity on the coupling constant that in this work is tuned by changing the separation between cantilevers.An optical m...

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“…The extent of this vibration energy confinement depends not only on the magnitude of the induced disorder, but also on the strength of internal coupling between the resonators with weaker coupling resulting in stronger localization of the vibration modes [7]. It is also known that weakly coupled, nearly identical resonators exhibit an abrupt divergence of the loci of their eigenvalues when these are plotted against a parameter representing the symmetry-breaking disorder in the system [8,9].…”

Section: Mode Localization and Curve Veeringmentioning

confidence: 99%

“…2. The relative shifts in the magnitudes of the normalized eigenvectors (eigenstates) due to small perturbations in stiffness of one of the resonators may then be expressed as [7] ). 2 , 1 ( ;…”

Section: Mode Localization and Curve Veeringmentioning

confidence: 99%

Ultrasensitive mode-localized micromechanical electrometer

Thiruvenkatanathan

Yan

Seshia

2010

2010 IEEE International Frequency Control Symposium

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Abstract-We report a highly sensitive prototype micromechanical electrometer that employs the phenomena of mode-localization and curve veering for monitoring minute charge fluctuations across an input capacitor. The device consists of a pair of weakly coupled, nearly identical single crystal silicon, double-ended tuning fork (DETF) resonators. An addition of charge across an input capacitor on one of the coupled resonators induces a differential axial strain on that resonator relative to the other consequently perturbing the structural symmetry of the nearly periodic system. The resulting shifts in the eigenstates for the same magnitudes of charge input are theoretically and experimentally demonstrated to be nearly three orders of magnitude greater than corresponding resonant frequency variations. The topology chosen may also be adapted for force or strain monitoring thereby widening the relevance of the results reported here to precision inertial sensing as well.

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Enhancing Parametric Sensitivity in Electrically Coupled MEMS Resonators

Cited by 127 publications

References 20 publications

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

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

Exponential tuning of the coupling constant of coupled microcantilevers by modifying their separation

Ultrasensitive mode-localized micromechanical electrometer

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