scholarly journals A Sub-1 Hz Resonance Frequency Resonator Enabled by Multi-Step Tuning for Micro-Seismometer

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 63
Author(s):  
Jun Wu ◽  
Hideyuki Maekoba ◽  
Arnaud Parent ◽  
Tamio Ikehashi
Keyword(s):  
Resonance Frequency ◽  
Frequency Shift ◽  
Dynamic Range ◽  
Spring Constant ◽  
Tuning Method ◽  
Mems Resonator ◽  
Mass Displacement ◽  
Fine Tune

We propose a sub-1 Hz resonance frequency MEMS resonator that can be used for seismometers. The low resonance frequency is achieved by an electrically tunable spring with an ultra-small spring constant. Generally, it is difficult to electrically fine-tune the resonance frequency at a near-zero spring constant because the frequency shift per voltage will diverge at the limit of zero spring constant. To circumvent this issue, we propose a multi-step electrical tuning method. We show by simulations that the resonance frequency can be tuned by 0.008 Hz/mV even in the sub-1 Hz region. The small spring constant, however, reduces the shock robustness and dynamic range of the seismometer. To prevent this, we employ a force-balanced method in which the mass displacement is nulled by the feedback force. We show that the displacement can be obtained from the voltage that generates the feedback force.

Reliability and stability of thin-film amorphous silicon MEMS on glass substrates

2011 ◽  
Vol 1299 ◽  
Author(s):  
P. M. Sousa ◽  
V. Chu ◽  
J. P. Conde
Keyword(s):  
Thin Film ◽  
Resonance Frequency ◽  
Frequency Shift ◽  
Amorphous Silicon ◽  
Structural Damage ◽  
Chemical Vapor ◽  
Stability Study ◽  
Glass Substrates ◽  
Resonance Frequency Shift ◽  
Mems Resonators

ABSTRACTIn this work, we present a reliability and stability study of doped hydrogenated amorphous silicon (n+-a-Si:H) thin-film silicon MEMS resonators. The n+-a-Si:H structural material was deposited using radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) and processed using surface micromachining at a maximum deposition temperature of 110 ºC. n+-a-Si:H resonant bridges can withstand the industry standard of 1011 cycles at high load with no structural damage. Tests performed up to 3x1011 cycles showed a negligible level of degradation in Q during the entire cycling period which in addition shows the high stability of the resonator. In measurements both in vacuum and in air a resonance frequency shift which is proportional to the number of cycles is established. This shift is between 0.1 and 0.4%/1x1011 cycles depending on the applied VDC. When following the resonance frequency in vacuum during cyclic loading, desorption of air molecules from the resonator surface is responsible for an initial higher resonance frequency shift before the linear dependence is established.

scholarly journals Correcting heat-induced chemical shift distortions in proton resonance frequency-shift thermometry

2015 ◽  
Vol 76 (1) ◽  
pp. 172-182 ◽  
Author(s):  
Pooja Gaur ◽  
Ari Partanen ◽  
Beat Werner ◽  
Pejman Ghanouni ◽  
Rachelle Bitton ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Resonance Frequency ◽  
Frequency Shift ◽  
Proton Resonance Frequency ◽  
Proton Resonance ◽  
Proton Resonance Frequency Shift ◽  
Resonance Frequency Shift

Investigation on Resonance Effects of Closely Resonating Nano-Pillars Attached to SAW Resonator

2011 ◽  
Vol 403-408 ◽  
pp. 1183-1187
Author(s):  
N. Ramakrishnan ◽  
Harshal B. Nemade ◽  
Roy Paily Palathinkal
Keyword(s):  
Acoustic Wave ◽  
Resonance Frequency ◽  
Frequency Shift ◽  
Fem Simulation ◽  
Mass Loading ◽  
Loading Effect ◽  
Resonance Effects ◽  
Additional Information ◽  
Resonance Frequency Shift ◽  
Small Change

Surface acoustic wave (SAW) sensors form an important class of micro sensors in the microelecto mechanical systems (MEMS) family. Mass loading effect of a sensing medium is one of the prime sensing principles in SAW sensors. Recently we reported mass loading effect of high aspect ratio nano-pillars attached to a SAW resonator. We observed increase in resonance frequency of the SAW resonator in addition to the general mass loading characteristics. We concluded that when the resonance frequency of the pillar is equal to the SAW resonator frequency, the resonance frequency shift caused by mass loading of pillar tends to a negligible value. When such resonating pillars are used as sensing medium in SAW sensors, even a very small change in the dimension of the pillar will offer significant resonance frequency shift. Accordingly, high sensitive SAW sensors can be developed. However in practice it’s quite difficult to manufacture nano-pillars with accurate dimensions such that they resonate with SAW resonator. There is more probability that the pillars may closely resonate with SAW device and offer mass loading. In the present work we have extended our earlier work and performed finite element method (FEM) simulation to study the insight physics of the closely resonating pillars and their effects on acoustic wave propagating on SAW substrate. In this paper we present the discussion on the resonance effects of typical closely resonating pillars on resonance frequency spectrum of the SAW resonator and observations in the pressure wave at the contact surface of the pillar and SAW resonator substrate. It is observed that when the nano-pillars closely resonate with SAW resonator, the pillar oscillations combine with waves propagating in the substrate and introduce beat frequencies. The results and discussion of this paper adds additional information in designing SAW based coupled resonating systems.

scholarly journals CO Gas-Induced Resonance Frequency Shift of ZnO-Functionalized Microcantilever in Humid Air

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Lia Aprilia ◽  
Ratno Nuryadi ◽  
Dwi Gustiono ◽  
Nurmahmudi ◽  
Arief Udhiarto ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Zinc Oxide ◽  
Water Vapor ◽  
Resonance Frequency ◽  
Frequency Shift ◽  
Hydrothermal Method ◽  
Gas Flow ◽  
Humid Air ◽  
Resonance Frequency Shift ◽  
Co Gas

Resonance frequency shift of a zinc oxide- (ZnO-) functionalized microcantilever as a response to carbon monoxide (CO) gas has been investigated. Here, ZnO microrods were grown on the microcantilever surface by a hydrothermal method. The measurement of resonance frequency of the microcantilever vibrations due to the gas was carried out in two conditions, that is, gas flow with and without air pumping into an experiment chamber. The results show that the resonance frequency of the ZnO-functionalized microcantilever decreases because of CO in air pumping condition, while it increases when CO is introduced without air pumping. Such change in the resonance frequency is influenced by water vapor condition, and a possible model based on water-CO combination was proposed.

Real-Time Measurement Method of Doppler Based on GPS Carrier Signals

2012 ◽  
Vol 226-228 ◽  
pp. 2050-2055 ◽  
Author(s):  
Shao Feng Dong ◽  
Bao Qiang Du ◽  
Wei Zhou
Keyword(s):  
Frequency Shift ◽  
Real Time ◽  
Measurement Method ◽  
Dynamic Range ◽  
Time Synchronization ◽  
Influencing Factor ◽  
Doppler Frequency ◽  
Time Measurement ◽  
Time Frequency ◽  
Real Time Measurement

According to Doppler effect of satellite on the time synchronization technology between satellite and the ground station, a real-time measurement method of Doppler is proposed based on GPS carrier signals. Using Doppler observations from GPS receiver, the method can real-timely measure Doppler frequency shift of GPS including dynamic Doppler and media Doppler whose error can be timely modified in the receiver end. Simulation results show that the frequency shift caused by dynamic Doppler, a main influencing factor in the course of transmission of time-frequency signal by GPS satellite, is between plus or minus several thousands Hz. Comparing to traditional measurement method of Doppler, the method makes it possible to fast track phase of signal in large dynamic range in synchronous technology.

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