scholarly journals A Battery-Less Wireless Respiratory Sensor Using Micro-Machined Thin-Film Piezoelectric Resonators

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 363
Author(s):  
Sina Moradian ◽  
Parvin Akhkandi ◽  
Junyi Huang ◽  
Xun Gong ◽  
Reza Abdolvand
Keyword(s):  
Resonance Frequency ◽  
Excitation Power ◽  
Mems Devices ◽  
Uhf Rfid ◽  
Low Loss ◽  
Resonance Modes ◽  
Mems Resonator ◽  
Respiration Sensor ◽  
Exhaled Air ◽  
The Difference

In this work, we present a battery-less wireless Micro-Electro-Mechanical (MEMS)-based respiration sensor capable of measuring the respiration profile of a human subject from up to 2 m distance from the transceiver unit for a mean excitation power of 80 µW and a measured SNR of 124.8 dB at 0.5 m measurement distance. The sensor with a footprint of ~10 cm2 is designed to be inexpensive, maximize user mobility, and cater to applications where disposability is desirable to minimize the sanitation burden. The sensing system is composed of a custom UHF RFID antenna, a low-loss piezoelectric MEMS resonator with two modes within the frequency range of interest, and a base transceiver unit. The difference in temperature and moisture content of inhaled and exhaled air modulates the resonance frequency of the MEMS resonator which in turn is used to monitor respiration. To detect changes in the resonance frequency of the MEMS devices, the sensor is excited by a pulsed sinusoidal signal received through an external antenna directly coupled to the device. The signal reflected from the device through the antenna is then analyzed via Fast Fourier Transform (FFT) to extract and monitor the resonance frequency of the resonator. By tracking the resonance frequency over time, the respiration profile of a patient is tracked. A compensation method for the removal of motion-induced artifacts and drift is proposed and implemented using the difference in the resonance frequency of two resonance modes of the same resonator.

Dynamic behaviours of the Double-end tuning fork based comb-driven microelectromechanical resonators for modulating the magnetic flux synchronously

2021 ◽  
Author(s):  
Zhenxi Liu ◽  
Jiamin Chen ◽  
Wuhao Yang ◽  
Tianyi Zheng ◽  
Qifeng Jiao ◽  
...  
Keyword(s):  
Detection Limit ◽  
Magnetic Flux ◽  
Resonance Frequency ◽  
Tuning Fork ◽  
Paper Making ◽  
Initial Space ◽  
Mems Resonator ◽  
Mems Resonators ◽  
Mems Fabrication ◽  
First Time

Abstract MEMS resonators have been widely used in the magneto-resistive (MR) sensor for modulating the magnetic flux to enhance the detection limit. However, the manufacturing tolerances in MEMS fabrication processes make it challenging to fabricate the identical resonators with the same vibration frequency, which greatly decreases the detection limit of the MR sensor. To synchronize the MEMS resonators and improve the performance of the MR sensor, the double end tuning fork (DETF) based comb-driven MEMS resonators is proposed in this paper, making the system operate at the out-of-phase mode to complete the synchronization. The dynamic behaviour of the resonators is investigated through theoretical analysis, numerical solution based on MATLAB code and Simulink, and experimental verification. The results show that the transverse capacitances in the comb will significantly affect the resonance frequency due to the second-order electrostatic spring constant. It is the first time to observe the phenomenon that the resonant frequency increases with the increase of the bias, and it can also decrease with increasing the bias through adjusting the initial space between the fixed finger and the moving mass, they are different from the model about spring softening and spring hardening. Besides, the proposed DETF-based comb-driven resonators can suppress the in-phase and out-of-phase mode through adjusting the driving and sensing ports, and sensing method, meanwhile make the magnetic flux modulation fully synchronized, and maximize the modulation efficiency, and minimize the detection limit. These characteristics are appropriate for the MR sensor, even other devices that need to adjust the resonance frequency and vibration amplitude. Furthermore, the model and the design can also be extended to characteristic the single end tuning fork (SETF) based MEMS resonator and other MEMS-based MR sensors.

Test Method of the εrms-N Curves of Laminated Composite Beams

2008 ◽  
Vol 44-46 ◽  
pp. 311-316
Author(s):  
Chuang Shao ◽  
Sen Ge ◽  
Hua Tao ◽  
Claude Bathias
Keyword(s):  
Resonance Frequency ◽  
Fatigue Test ◽  
Laminated Composite ◽  
Test Method ◽  
Cantilever Beams ◽  
Test Results ◽  
Vibration Fatigue ◽  
The Difference ◽  
Double Cantilever Beams ◽  
Laminated Composite Beams

Two kinds of beam specimens made of composite laminated panel were designed and used to do vibration fatigue test for ε-N curves. the shapes of various simulated joint configurations for the specimens were adopted in order to get the accurate results. They were two kinds of double-cantilever beams supplied by T-mode stiffener and L-mode stiffener. All beam specimens were tested under the same shape of narrowband spectrum and the several loadings of random vibration by shaker excitation. The bandwidth of the narrowband random spectrum was 1/3 octave bandwidth whose centre frequency was the first resonance frequency of the cantilever beam, so that it reduced influences of the difference of specimens resonance frequency. Fitting vibration fatigue test results, the ε-N curves would be obtained then. The vibration test shows that this method of getting ε-N vibration curve is feasible. It can be used in practice.

An integrated self-masking technique for providing low-loss metallized RF MEMS devices in a polysilicon only MEMS process (Invited Paper)

2005 ◽  
Author(s):  
John M. Wilson ◽  
Rizwan Bashirullah ◽  
David P. Nackashi ◽  
David A. Winick ◽  
Paul D. Franzon
Keyword(s):  
Rf Mems ◽  
Mems Devices ◽  
Low Loss ◽  
Mems Process

EVALUATION OF TAG MOVING DIRECTION DETECTION IN A UHF RFID GATE SYSTEM

2012 ◽  
Vol 21 (06) ◽  
pp. 1240015 ◽  
Author(s):  
YOSHINORI OIKAWA
Keyword(s):  
Inventory Management ◽  
Uhf Rfid ◽  
Bar Code ◽  
Received Power ◽  
Long Read ◽  
Direction Detection ◽  
Moving Direction ◽  
Gate System ◽  
The Difference ◽  
Rf Tags

A UHF-band RFID system handling many RF tags has some advantages over a bar code system such as simultaneous multi-reading and long read range. Especially, it has been strongly desired by the logistics and the retail industries for efficiency of operation. Recently, user-friendly RFID systems are being studied. We focused on a gate system using RFID technologies. If the tag moving direction can be recognized at the RFID gate system, it will be very useful for the efficiency of inventory management and the checking of pilferage or shoplifting. In this paper, new methods of tag moving direction detection using the difference of passing time of two antennas without expensive external sensors is proposed and evaluated. Two methods are proposed for the specific procedure. The first one is to detect the time when the received power goes over the preset threshold. The second one is to estimate the aimed time using the maximum likelihood approach. Some experimental results of these methods are also shown and their feasibility is proved.

scholarly journals Multilayer Strip Dipole Antenna Using Stacking Technique and Its Application for Curved Surface

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Charinsak Saetiaw ◽  
Chanchai Thongsopa
Keyword(s):  
Resonance Frequency ◽  
Frequency Response ◽  
Dipole Antenna ◽  
Curved Surface ◽  
Uhf Rfid ◽  
Laminate Layer ◽  
Rfid Applications

This paper presents the design of multilayer strip dipole antenna by stacking a flexible copper-clad laminate utilized for curved surface on the cylindrical objects. The designed antenna will reduce the effects of curving based on relative lengths that are changed in each stacking flexible copper-clad laminate layer. Curving is different from each layer of the antenna, so the resonance frequency that resulted from an extended antenna provides better frequency response stability compared to modern antenna when it is curved or attached to cylindrical objects. The frequency of multilayer antenna is designed at 920 MHz for UHF RFID applications.

Investigation of Ultralow Loss Interconnection Technique for LTCC based System-in-Package(SIP) Technology at 60GHz

2006 ◽  
Vol 969 ◽  
Author(s):  
Dong-Young Kim ◽  
Jae Kyoung Mun ◽  
Dong-Suk Jun ◽  
Haechoen Kim
Keyword(s):  
Transmission Lines ◽  
Insertion Loss ◽  
Return Loss ◽  
Frequency Range ◽  
Transmission Characteristics ◽  
Transition Structure ◽  
Low Loss ◽  
Signal Line ◽  
The Difference ◽  
Packaging Module

AbstractThe effects of wire and ribbon bond interconnection on the transmission characteristics at millimeter wave frequency range was presented. The insertion loss and return loss was closely related with the ratio of the signal line width to that of bonded wire or ribbon. The most promise condition for low loss interconnection was that the width of bonded wire or ribbon should be compatible to the width of signal lines. In the actual fabrication of LTCC amp module, the insertion loss of packaging is very small which means that the loss due to bonding is nearly negligible. However, the S11 and S22 degraded severely due to the difference of the types of transmission lines between chip and packaging module. A new transition structure was introduced in order to compensate this difference of transmission lines.

Adsorption-Induced Failure Modes of Thin-Film Resonators

2001 ◽  
Vol 695 ◽  
Author(s):  
R. Kazinczi ◽  
J.R. Mollinger ◽  
A. Bossche
Keyword(s):  
Thin Film ◽  
Resonance Frequency ◽  
Failure Modes ◽  
Surface Oxidation ◽  
Ambient Air ◽  
Mems Devices ◽  
Initial Drop ◽  
The Stability ◽  
Thin Film Resonators ◽  
Stiffening Effect

ABSTRACTThe mechanical and resonant properties of thin film resonators are influenced by the surrounding environment. Adsorption- and surface oxidation-induced stiffening effect was observed on silicon nitride and silicon carbide cantilever beams. The resonance frequency increased logarithmically in time upon exposure to ambient air. The variations of surface stress and spring constant of the SiNx cantilever beam were calculated. Further oxynitride formation on the surface increased the stability of the resonators. The shock response of the structures was studied in various environments. The resonance frequency abruptly dropped due to cracking of the absorbed surface layer, than recovered logarithmically. The initial drop and the recovery rate is environment dependant. Humidity increased, while argon and nitrogen rich environments mitigated the degrading effects. The SiCx is more inert to the environmental effects and proved to be a promising candidate as structural material in resonant MEMS devices.

Defect-Induced Shifts in the Elastic Constants of Silicon

2002 ◽  
Vol 741 ◽  
Author(s):  
Clark L. Allred ◽  
Jeffrey T. Borenstein ◽  
Marc S. Weinberg ◽  
Xianglong Yuan ◽  
Martin Z. Bazant ◽  
...  
Keyword(s):  
Elastic Constants ◽  
Atomistic Simulations ◽  
Device Performance ◽  
Mems Devices ◽  
Materials Properties ◽  
Radiation Induced ◽  
Mems Device ◽  
The Difference ◽  
Induced Defects ◽  
Constant Shift

ABSTRACTAs MEMS devices become ever more sensitive, even slight shifts in materials properties can be detrimental to device performance. Radiation-induced defects can change both the dimensions and mechanical properties of MEMS materials, which will be of concern to designers of MEMS for applications involving radiation exposure, such as those in a reactor environment or in space. We have performed atomistic simulations of the effect that defects and amorphous regions, such as could be produced by radiation damage, have on the elastic constants of silicon. We have then applied the results of the elastic constant shift calculations to a hypothetical MEMS device, and calculated the difference that would be generated by this effect.

scholarly journals MEMS resonator mass loading noise model: The case of bimodal adsorbing surface and finite adsorbate amount

2021 ◽  
Vol 34 (3) ◽  
pp. 367-380
Author(s):  
Ivana Jokic ◽  
Olga Jaksic ◽  
Milos Frantlovic ◽  
Zoran Jaksic ◽  
Koushik Guha
Keyword(s):  
Microelectromechanical Systems ◽  
Noise Model ◽  
Stable Operation ◽  
Mass Loading ◽  
Mems Devices ◽  
Design Development ◽  
Resonant Sensors ◽  
Mems Resonator ◽  
Novel Approach ◽  
Adsorption Desorption

Modeling of adsorption and desorption in microelectromechanical systems (MEMS) generally is crucial for their optimization and control, whether it is necessary to decrease the adsorption-desorption influence (thus ensuring stable operation of ultra-precise micro and nanoresonators) or to increase it (and enhancing in this manner the sensitivity of chemical and biological resonant sensors). In this work we derive and use analytical mathematical expressions to model stochastic fluctuations of the mass adsorbed on the MEMS resonator (mass loading noise). We consider the case where the resonator surface incorporates two different types of binding sites and where non-negligible depletion of the adsorbate occurs in a closed resonator chamber. We arrive at a novel expression for the power spectral density of mass loading noise in resonators and prove the necessity of its application in cases when resonators are exposed to low adsorbate concentrations. We use the novel approach presented here to calculate the resonator performance. In this way we ensure optimization of these MEMS devices and consequentially abatement of adsorption-desorption noise-caused degradation of their operation, both in the case of micro/nanoresonators and resonant sensors. This work is intended for a general use in the design, development and optimization of different MEMS systems based on mechanical resonators, ranging from the RF components to chemical and biological sensors.

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