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Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 559
Author(s):  
Gabriel Barrientos ◽  
Giacomo Clementi ◽  
Carlo Trigona ◽  
Merieme Ouhabaz ◽  
Ludovic Gauthier-Manuel ◽  
...  

In this paper, we present integrated lead-free energy converters based on a suitable MEMS fabrication process with an embedded layer of LiNbO3. The fabrication technology has been developed to realize micromachined self-generating transducers to convert kinetic energy into electrical energy. The process proposed presents several interesting features with the possibility of realizing smaller scale devices, integrated systems, miniaturized mechanical and electromechanical sensors, and transducers with an active layer used as the main conversion element. When the system is fabricated in the typical cantilever configuration, it can produce a peak-to-peak open-circuit output voltage of 0.208 V, due to flexural deformation, and a power density of 1.9 nW·mm−3·g−2 at resonance, with values of acceleration and frequency of 2.4 g and 4096 Hz, respectively. The electromechanical transduction capability is exploited for sensing and power generation/energy harvesting applications. Theoretical considerations, simulations, numerical analyses, and experiments are presented to show the proposed LiNbO3-based MEMS fabrication process suitability. This paper presents substantial contributions to the state-of-the-art, proposing an integral solution regarding the design, modelling, simulation, realization, and characterization of a novel transducer.


2022 ◽  
Vol 20 (1) ◽  
pp. 108-116
Author(s):  
Monico Linares Aranda ◽  
Luis Hernandez Martinez ◽  
Javier De la Hidalga Wade

Author(s):  
Zhenxi Liu ◽  
Jiamin Chen ◽  
Wuhao Yang ◽  
Tianyi Zheng ◽  
Qifeng Jiao ◽  
...  

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.


Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1374
Author(s):  
Giorgio De Pasquale

Recently, additive manufacturing (AM) processes applied to the micrometer range are subjected to intense development motivated by the influence of the consolidated methods for the macroscale and by the attraction for digital design and freeform fabrication. The integration of AM with the other steps of conventional micro-electro-mechanical systems (MEMS) fabrication processes is still in progress and, furthermore, the development of dedicated design methods for this field is under development. The large variety of AM processes and materials is leading to an abundance of documentation about process attempts, setup details, and case studies. However, the fast and multi-technological development of AM methods for microstructures will require organized analysis of the specific and comparative advantages, constraints, and limitations of the processes. The goal of this paper is to provide an up-to-date overall view on the AM processes at the microscale and also to organize and disambiguate the related performances, capabilities, and resolutions.


Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1261
Author(s):  
Young Chan Choi ◽  
June Soo Kim ◽  
Soon Yeol Kwon ◽  
Seong Ho Kong

In this paper we report on the improvement of performance by minimizing scallop size through deep reactive-ion etching (DRIE) of rotors in micro-wind turbines based on micro-electro-mechanical systems (MEMS) technology. The surface profile of an MEMS rotor can be controlled by modifying the scallop size of the DRIE surface through changing the process recipe. The fabrication of a planar disk-type MEMS rotor through the MEMS fabrication process was carried out, and for the comparison of the improvements in the performance of each rotor, RPM testing and open circuit output voltage experiments of stators and permanent magnets were performed. We found that the smooth etching profile with a minimized scallop size formed using DRIE results in improved rotation properties in MEMS-based wind turbine rotors.


Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1072
Author(s):  
Sergio Sapienza ◽  
Matteo Ferri ◽  
Luca Belsito ◽  
Diego Marini ◽  
Marcin Zielinski ◽  
...  

3C-SiC is an emerging material for MEMS systems thanks to its outstanding mechanical properties (high Young’s modulus and low density) that allow the device to be operated for a given geometry at higher frequency. The mechanical properties of this material depend strongly on the material quality, the defect density, and the stress. For this reason, the use of SiC in Si-based microelectromechanical system (MEMS) fabrication techniques has been very limited. In this work, the complete characterization of Young’s modulus and residual stress of monocrystalline 3C-SiC layers with different doping types grown on <100> and <111> oriented silicon substrates is reported, using a combination of resonance frequency of double clamped beams and strain gauge. In this way, both the residual stress and the residual strain can be measured independently, and Young’s modulus can be obtained by Hooke’s law. From these measurements, it has been observed that Young’s modulus depends on the thickness of the layer, the orientation, the doping, and the stress. Very good values of Young’s modulus were obtained in this work, even for very thin layers (thinner than 1 mm), and this can give the opportunity to realize very sensitive strain sensors.


2021 ◽  
pp. 160-167
Author(s):  
Paloma Rodríguez ◽  
Enrique Mancha Sánchez ◽  
Almudena Bravo ◽  
Cristina Nuevo-Gallardo ◽  
Inés Tejado ◽  
...  

Microrobotics is an emerging field of research with countless applications in industry, biology and medicine. Despite advances in the field, there are still considerable challenges including that of micrometer-scale robot manufacturing. The fabrication of microrobots benefits from advances in microelectromechanical systems (MEMS) manufacturing. This paper presents the equipment that forms the MEMS fabrication laboratory at Universidad de Extremadura (UEX), as well as examples of microrobot fabrication that have been carried out.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Hoa Thanh Le ◽  
Rubaiyet I. Haque ◽  
Ziwei Ouyang ◽  
Seung Woo Lee ◽  
Shelley I. Fried ◽  
...  

AbstractMEMS inductors are used in a wide range of applications in micro- and nanotechnology, including RF MEMS, sensors, power electronics, and Bio-MEMS. Fabrication technologies set the boundary conditions for inductor design and their electrical and mechanical performance. This review provides a comprehensive overview of state-of-the-art MEMS technologies for inductor fabrication, presents recent advances in 3D additive fabrication technologies, and discusses the challenges and opportunities of MEMS inductors for two emerging applications, namely, integrated power electronics and neurotechnologies. Among the four top-down MEMS fabrication approaches, 3D surface micromachining and through-substrate-via (TSV) fabrication technology have been intensively studied to fabricate 3D inductors such as solenoid and toroid in-substrate TSV inductors. While 3D inductors are preferred for their high-quality factor, high power density, and low parasitic capacitance, in-substrate TSV inductors offer an additional unique advantage for 3D system integration and efficient thermal dissipation. These features make in-substrate TSV inductors promising to achieve the ultimate goal of monolithically integrated power converters. From another perspective, 3D bottom-up additive techniques such as ice lithography have great potential for fabricating inductors with geometries and specifications that are very challenging to achieve with established MEMS technologies. Finally, we discuss inspiring and emerging research opportunities for MEMS inductors.


Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 892
Author(s):  
Jicong Zhao ◽  
Zheng Zhu ◽  
Haiyan Sun ◽  
Shitao Lv ◽  
Xingyu Wang ◽  
...  

This paper presents a micro-electro-mechanical systems (MEMS) processing technology for Aluminum Nitride (AlN) Lamb-wave resonators (LWRs). Two LWRs with different frequencies of 402.1 MHz and 2.097 GHz by varying the top interdigitated (IDT) periods were designed and fabricated. To avoid the shortcomings of the uncontrollable etching of inactive areas during the releasing process and to improve the fabrication yield, a thermal oxide layer was employed below the platted polysilicon sacrificial layer, which could define the miniaturized release cavities well. In addition, the bottom Mo electrode that was manufactured had a gentle inclination angle, which could contribute to the growth of the high-quality AlN piezoelectric layer above the Mo layer and effectively prevent the device from breaking. The measured results show that the IDT-floating resonators with 12 μm and 2 μm electrode periods exhibit a motional quality factor (Qm) as high as 4382 and 1633. The series resonant frequency (fs)·Qm values can reach as high as 1.76 × 1012 and 3.42 × 1012, respectively. Furthermore, Al is more suitable as the top IDT material of the AlN LWRs than Au, and can contribute to achieving an excellent electrical performances due to the smaller density, smaller thermo-elastic damping (TED), and larger acoustic impedance difference between Al and AlN.


Author(s):  
Sahar Jaddi ◽  
Jean-Pierre Raskin ◽  
Thomas Pardoen

Abstract An on-chip fracture mechanics method is extended to characterize subcritical crack growth in submicron freestanding films. The method relies on a self-actuated concept based on MEMS fabrication principles. The configuration consists of a notched specimen attached to actuator beams involving high internal stress. Upon release, a crack initiates at the notch, propagates, and arrests. Several improvements are worked out to limit the mode III component and to avoid crack kinking. The method is applied to subcritical crack growth in 140-nm-thick SiO2 films under different humidity conditions. The data reduction scheme relates crack growth rate to stress intensity factor. The static fracture toughness value is ~ 0.73 MPa $$\sqrt{\mathrm{m}}$$ m , with standard error of 0.01 MPa $$\sqrt{\mathrm{m}}$$ m and standard deviation of 0.17 MPa $$\sqrt{\mathrm{m}}.$$ m . Subcritical crack growth rates are much smaller than in bulk specimens. A major advantage is that many test samples can be simultaneously monitored while avoiding any external equipment. Graphic Abstract


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