共查询到20条相似文献,搜索用时 203 毫秒
1.
This paper describes a magnetically actuated cantilever with dual spring (cantilevered actuator and torsional cantilever) for a high-speed imaging of atomic force microscopy (AFM). A fabricated cantilever beam with a high resonant frequency is successfully actuated by electromagnetic force. A planar coil is placed on the free end of the cantilever beam and embedded in a groove formed on the silicon cantilever to get a large deflection. Static and dynamic mechanical characteristics of the fabricated probes have been measured. The experimental results of the mechanical properties are compared with the calculation results obtained from a finite element method. When flowing a current of ±10 mA, a static deflection of ±2 can be achieved by a cantilever with a length of 400 μm. The scanning speed of AFM is increased up to 1 mm/s by actuating the high resonant frequency cantilever in constant force mode 相似文献
2.
The performance of novel cantilever-based sensors approaches the limit posed by thermo-mechanical fluctuations, which is the currently accepted fundamental detection barrier for micro- and nanomechanical sensors. At the same time, the sensitivity of a high-level measurement techniques used for readout of the cantilever displacement nears the value of 10?14 m/Hz½. However, the thermo-mechanical noise of some cantilever sensors based on bimaterial structures is considerably higher than imposed by the fundamental limit. Moreover, the signal-to-noise ratio of some sensors based on contemporary MEMS technologies falls behind the characteristics of older types of mechanical sensors, fabricated using macroscopic production technologies. To investigate the cause of this situation, we perform a comparative analysis of the performance limits for two classes of cantilever sensors: the bimaterial cantilevers where the output signal is the transversal (lateral) displacement of the cantilever tip and the simple cantilever sensors where the signal is the longitudinal displacement along the cantilever axis. As a starting point of our analysis we established a correspondence between the parameters of a bimaterial cantilever and the simple cantilever. In a general case these two structures are not directly comparable, since the deformation of the bimaterial cantilever depends on 14 variables, while the longitudinal elongation of the simple cantilever depends on seven parameters only. However, under certain conditions analyzed in this paper a partial correspondence between the parameters of these two structures can be established. Our analysis shows that in certain applications a cantilever with longitudinal elongation has potentially better performance than the corresponding bimaterial element. 相似文献
3.
Latching micromagnetic optical switch 总被引:1,自引:0,他引:1
Zhilin Huang Jun Shen 《Journal of microelectromechanical systems》2006,15(1):16-23
In this paper, we report a new type of latching micromagnetic optical switch. The key component of this optical switch is a cantilever made of soft magnetic material with a reflective surface serving as a mirror. The cantilever has two stable positions, therefore two stable states for the device, with presence of an external magnetic field. Input optical signal to the device is switched selectively to one of the two output ports when the device transitions between the two states upon short electromagnetic actuations. The optical switch is bistable because the cantilever has a tendency to align with the external magnetic field, and the torque to align the cantilever can be bidirectional depending on the angle between the cantilever and the magnetic field. Switching between the two stable states is accomplished by momentarily changing the direction and/or the magnitude of the cantilever's magnetization by passing a short current pulse through a planar coil underneath the cantilever. In either of its stable state, the cantilever is held in position by the combined influence of the static external magnetic field and mechanical force, such as from a physical stopper or a mechanical torque produced by the torsion flexures supporting the cantilever. Stable vertical position for the cantilever is obtained by using a tilted external magnetic field. When the cantilever mirror is at this UP state, light is reflected to the desired output port. Large angle deflection and bistable latching operations have been demonstrated. The measured mechanical switching speed between the two states of the prototype is 3.2 ms. Optical insertion loss is -4 dB, and the energy consumption is 44 mJ for each switching event. 相似文献
4.
In this paper, flutter and divergence instabilities of a cantilever, a clamped–clamped, and a cantilever with intermediate
simply-support microbeam sandwiched by piezoelectric layers have been studied. By presenting a mathematical formulation and
numerical solution, critical piezoelectric force for avoiding of the instability in a cantilever microbeam has been calculated
and validated by known buckling capacity of Beck column. By applying a similar mathematical analysis it has been introduced
a critical piezoelectric voltage for a clamped–clamped microbeam. It has been shown that for cantilever microbeams, increasing
of the follower piezoelectric force leads to: first flutter and then divergence instabilities whereas in the clamped–clamped
microbeams only divergence instability can be occurred. Also effects of the intermediate simply support position on the critical
piezoelectric voltage of a cantilever microbeam have been investigated. It has been shown that for case when the intermediate
simply support is near to the fixed end of the cantilever increasing of the follower piezoelectric force leads to flutter
instability but for case when the intermediate simply support is near to the free end of the cantilever it leads to divergence
instability. 相似文献
5.
In the scanning probe microscopy-based microplasma etching system proposed by our group, the microcantilever probe integrated
with microplasma device is a multilayered structure. However, the thin film residual stress generated by microfabrication
process may cause undesirable bending deformation of the cantilever. In order to predict and minimize the stress-induced deformation
in the cantilever design, we experimentally measure and calculate each thin film stress of the cantilever based on Stoney
equation. Then the stress-induced bending deformation of the cantilever is simulated by finite element simulation. By adjusting
the thickness of reserved silicon layer of the cantilever, the deflection can be minimized to <5 μm for a 750 μm-length cantilever.
Finally the microcantilever probes with different thickness of reserved silicon layer are successfully fabricated by MEMS
process. The bending deformation of actual fabricated cantilevers agree well with simulation results, which verifies the feasibility
of the cantilever structural design. The results of this paper may lay a foundation for further scanning plasma maskless etching. 相似文献
6.
This paper investigates the swelling mechanics of polymer capture layers integrated into piezoresistive cantilever biochemical
sensors. A finite element model investigates mechanical deformations in a polymer layer affixed to a silicon microcantilever.
The polymer swells during analyte absorption, inducing deformations in the silicon cantilever which are sensed by a piezoresistive
sensor integrated into the cantilever. The highest sensitivity is predicted for short and wide cantilevers that are coated
with stiff polymer whose thickness is twice that of the cantilever. While the polymer swelling induces the deformations, the
silicon carries most of the load. When portions of the silicon beam are removed to introduce stress concentrations, the system
sensitivity can increase by 18% compared to the cantilever without stress concentrations. This study of stress distributions
in the cantilever system allows sensor optimization that considers the full 3D effects of polymer swelling mechanics. 相似文献
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8.
Acute angles formed in the underlying silicon during anisotropic etching to free silicon dioxide cantilever beams are found to be the point of maximum stress during etch. Consequently, failures of the cantilever structure originate at these locations. The origin of this stress concentration is due to mechanical loading of the cantilever during etch, and this loading effect is smaller for shorter or narrower cantilevers. Finite element modelling of a partially etched cantilever microstructure, as used to predict the location of maximum stress, as well as the probable vector direction failures, will follow. Cantilevers free of etch-induced failure are fabricated by isotropic etching and by the modification of etch geometry through the addition of ribbed segments to the cantilever. 相似文献
9.
Park K. Jungchul Lee Zhang Z.M. King W.P. 《Journal of microelectromechanical systems》2007,16(2):213-222
This paper investigates the electrical and thermal response of the heated atomic force microscope (AFM) cantilevers in the frequency range from 10 Hz to 1 MHz. Spectrum analysis of the cantilever voltage response to periodic heating distinguishes different thermal behaviors of the cantilever in the frequency domain: the cantilever voltage at low frequencies is modulated by higher-order harmonics, and at high frequencies it oscillates with 1-omega only. A simple model facilitates the understanding of complicated electrical and thermal behaviors in the cantilever, thus, it is possible to determine the cantilever temperature. The calculation predicts that temperature oscillation is restricted to the heater region when the cantilever is operated at about 10 kHz, suggesting that the periodic-heating operation of the cantilever may be employed for highly sensitive thermal metrology 相似文献
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11.
Simone Lee T. Mitch Wallis John Moreland Pavel Kabos Y. C. Lee 《Journal of microelectromechanical systems》2007,16(1):78-86
Multimaterial, microelectromechanical systems-based cantilever probes were developed for high-frequency magnetic field imaging. The basic configuration of the probe consists of a cantilever beam fabricated using surface micromachining and bulk micromachining techniques with dielectric silicon nitride and silicon oxide materials on a silicon wafer. A gold patterned metallization at the tip of the cantilever provides a source of eddy current heating due to the perpendicular component of the high-frequency magnetic field. This thermally absorbed power is converted to mechanical deflection by a multimaterial trilayer cantilever system. The deflection is measured with a beam-bounce optical technique employed in atomic force microscopy systems. We discuss the modeling, design, fabrication, and characterization of these field imaging probes 相似文献
12.
Chia-Yen Lee Chih-Yung Wen Hui-Hsiung Hou Ruey-Jen Yang Chien-Hsiung Tsai Lung-Ming Fu 《Microfluidics and nanofluidics》2009,6(3):363-371
This study designs and characterizes a novel MEMS-based flow-rate micro-sensor consisting of a platinum resistor deposited
on a silicon nitride-coated silicon cantilever beam. Due to the difference between the thermal conductivities of the silicon
nitride film and the silicon beam, the tip of the cantilever structure bends slightly in the upward direction. As air travels
across the upper surface of the sensor, it interferes with the curved tip and displaces the beam in either the upward or the
downward direction. The resulting change in the resistor signal is then used to calculate the velocity of the air. A flow-direction
micro-sensor is constructed by arranging eight cantilever structures on an octagonal platform. Each cantilever is separated
from its neighbors by a tapered baffle plate connected to a central octagonal pillar designed to attenuate the aerodynamic
force acting on the cantilever beams. By measuring the resistor signals of each of the cantilever beams, the micro-sensor
is capable of measuring both the flow rate and the flow direction of the air passing over the sensor. A numerical investigation
is performed to examine the effects of the pillar height and pillar-to-tip gap on the airflow distribution, the pressure distribution,
the bending moment acting on each beam, and the sensor sensitivity. The results show that the optimum sensor performance is
obtained using a pillar height of 0.75 mm and a pillar-to-tip gap of 5 mm. Moreover, the sensitivity of the octagonal sensing
platform is found to be approximately 90% that of a single cantilever beam. 相似文献
13.
Huicong Liu Cho Jui Tay Chenggen Quan Takeshi Kobayashi Chengkuo Lee 《Microsystem Technologies》2011,17(12):1747-1754
We propose a MEMS piezoelectric energy harvester with a wide operating frequency range by incorporating a high-frequency piezoelectric cantilever and a metal base as the top and bottom stoppers with a low-frequency piezoelectric cantilever. Frequency up-conversion of the piezoelectric energy harvester is realized when the low-frequency piezoelectric cantilever impacts and scrapes through the high-frequency piezoelectric cantilever. For an input acceleration of 0.6?g, with top and bottom stopper distances of 0.75 and 1.1?mm, respectively, the operating frequency ranges from 33 to 43?Hz. The output voltage and power up to 95?mV and 94 nW can be achieved. Experimental results indicate that the frequency up-conversion mechanism significantly improves the effective power. 相似文献
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15.
以TC4钛合金均质材料悬臂薄板为研究对象.基于经典板壳理论,通过Rayleigh-Ritz法,根据悬臂板边界条件预设模态函数,求得包括全局、局部的函数型几何缺陷的悬臂板的前四阶固有频率.探究了悬臂板的缺陷类型、尺寸、位置等多种因素对自由振动的影响. 相似文献
16.
A trapezoidal cantilever density sensor based on MEMS technology 总被引:1,自引:0,他引:1
Li-bo Zhao Long-qi Xu Gui-ming Zhang Yu-long Zhao Xiao-po Wang Zhi-gang Liu Zhuang-de Jiang 《浙江大学学报:C卷英文版》2013,14(4):274-278
A trapezoidal cantilever density sensor is developed based on micro-electro-mechanical systems (MEMS) technology. The sensor measures fluid density through the relationship between the density and the resonant frequency of the cantilever immersed in the fluid. To improve the sensitivity of the sensor, the modal and harmonic response analyses of trapezoidal and rectangular cantilevers are simulated by ANSYS software. The higher the resonant frequency of the cantilever immersed in the fluid, the higher the sensitivity of the sensor; the higher the resonant strain value, the easier the detection of the output signal of the sensor. Based on the results of simulation, the trapezoidal cantilever is selected to measure the densities of dimethyl silicone and toluene at the temperature ranges of 30 to 55 °C and 26 to 34 °C, respectively. Experimental results show that the trapezoidal cantilever density sensor has a good performance. 相似文献
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18.
采用Timoshenko梁修正理论研究了有梯度界面层双材料梁的振动问题,利用静力方程确定了有梯度界面层双材料梁的中性轴位置,在此基础上应用Timoshenko梁修正理论建立了有梯度界面层双材料梁的振动方程,求得其自振频率表达式及其在简谐荷载作用下强迫振动的解析解.讨论分析了梯度界面层高度等因素对有梯度界面层双材料梁的振动影响,并用有限元法验证了Timoshenko梁修正理论.通过实例计算,得到了梯度界面层高度等因素对有梯度界面层双材料梁振动特性有较大影响的结论. 相似文献
19.
We demonstrate the feasibility of a powder blasting micro-erosion process for the micromachining of accelerometer devices in glass. Using high-speed abrasive microparticles and a metal contact mask, we structure millimeter-size cantilever beams from simple glass slides. By metalizing one side of the glass substrate, we demonstrate both capacitive and piezoresistive/strain gauge detection of the vibrating cantilever mass and measure the frequency response of mechanically excited cantilever beams. We think that our approach opens new perspectives for manufacture of inertial sensing devices in a technology alternative to Si 相似文献
20.
This paper presents a novel cantilever-type MEMS variable capacitor with high tuning ratio. In previous works, the cantilever is used as a switch but in our design, it is applied as a variable capacitor. For increasing the maximum achievable capacitance of the cantilever, the suspended capacitive plate should be moved as parallel with fixed plate. The parallel movement can be obtained using the novel structure which utilized two additional lateral beams. Also to overcome the pull-in phenomenon in new structure, the different membrane thickness technique is used. The novelty of our design is adding the lateral beams to make parallel movement of the suspended plate to increase the variable capacitor of the cantilever. The new device is designed on a thick silicon substrate with a thin poly silicon membrane. The results show the tuning range of tunable capacitor with initial capacitance of 560.1 fF can be improved from 6:1 for conventional cantilever to 22.5:1 for the new cantilever. In other words the capacitance tuning range increased three times. 相似文献