The pull-in instability of a cantilever nano-actuator model incorporating the effects of the surface, the fringing field, and the Casimir attraction force is investigated. A new quartic polynomial is proposed as the s...The pull-in instability of a cantilever nano-actuator model incorporating the effects of the surface, the fringing field, and the Casimir attraction force is investigated. A new quartic polynomial is proposed as the shape function of the beam during the deflection, satisfying all of the four boundary values. The Gaussian quadrature rule is used to treat the involved integrations, and the design parameters are preserved in the evaluated formulas. The analytic expressions are derived for the tip deflection and pull-in parameters of the cantilever beam. The micro-electromechanical system (MEMS) cantilever actuators and freestanding nano-actuators are considered as two special cases. It is proved that the proposed method is convenient for the analyses of the effects of the surface, the Casimir force, and the fringing field on the pull-in parameters.展开更多
In this paper, a mathematical model is presented for studying thin film damping of the surrounding fluid in an in-plane oscillating micro-beam resonator. The proposed model for this study is made up of a clamped-clamp...In this paper, a mathematical model is presented for studying thin film damping of the surrounding fluid in an in-plane oscillating micro-beam resonator. The proposed model for this study is made up of a clamped-clamped micro-beam bound between two fixed layers. The microgap between the micro-beam and fixed layers is filled with air. As classical theories are not properly capable of predicting the size dependence behaviors of the micro-beam,and also behavior of micro-scale fluid media, hence in the presented model, equation of motion governing longitudinal displacement of the micro-beam has been extracted based on non-local elasticity theory. Furthermore, the fluid field has been modeled based on micro-polar theory. These coupled equations have been simplified using Newton-Laplace and continuity equations. After transforming to non-dimensional form and linearizing, the equations have been discretized and solved simultaneously using a Galerkin-based reduced order model. Considering slip boundary conditions and applying a complex frequency approach, the equivalent damping ratio and quality factor of the micro-beam resonator have been obtained. The obtained values for the quality factor have been compared to those based on classical theories. We have shown that applying non-classical theories underestimate the values of the quality factor obtained based on classical theo-ries. The effects of geometrical parameters of the micro-beam and micro-scale fluid field on the quality factor of the resonator have also been investigated.展开更多
At present,there are few technologies applied to in situ observation of seabed deformation,among which the micro-electromechanical accelerometer-array(hereinafter referred to as accelerometers array)is a very advantag...At present,there are few technologies applied to in situ observation of seabed deformation,among which the micro-electromechanical accelerometer-array(hereinafter referred to as accelerometers array)is a very advantageous measurement method,with both commercial products and successful application cases.However,the coupling effect between accelerometer-array and sur-rounding soil and the linkage effect of accelerometer-array itself during the deformation may influence the accuracy and reliability of the measurement data.A simulation test chamber was designed and processed,and four groups of simulation tests were carried out to explore the coupling effect and linkage effect of accelerometer-array in the soil with different degree of consolidation.The results show that the accelerometer-array and the soil coupled well,and the coupling effect is positively correlated with the degree of soil consoli-dation.The ratio of accumulative deviation to soil lateral deformation is high at the initial stage of deformation(0-50 mm)and reduced with the continuous increase of deformation(>100 mm).In the process of liquefied soil deformation,the linkage effect of accelerometer array can be ignored,and is negatively correlated with the degree of soil consolidation.A concept to improve the measurement accu-racy of accelerometer-array in different seafloor failure deformation modes is proposed.The research results provide references for the modification of accelerometer-array and the improvement for other flexible rod-shaped deformation sensors.展开更多
The virtual machine of code mechanism (VMCM) as a new concept for code mechanical solidification and verification is proposed and can be applied in MEMS (micro-electromechanical systems) security device for high c...The virtual machine of code mechanism (VMCM) as a new concept for code mechanical solidification and verification is proposed and can be applied in MEMS (micro-electromechanical systems) security device for high consequence systems. Based on a study of the running condition of physical code mechanism, VMCM's configuration, ternary encoding method, running action and logic are derived. The cases of multi-level code mechanism are designed and verified with the VMCM method, showing that the presented method is effective.展开更多
The output characteristics of micro-solar cell arrays are analyzed on the basis of a modified model in which the shunt resistance between cell lines results in current leakage.The modification mainly consists of addin...The output characteristics of micro-solar cell arrays are analyzed on the basis of a modified model in which the shunt resistance between cell lines results in current leakage.The modification mainly consists of adding a shunt resistor network to the traditional model.The obtained results agree well with the reported experimental results.The calculation results demonstrate that leakage current in substrate affects seriously the performance of GaAs micro-solar cell arrays.The performance of arrays can be improved by reducing the number of cells per line.In addition,at a certain level of integration,an appropriate space occupancy rate of the single cell is recommended for ensuring high open circuit voltages,and it is more appropriate to set the rates at 80%-90% through the calculation.展开更多
We analyze the effects of possible noise sources on a fence structure micromachined capacitive accelerometer system by modeling and simulation to improve its performance. Simulation results show that a mismatch betwee...We analyze the effects of possible noise sources on a fence structure micromachined capacitive accelerometer system by modeling and simulation to improve its performance. Simulation results show that a mismatch between the two initial sensing capacitors of the accelerometer or a mismatch between the two capacitance-voltage conversion circuits has a great effect on the output noise floor. When there is a serious mismatch, the noise induced by a sinusoidal carrier is the major noise source. When there is no or only a slight mismatch, the differential capacitance-voltage conversion circuits become the main noise source. The simulation results were validated by experiments and some effective approaches are proposed to improve the system resolution.展开更多
The simultaneous control of residual stress and resistivity of polysilicon thin films by adjusting the deposition parameters and annealing conditions is studied. In situ boron doped polysilicon thin films deposited at...The simultaneous control of residual stress and resistivity of polysilicon thin films by adjusting the deposition parameters and annealing conditions is studied. In situ boron doped polysilicon thin films deposited at 520 ℃ by low pressure chemical vapor deposition (LPCVD) are amorphous with relatively large compressive residual stress and high resistivity. Annealing the amorphous films in a temperature range of 600-800 ℃ gives polysilicon films nearly zero-stress and relatively low resistivity. The low residual stress and low resistivity make the polysilicon films attractive for potential applications in micro-electro-mechanical-systems (MEMS) devices, especially in high resonance frequency (high-f) and high quality factor (high-Q) MEMS resonators. In addition, polysilicon thin films deposited at 570 ℃ and those without the post annealing process have low resistivities of 2-5 mΩ·cm. These reported approaches avoid the high temperature annealing process (〉 1000 ℃), and the promising properties of these films make them suitable for high-Q and high-f MEMS devices.展开更多
基金supported by the National Natural Science Foundation of China(No.11201308)the Natural Science Foundation of Shanghai(No.14ZR1440800)the Innovation Program of the Shanghai Municipal Education Commission(No.14ZZ161)
文摘The pull-in instability of a cantilever nano-actuator model incorporating the effects of the surface, the fringing field, and the Casimir attraction force is investigated. A new quartic polynomial is proposed as the shape function of the beam during the deflection, satisfying all of the four boundary values. The Gaussian quadrature rule is used to treat the involved integrations, and the design parameters are preserved in the evaluated formulas. The analytic expressions are derived for the tip deflection and pull-in parameters of the cantilever beam. The micro-electromechanical system (MEMS) cantilever actuators and freestanding nano-actuators are considered as two special cases. It is proved that the proposed method is convenient for the analyses of the effects of the surface, the Casimir force, and the fringing field on the pull-in parameters.
文摘In this paper, a mathematical model is presented for studying thin film damping of the surrounding fluid in an in-plane oscillating micro-beam resonator. The proposed model for this study is made up of a clamped-clamped micro-beam bound between two fixed layers. The microgap between the micro-beam and fixed layers is filled with air. As classical theories are not properly capable of predicting the size dependence behaviors of the micro-beam,and also behavior of micro-scale fluid media, hence in the presented model, equation of motion governing longitudinal displacement of the micro-beam has been extracted based on non-local elasticity theory. Furthermore, the fluid field has been modeled based on micro-polar theory. These coupled equations have been simplified using Newton-Laplace and continuity equations. After transforming to non-dimensional form and linearizing, the equations have been discretized and solved simultaneously using a Galerkin-based reduced order model. Considering slip boundary conditions and applying a complex frequency approach, the equivalent damping ratio and quality factor of the micro-beam resonator have been obtained. The obtained values for the quality factor have been compared to those based on classical theories. We have shown that applying non-classical theories underestimate the values of the quality factor obtained based on classical theo-ries. The effects of geometrical parameters of the micro-beam and micro-scale fluid field on the quality factor of the resonator have also been investigated.
基金funded by the National Natural Science Foundation of China(Nos.42022052,42107207)the Shan-dong Provincial Natural Science Foundation(Nos.ZR2020QD067,ZR2020YQ29)the Postdoctoral Science Foundation of China(No.2019M662474).
文摘At present,there are few technologies applied to in situ observation of seabed deformation,among which the micro-electromechanical accelerometer-array(hereinafter referred to as accelerometers array)is a very advantageous measurement method,with both commercial products and successful application cases.However,the coupling effect between accelerometer-array and sur-rounding soil and the linkage effect of accelerometer-array itself during the deformation may influence the accuracy and reliability of the measurement data.A simulation test chamber was designed and processed,and four groups of simulation tests were carried out to explore the coupling effect and linkage effect of accelerometer-array in the soil with different degree of consolidation.The results show that the accelerometer-array and the soil coupled well,and the coupling effect is positively correlated with the degree of soil consoli-dation.The ratio of accumulative deviation to soil lateral deformation is high at the initial stage of deformation(0-50 mm)and reduced with the continuous increase of deformation(>100 mm).In the process of liquefied soil deformation,the linkage effect of accelerometer array can be ignored,and is negatively correlated with the degree of soil consolidation.A concept to improve the measurement accu-racy of accelerometer-array in different seafloor failure deformation modes is proposed.The research results provide references for the modification of accelerometer-array and the improvement for other flexible rod-shaped deformation sensors.
基金Project supported by High-Technology Research and Develop-ment Program of China (Grant No .863 -2003AA404210)
文摘The virtual machine of code mechanism (VMCM) as a new concept for code mechanical solidification and verification is proposed and can be applied in MEMS (micro-electromechanical systems) security device for high consequence systems. Based on a study of the running condition of physical code mechanism, VMCM's configuration, ternary encoding method, running action and logic are derived. The cases of multi-level code mechanism are designed and verified with the VMCM method, showing that the presented method is effective.
文摘The output characteristics of micro-solar cell arrays are analyzed on the basis of a modified model in which the shunt resistance between cell lines results in current leakage.The modification mainly consists of adding a shunt resistor network to the traditional model.The obtained results agree well with the reported experimental results.The calculation results demonstrate that leakage current in substrate affects seriously the performance of GaAs micro-solar cell arrays.The performance of arrays can be improved by reducing the number of cells per line.In addition,at a certain level of integration,an appropriate space occupancy rate of the single cell is recommended for ensuring high open circuit voltages,and it is more appropriate to set the rates at 80%-90% through the calculation.
基金Project (No. NCET-06-0514) supported by the Program for New Century Excellent Talents in University of China
文摘We analyze the effects of possible noise sources on a fence structure micromachined capacitive accelerometer system by modeling and simulation to improve its performance. Simulation results show that a mismatch between the two initial sensing capacitors of the accelerometer or a mismatch between the two capacitance-voltage conversion circuits has a great effect on the output noise floor. When there is a serious mismatch, the noise induced by a sinusoidal carrier is the major noise source. When there is no or only a slight mismatch, the differential capacitance-voltage conversion circuits become the main noise source. The simulation results were validated by experiments and some effective approaches are proposed to improve the system resolution.
基金supported by the National High Technology Research and Development Program of China(No.2007AA04Z322)the State Key Development Program for Basic Research of China (No.2009CB320305)the Chinese Academy of Sciences
文摘The simultaneous control of residual stress and resistivity of polysilicon thin films by adjusting the deposition parameters and annealing conditions is studied. In situ boron doped polysilicon thin films deposited at 520 ℃ by low pressure chemical vapor deposition (LPCVD) are amorphous with relatively large compressive residual stress and high resistivity. Annealing the amorphous films in a temperature range of 600-800 ℃ gives polysilicon films nearly zero-stress and relatively low resistivity. The low residual stress and low resistivity make the polysilicon films attractive for potential applications in micro-electro-mechanical-systems (MEMS) devices, especially in high resonance frequency (high-f) and high quality factor (high-Q) MEMS resonators. In addition, polysilicon thin films deposited at 570 ℃ and those without the post annealing process have low resistivities of 2-5 mΩ·cm. These reported approaches avoid the high temperature annealing process (〉 1000 ℃), and the promising properties of these films make them suitable for high-Q and high-f MEMS devices.