In micro-electrochemical machining(μECM), material dissolution takes place at very close vicinity of tool electrode due to localization of electric field. Controlling the gap between tool electrode and workpiece is t...In micro-electrochemical machining(μECM), material dissolution takes place at very close vicinity of tool electrode due to localization of electric field. Controlling the gap between tool electrode and workpiece is the key to μECM. Therefore, a new method is proposed to solve a variety of problems in small gap control. In the present context, experiments were carried out with an indigenously developed setup to fabricate cylindrical arrays. During the machining process, the flat electrode bends due to electrostatic force in pulse on-time, which self-adaptively narrows the gap between the electrode and the workpiece. The workpiece material will be removed once the gap meets the processing condition. Therefore, this method has advantages of reducing dependence on high precision machine tools and of avoiding complex servo control. The flat electrode quickly restores to its original condition when it is in pulse off-time, making the gap much larger than that in traditional electrochemical machining(ECM). The large gap benefits debris removing, which improves the machining accuracy. The influence of different experimental parameters on accuracy and efficiency during the machining process has been investigated. It is observed that with the increase in applied voltage or concentration of electrolyte, the material removal rate and the process gap both increase. The detailed analysis of the experimental results is described in this paper.展开更多
In this paper, the effect of van der Waals （vdW） force on the pull-in behavior of electrostatically actuated nano/micromirrors is investigated. First, the minimum po- tential energy principle is utilized to find the...In this paper, the effect of van der Waals （vdW） force on the pull-in behavior of electrostatically actuated nano/micromirrors is investigated. First, the minimum po- tential energy principle is utilized to find the equation gov- erning the static behavior of nano/micromirror under electro- static and vdW forces. Then, the stability of static equilib- rium points is analyzed using the energy method. It is found that when there exist two equilibrium points, the smaller one is stable and the larger one is unstable. The effects of dif- ferent design parameters on the mirror＇s pull-in angle and pull-in voltage are studied and it is found that vdW force can considerably reduce the stability limit of the mirror. At the end, the nonlinear equilibrium equation is solved numer- ically and analytically using homotopy perturbation method （HPM）. It is observed that a sixth order perturbation approx- imation can precisely model the mirror＇s behavior. The re- suits of this paper can be used for stable operation design and safe fabrication of torsional nano/micro actuators.展开更多
We present a new analytical model for electrostatically actuated microbeams to explore the size effect by using the modified couple stress theory and the minimum total potential energy principle. A material length sca...We present a new analytical model for electrostatically actuated microbeams to explore the size effect by using the modified couple stress theory and the minimum total potential energy principle. A material length scale parameter is introduced to represent the size-dependent characteristics of microbeams. This model also accounts for the nonlinearities associated with the mid-plane stretching force and the electrostatical force. Numerical analysis for microbeams with clamped-clamped and cantilevered conditions has been performed. It is found that the intensity of size effect is closely associated with the thickness of the microbeam,and smaller beam thickness displays stronger size effect and hence yields smaller deffection and larger pull-in voltage. When the beam thickness is comparable to the material length scale parameter,the size effect is significant and the present theoretical model including the material length scale parameter is adequate for predicting the static behavior of microbeam-based MEMS.展开更多
Nonlinear spring characteristics of the tense torsion bar in the gap-closing type electrostatic micromirror are examined. The macro model is introduced for the experimental study. The tension applied in the torsion ba...Nonlinear spring characteristics of the tense torsion bar in the gap-closing type electrostatic micromirror are examined. The macro model is introduced for the experimental study. The tension applied in the torsion bar is well controlled using the electromagnetic attraction. This controllability is suited for clearing the nonlinear nature. The tension is confirmed to have the effect to widen the controllable angle range of the mirror suppressing the pull-in. The pull-in angle is observed to increases to about 74% of the mechanical limit angle at the tension of 0,96 N. This is significantly larger than 44% of the case with the linear spring. The larger resonant frequency is maintained. The hardening of the spring can keep the balance with the electrostatic force over the limit of the linear spring. The observed features are explained reasonably with the combination of twisting and bending displacements of the torsion bar.展开更多
This paper reports on the design, fabrication,and performance of a high-reflectivity large-rotation mirror array for MEMS （micro-electro-mechanical system） 16 × 16 optical switches. The mirror in the array can ...This paper reports on the design, fabrication,and performance of a high-reflectivity large-rotation mirror array for MEMS （micro-electro-mechanical system） 16 × 16 optical switches. The mirror in the array can enlarge its rotation an- gles up to 90° and keep a steady state to steer the optical signal. According to the large-rotation behavior, an electro- mechanical model of the mirror is presented. By monolithic integration of fiber grooves and mirrors fabricated by a sur- face and bulk hybrid micromachining process, the coarse passive alignment of fiber-mirror-fiber can be achieved. The re- flectivity of the mirror is measured to be 93.1% ~96.3%. The switches demonstrate that the smallest fiber-mirror-fiber insertion loss is 2. ldB using OptiFocusTM collimating lensed fibers. Moreover,only about ＋- 0.01dB oscillating amplitude of insertion loss is provoked after the device is tested for 15min for 5-90Hz in the vertical vibration amplitude of 3mm.展开更多
A delayed position feedback control is applied on DC of a typical MEMS resonator actuated by electrostatic forces voltage source for suppressing chaos A theoretical necessary condition for chaotic oscillation of the c...A delayed position feedback control is applied on DC of a typical MEMS resonator actuated by electrostatic forces voltage source for suppressing chaos A theoretical necessary condition for chaotic oscillation of the controlled system is presented. Numerical results and the analytical prediction reveal the evolution of dynamical behavior of the system with AC voltage amplitude and the control effect of delayed feedback on reducing chaos of the system. It shows that the delayed feedback control is effective on suppressing chaos of the micro mechanical resonator.展开更多
Hydraulic electrostatic actuators have become a research hotspot for their inherent flexibility and safety of human-machine interaction.This paper aims to combine the characteristics of dielectric elastomers and fluid...Hydraulic electrostatic actuators have become a research hotspot for their inherent flexibility and safety of human-machine interaction.This paper aims to combine the characteristics of dielectric elastomers and fluid actuators,enhancing the dielectric constant and breakdown field strength by modifying Al_(2)O_(3)on the surface of nanostructured BaTiO3 and in order to develop a hydraulic electrostatic actuator with silicone rubber as the matrix material.Single-factor experiments were firstly conducted to confirm the range of three factors affecting the actuation strain of the actuator:BaTiO_(3)@Al_(2)O_(3)content,thickness of the silicone rubber elastomer film,and pre-stretching ratio coefficient.The response surface methodology was used to study the interactive influence of the above three influencing factors on the actuation strain.It was obtained that A has an insignificant influence on the actuation strain,AB has a significant influence on the actuation strain,and B,C,AC,and BC have a highly influence on the actuation strain.Maximizing actuation strain as the optimization objective yielded the combination results of each factor:BaTiO_(3)@Al_(2)O_(3)content of 2.57%,thickness of 0.60 mm,and pre-stretching ratio coefficient of 2.50.Actuation strain tests were conducted with optimized parameters under no-load.The experimental results of the actuation strain test show that the relative error between the test value and the model prediction value of 16.47%is less than 5%,and the optimization model results are reliable.The optimized hydraulic electrostatic actuator was tested for actuation strain and electrical performance under different loads.The experiment showed that the maximum actuation strain of the hydraulic electrostatic actuator was 17.20%under a load of 100 g.The critical breakdown current of the actuator ranged from 115μA to 130μA,and the maximum electromechanical conversion efficiency of the actuator under different loads was 67.93%.Finally,a joint actuating device was developed based on the structure of the actuator,amplifying the output displacement of the actuator to 30 mm,and the linear displacement of the soft electro-fluid actuator can be converted into a 20°rotation angle through the gear steering mechanism,thus validating the effectiveness of the hydraulic electrostatic actuator.展开更多
Microelectromechanical system(MEMS)grating modulators enable versatile beam steering functions through the electrostatic actuation of movable ribbons.These modulators operate at ultrahigh frequencies in the hundred kH...Microelectromechanical system(MEMS)grating modulators enable versatile beam steering functions through the electrostatic actuation of movable ribbons.These modulators operate at ultrahigh frequencies in the hundred kHz range,and their micromirror-free configuration simplifies the fabrication process and reduces costs compared to micromirror-based modulators.However,these modulators are limited in their optical efficiency and aperture.Here,we present a MEMS grating modulator with a notably extendable aperture and a high optical efficiency that benefits from the adoption of a tunable sinusoidal grating.Instead of end-constrained movable ribbons,we constrain the MEMS grating modulator through broadside-constrained continuous ribbons.The end-free grating enables improved scalability along the ribbons,and the continuous sinusoidal surface of the grating allows an increased fill factor.As an example,we experimentally demonstrate a MEMS grating modulator with a large-scale aperture of 30×30 mm and an optical efficiency of up to 90%.The modulation depth enables intensity modulation across a broad wavelength range from 635 to 1700 nm.The experimental results demonstrate that the reported modulator has a mechanical settling time of 1.1μs and an extinction ratio of over 20 dB.Furthermore,it offers a dynamic modulation contrast of over 95%within a 250 kHz operating frequency and achieves full modulation within a field of view(FOV)of±30°.The reported MEMS grating modulator holds promise for application in high-speed light attenuation and modulating retroreflector free-space optical(MRR-FSO)communication systems.Our device also paves new ways for future high-speed,energyefficient,and cost-effective communication networks.展开更多
An integrated micro positioning xy-stage with a 2mm × 2mm-area shuttle is fabricated for application in nano- meter-scale operation and nanometric positioning precision. It is mainly composed of a silicon-based x...An integrated micro positioning xy-stage with a 2mm × 2mm-area shuttle is fabricated for application in nano- meter-scale operation and nanometric positioning precision. It is mainly composed of a silicon-based xy-stage,electrostatics comb actuator,and a displacement sensor based on a vertical sidewall surface piezoresistor. They are all in a monolithic chip and developed using double-sided bulk-micromachining technology. The high-aspect-ratio comb-driven xy-stage is achieved by deep reactive ion etching （DRIE） in both sides of the wafer. The detecting piezoresistor is located at the vertical sidewall surface of the detecting beam to improve the sensitivity and displacement resolution of the piezoresistive sensors using the DRIE technology combined with the ion implantation technology. The experimental results verify the integrated micro positioning xy-stage design including the micro xy-stage, electrostatics comb actuator,and the vertical sidewall surface piezoresistor technique. The sensitivity of the fabricated piezoresistive sensors is better than 1.17mV/μm without amplification and the linearity is better than 0. 814%. Under 30V driving voltage, a ± 10vm single-axis displacement is measured without crosstalk and the resonant frequency is measured at 983Hz in air.展开更多
The paper presents the size-dependant behaviors of the carbon nanotubes under electrostatic actuation using the modified couple stress theory and homotopy perturbation method.Due to the less accuracy of the classical ...The paper presents the size-dependant behaviors of the carbon nanotubes under electrostatic actuation using the modified couple stress theory and homotopy perturbation method.Due to the less accuracy of the classical elasticity theorems,the modified couple stress theory is applied in order to capture the size-dependant properties of the carbon nanotubes.Both of the static and dynamic behaviors under static DC and step DC voltages are discussed.The effects of various dimensions and boundary conditions on the deflection and pull-in voltages of the carbon nanotubes are to be investigated in detail via application of the homotopy perturbation method to solve the nonlinear governing equations semi-analytically.展开更多
A micromechanical optical switch driven by electrostatic was fabricated with (100) silicon and tilted 2.5° (111) silicon. The pull-in voltage is 13.2V, the insertion loss is less than 1.4dB, the crosstalk is less...A micromechanical optical switch driven by electrostatic was fabricated with (100) silicon and tilted 2.5° (111) silicon. The pull-in voltage is 13.2V, the insertion loss is less than 1.4dB, the crosstalk is less than -50 dB.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51105110,51475107)Shenzhen Basic Research Program(Grant No.JCYJ20170811160440239)
文摘In micro-electrochemical machining(μECM), material dissolution takes place at very close vicinity of tool electrode due to localization of electric field. Controlling the gap between tool electrode and workpiece is the key to μECM. Therefore, a new method is proposed to solve a variety of problems in small gap control. In the present context, experiments were carried out with an indigenously developed setup to fabricate cylindrical arrays. During the machining process, the flat electrode bends due to electrostatic force in pulse on-time, which self-adaptively narrows the gap between the electrode and the workpiece. The workpiece material will be removed once the gap meets the processing condition. Therefore, this method has advantages of reducing dependence on high precision machine tools and of avoiding complex servo control. The flat electrode quickly restores to its original condition when it is in pulse off-time, making the gap much larger than that in traditional electrochemical machining(ECM). The large gap benefits debris removing, which improves the machining accuracy. The influence of different experimental parameters on accuracy and efficiency during the machining process has been investigated. It is observed that with the increase in applied voltage or concentration of electrolyte, the material removal rate and the process gap both increase. The detailed analysis of the experimental results is described in this paper.
文摘In this paper, the effect of van der Waals （vdW） force on the pull-in behavior of electrostatically actuated nano/micromirrors is investigated. First, the minimum po- tential energy principle is utilized to find the equation gov- erning the static behavior of nano/micromirror under electro- static and vdW forces. Then, the stability of static equilib- rium points is analyzed using the energy method. It is found that when there exist two equilibrium points, the smaller one is stable and the larger one is unstable. The effects of dif- ferent design parameters on the mirror＇s pull-in angle and pull-in voltage are studied and it is found that vdW force can considerably reduce the stability limit of the mirror. At the end, the nonlinear equilibrium equation is solved numer- ically and analytically using homotopy perturbation method （HPM）. It is observed that a sixth order perturbation approx- imation can precisely model the mirror＇s behavior. The re- suits of this paper can be used for stable operation design and safe fabrication of torsional nano/micro actuators.
文摘We present a new analytical model for electrostatically actuated microbeams to explore the size effect by using the modified couple stress theory and the minimum total potential energy principle. A material length scale parameter is introduced to represent the size-dependent characteristics of microbeams. This model also accounts for the nonlinearities associated with the mid-plane stretching force and the electrostatical force. Numerical analysis for microbeams with clamped-clamped and cantilevered conditions has been performed. It is found that the intensity of size effect is closely associated with the thickness of the microbeam,and smaller beam thickness displays stronger size effect and hence yields smaller deffection and larger pull-in voltage. When the beam thickness is comparable to the material length scale parameter,the size effect is significant and the present theoretical model including the material length scale parameter is adequate for predicting the static behavior of microbeam-based MEMS.
文摘Nonlinear spring characteristics of the tense torsion bar in the gap-closing type electrostatic micromirror are examined. The macro model is introduced for the experimental study. The tension applied in the torsion bar is well controlled using the electromagnetic attraction. This controllability is suited for clearing the nonlinear nature. The tension is confirmed to have the effect to widen the controllable angle range of the mirror suppressing the pull-in. The pull-in angle is observed to increases to about 74% of the mechanical limit angle at the tension of 0,96 N. This is significantly larger than 44% of the case with the linear spring. The larger resonant frequency is maintained. The hardening of the spring can keep the balance with the electrostatic force over the limit of the linear spring. The observed features are explained reasonably with the combination of twisting and bending displacements of the torsion bar.
文摘This paper reports on the design, fabrication,and performance of a high-reflectivity large-rotation mirror array for MEMS （micro-electro-mechanical system） 16 × 16 optical switches. The mirror in the array can enlarge its rotation an- gles up to 90° and keep a steady state to steer the optical signal. According to the large-rotation behavior, an electro- mechanical model of the mirror is presented. By monolithic integration of fiber grooves and mirrors fabricated by a sur- face and bulk hybrid micromachining process, the coarse passive alignment of fiber-mirror-fiber can be achieved. The re- flectivity of the mirror is measured to be 93.1% ~96.3%. The switches demonstrate that the smallest fiber-mirror-fiber insertion loss is 2. ldB using OptiFocusTM collimating lensed fibers. Moreover,only about ＋- 0.01dB oscillating amplitude of insertion loss is provoked after the device is tested for 15min for 5-90Hz in the vertical vibration amplitude of 3mm.
基金supported by the National Natural Science Foundation of China(10902071)"Chen Guang" Project of Shanghai Municipal Education Commission(11CG61)+1 种基金Leading Academic Discipline Project of Shanghai Institute of Technology(1020Q121001)Shanghai Leading Academic Discipline Project(J51501)
文摘A delayed position feedback control is applied on DC of a typical MEMS resonator actuated by electrostatic forces voltage source for suppressing chaos A theoretical necessary condition for chaotic oscillation of the controlled system is presented. Numerical results and the analytical prediction reveal the evolution of dynamical behavior of the system with AC voltage amplitude and the control effect of delayed feedback on reducing chaos of the system. It shows that the delayed feedback control is effective on suppressing chaos of the micro mechanical resonator.
基金supported by the National Natural Science Foundation of China[No.52375293]the Open Fund of Laboratory of Aerospace Servo Actuation and Transmission[No.LASAT-2021-05]+1 种基金the Open Fund of Key Laboratory of Advanced Technology for Small and Medium-sized UAVs[No.XCA22054-06]the Research Fund of State Key Laboratory of Mechanics and Control for Aerospace Structures(Nanjing University of Aeronautics and Astronautics)[Nos.1005-ZAG23011,1005-IZD2400217].
文摘Hydraulic electrostatic actuators have become a research hotspot for their inherent flexibility and safety of human-machine interaction.This paper aims to combine the characteristics of dielectric elastomers and fluid actuators,enhancing the dielectric constant and breakdown field strength by modifying Al_(2)O_(3)on the surface of nanostructured BaTiO3 and in order to develop a hydraulic electrostatic actuator with silicone rubber as the matrix material.Single-factor experiments were firstly conducted to confirm the range of three factors affecting the actuation strain of the actuator:BaTiO_(3)@Al_(2)O_(3)content,thickness of the silicone rubber elastomer film,and pre-stretching ratio coefficient.The response surface methodology was used to study the interactive influence of the above three influencing factors on the actuation strain.It was obtained that A has an insignificant influence on the actuation strain,AB has a significant influence on the actuation strain,and B,C,AC,and BC have a highly influence on the actuation strain.Maximizing actuation strain as the optimization objective yielded the combination results of each factor:BaTiO_(3)@Al_(2)O_(3)content of 2.57%,thickness of 0.60 mm,and pre-stretching ratio coefficient of 2.50.Actuation strain tests were conducted with optimized parameters under no-load.The experimental results of the actuation strain test show that the relative error between the test value and the model prediction value of 16.47%is less than 5%,and the optimization model results are reliable.The optimized hydraulic electrostatic actuator was tested for actuation strain and electrical performance under different loads.The experiment showed that the maximum actuation strain of the hydraulic electrostatic actuator was 17.20%under a load of 100 g.The critical breakdown current of the actuator ranged from 115μA to 130μA,and the maximum electromechanical conversion efficiency of the actuator under different loads was 67.93%.Finally,a joint actuating device was developed based on the structure of the actuator,amplifying the output displacement of the actuator to 30 mm,and the linear displacement of the soft electro-fluid actuator can be converted into a 20°rotation angle through the gear steering mechanism,thus validating the effectiveness of the hydraulic electrostatic actuator.
基金sponsored by the National Natural Science Foundation of China(Grant No.U21B2035,51575455,51175436,62105265,and 62475219)the Fundamental Research Funds for the Central Universities(G2023KY05104).
文摘Microelectromechanical system(MEMS)grating modulators enable versatile beam steering functions through the electrostatic actuation of movable ribbons.These modulators operate at ultrahigh frequencies in the hundred kHz range,and their micromirror-free configuration simplifies the fabrication process and reduces costs compared to micromirror-based modulators.However,these modulators are limited in their optical efficiency and aperture.Here,we present a MEMS grating modulator with a notably extendable aperture and a high optical efficiency that benefits from the adoption of a tunable sinusoidal grating.Instead of end-constrained movable ribbons,we constrain the MEMS grating modulator through broadside-constrained continuous ribbons.The end-free grating enables improved scalability along the ribbons,and the continuous sinusoidal surface of the grating allows an increased fill factor.As an example,we experimentally demonstrate a MEMS grating modulator with a large-scale aperture of 30×30 mm and an optical efficiency of up to 90%.The modulation depth enables intensity modulation across a broad wavelength range from 635 to 1700 nm.The experimental results demonstrate that the reported modulator has a mechanical settling time of 1.1μs and an extinction ratio of over 20 dB.Furthermore,it offers a dynamic modulation contrast of over 95%within a 250 kHz operating frequency and achieves full modulation within a field of view(FOV)of±30°.The reported MEMS grating modulator holds promise for application in high-speed light attenuation and modulating retroreflector free-space optical(MRR-FSO)communication systems.Our device also paves new ways for future high-speed,energyefficient,and cost-effective communication networks.
文摘An integrated micro positioning xy-stage with a 2mm × 2mm-area shuttle is fabricated for application in nano- meter-scale operation and nanometric positioning precision. It is mainly composed of a silicon-based xy-stage,electrostatics comb actuator,and a displacement sensor based on a vertical sidewall surface piezoresistor. They are all in a monolithic chip and developed using double-sided bulk-micromachining technology. The high-aspect-ratio comb-driven xy-stage is achieved by deep reactive ion etching （DRIE） in both sides of the wafer. The detecting piezoresistor is located at the vertical sidewall surface of the detecting beam to improve the sensitivity and displacement resolution of the piezoresistive sensors using the DRIE technology combined with the ion implantation technology. The experimental results verify the integrated micro positioning xy-stage design including the micro xy-stage, electrostatics comb actuator,and the vertical sidewall surface piezoresistor technique. The sensitivity of the fabricated piezoresistive sensors is better than 1.17mV/μm without amplification and the linearity is better than 0. 814%. Under 30V driving voltage, a ± 10vm single-axis displacement is measured without crosstalk and the resonant frequency is measured at 983Hz in air.
文摘The paper presents the size-dependant behaviors of the carbon nanotubes under electrostatic actuation using the modified couple stress theory and homotopy perturbation method.Due to the less accuracy of the classical elasticity theorems,the modified couple stress theory is applied in order to capture the size-dependant properties of the carbon nanotubes.Both of the static and dynamic behaviors under static DC and step DC voltages are discussed.The effects of various dimensions and boundary conditions on the deflection and pull-in voltages of the carbon nanotubes are to be investigated in detail via application of the homotopy perturbation method to solve the nonlinear governing equations semi-analytically.
文摘A micromechanical optical switch driven by electrostatic was fabricated with (100) silicon and tilted 2.5° (111) silicon. The pull-in voltage is 13.2V, the insertion loss is less than 1.4dB, the crosstalk is less than -50 dB.
