Electrothermal Microactuator Research Articles

Theoretical analysis for dynamic model of U-shaped electrothermal microactuator based on Chebyshev spectral method

Abstract This paper presents a largely and accurate analysis for dynamic model of U-shaped actuator that considers the material parameters dependent on temperature. The electro-thermal analysis for temperature distribution and thermo-mechanical analysis for deflection is carried out. The electro-thermal dynamic behaviour is described by piecewise one-dimensional (1D) heat transfer partial differential equations (PDE) for each beam of U-shaped actuator. A combination of Chebyshev spectral method for space domain and Euler forward difference method for time domain is used to solve these equations. The convergence test is first done to ensure the result convinced.

Additive manufacturing method of electrothermal 4D bimorph microactuator

Additive manufacturing method of electrothermal 4D bimorph microactuator

Improving displacement of silicon V-shaped electrothermal microactuator using platinum sputter deposition process

PurposeThis paper aims to propose a method to reduce the resistance of silicon-based V-shaped electrothermal microactuator (VEM) by applying a surface sputtering process.Design/methodology/approachFour VEM’s samples have been fabricated using traditional silicon on insulator (SOI)-Micro-electro-mechanical System (MEMS) technology, three of them are coated with a thin layer of platinum on the top surface by sputtering technique with different sputtered times and the other is original. The displacements of the VEM are calculated and simulated to evaluate the advantages of sputtering method.FindingsThe measured results show that the average resistance of the sputtered structures is approximately 1.16, 1.55 and 2.4 times lower than the non-sputtering sample corresponding to the sputtering time of 1.5, 3 and 6 min. Simulation results confirmed that the maximum displacement of the sputtered VEM is almost 1.45 times larger than non-sputtering one in the range of voltage from 8 to 20 V. The experimental displacements are also measured to validate the better performance of the sputtered samples.Originality/valueThe experimental results demonstrated the better displacement of the VEM structure after using the platinum sputtering process. The improvement can be considered and applied for enhancing displacement as well as decreasing the driving voltage of the other electrothermal microactuators like U- or Z-shaped structures while combining with the low-cost SOI-MEMS micromachining technology.

Analyzing and optimizing of electro-thermal MEMS micro-actuator performance by BFA algorithm

Analyzing and optimizing of electro-thermal MEMS micro-actuator performance by BFA algorithm

Improvement procedure of temperature field for electrothermal microgripper with parallel beam

This paper mainly studies the high-temperature problem of the electrothermal microgripper with a parallel beam (EMPB). Firstly, a temperature model based on the structure analysis was built. Then, a series of optimal designs of temperature field was conducted, which includes the S beam and the cooling beam at the bottom of the heated cantilever. Finally, the experimental sample of the gripper was made, and the temperature field was directly characterized by the microscopic thermal imaging equipment. The feasibility of the temperature optimization was verified by the microsphere gripper experiment. The result shows that the optimization scheme can reduce the temperature of the tip finger by 50–200 ℃, the substrate temperature by 30–80 ℃, and increase the tension of the gripper by 30~100%, which makes a better temperature field distribution of the electrothermal microgripper. The proposed optimization scheme could apply to the temperature control of the electrothermal micro-actuator of other materials or mechanisms.

Modeling of multiphysics coupling and performance analysis of Z-shaped electrothermal microactuator

Electrothermal microactuators have a very promising future in micro-electro-mechanical systems applications since they can generate large displacement and force with low actuating voltages and small device areas. In this paper, a temperature distribution and unload displacement model of a Z-shaped electrothermal microactuator is presented. In order to prove the accuracy of the model, finite element analysis (FEA) and experimental results are provided to make comparison. The results of temperature profile and unload displacement output, which are from the model calculation, FEA and experimental test, agree well with each other. It gives an indirect proof that the model is correct and FEA calculation is practicable. It can be shown that the shape of the actuator has no effect on the maximum temperature, and the unload displacement and output force depend on the beam length and inclined angle of the actuator.

Double-objective optimization of electro-thermal (E-T) micro-actuator for fiber switch

In this paper, a novel optimization method, in which composed of the genetic algorithm, particle swarm optimization (GA–PSO) and improved gradient descent algorithm, are used to conduct a double-objective optimization for the U-shaped actuator. In the procedure of optimization, two objectives, i.e. force and displacement, and four main sizes are utilized. Before, the deep reactive-ion etch (DRIE) technology is applied to the fabrication of the U-shaped actuator. When different voltages are applied on the actuator, the displacement obtained from numerical calculation always shows a good agreement with that from experiment by edge detection algorithm. Similar phenomenon can be also seen when an external force supplied by the nanoindentation system FemtoTools in the experiment is loaded on the actuator. Based on the validated simulation model of the U-shaped actuator, the improved gradient descent method ensures its displacement very close to 50 µm (target displacement) while the GA–PSO algorithm is used to maximize the output force. In this procedure, the hybrid optimization method implemented by Matlab is incorporated into ANSYS simulation. Preliminary analysis shows that the displacement and force of the particles in each iteration concentrate together with the iteration growing. Fine convergence, whose velocity only depends on the number of particle in the algorithm, is also found in each optimization. Furthermore, the optimized actuators have homologous value of the size variables. At 15 V voltage, the displacement and largest output force of the U-shaped actuator are 2 mN and 50.1 µm, respectively. Finally, an actuator with 30% improvement of the output force is obtained when the displacement condition is meet. According to the optimization result and further parametric scanning simulation analysis, the design range and fabrication error of the sizes of the U-shaped actuator are obtained.

Failure analysis of electro-thermal micro-actuator under effect of process error

Failure analysis of electro-thermal micro-actuator under effect of process error

Design and simulation of an out-of-plane electrothermal microactuator

Microactuators are one of the most important components in microelectromechanical systems (MEMS). Therefore, designing effective out-of-plane actuators has been in progress for the last decade. This paper presents a novel design of the microactuator with a double stepped beam structure for large out-of-plane deflection output applied to microvalves. The design and analysis of the out-of-plane microactuator are implemented by the finite element method. Silicon is selected as the material of the actuator and the beam motion is generated by the Joule heating effect. Compared to a single stepped beam design reported in the literature, the simulation results show that the proposed double-stepped beam structure can deliver a much larger out-of-plane deflection. Under an applied current of 15 mA, the maximum deflection of the double stepped beam is nearly seven times higher than that of the single stepped beam structure. In addition, the stress analysis indicates that the largest stress (1.46 GPa) induced in the beam is much smaller than the yield strength (7 GPa) of the selected silicon material.

Withdrawal Notice: Fabrication of Bidirectional Electrothermal Microactuator by Two-Photon Polymerization

The article has been withdrawn at the request of the authors of the journal Current Nanoscience. Bentham Science apologizes to the readers of the journal for any inconvenience this may cause. The Bentham Editorial Policy on Article Withdrawal can be found at https://benthamscience.com/editorial-policies-main.php Bentham Science Disclaimer: It is a condition of publication that manuscripts submitted to this journal have not been published and will not be simultaneously submitted or published elsewhere. Furthermore, any data, illustration, structure or table that has been published elsewhere must be reported, and copyright permission for reproduction must be obtained. Plagiarism is strictly forbidden, and by submit-ting the article for publication the authors agree that the publishers have the legal right to take appropriate action against the authors, if plagiarism or fabricated information is discovered. By submitting a manuscript, the authors agree that the copyright of their article is transferred to the publishers if and when the article is accepted for publication.

Effects of Sidewall Inclination on Performance of Electrothermal Micro-Actuator

As an important part of Micro-Electro-Mechanical systems (MEMS), micro-actuators have a direct impact on the performance of MEMS devices. This paper presents the effects of sidewall inclination of deep reactive ion etching (DRIE) on the performance of U-shaped electrothermal micro-actuators. The electrothermal micro-actuator models with sidewall inclination angles from -5° to 5° are simulated through finite element method (FEM) by ANSYS to study the influences on the output displacement and the highest node temperature. The simulation results show that electrothermal micro-actuator with larger sidewall inclination angle has more displacement deviation. In addition, larger voltage amplifies the deviation of displacement. The highest node temperature decreases with the increase of the sidewall inclination, and the deviation is small.

Design and fabrication of an electrothermal MEMS micro-actuator with 3D printing technology

This study presents the design and fabrication results of an electrothermal micro-electro-mechanical system (MEMS) actuator. Unlike traditional one-directional U-shaped actuators, this bi-directional electrothermal (BET) micro-actuator can produce displacements in two directions as a single device. The BET micro-actuator was fabricated using two-photon polymerization (2PP) and digital light processing (DLP) methods, which are 3D printing techniques. These methods have been compared to see the success of BET micro-actuator fabrication. The compound of these methods and the essential coefficients through the 3D printing operation were applied. Evaluation experiments have demonstrated that in both methods, the 3D printer can print materials smaller than 95.7 μm size features. Though the same design was used for the 2PP and DLP methods, the supporting structures were not produced with the 2PP. The BET micro-actuator was manufactured by removing the supports from the original design in the 2PP. The number of supports, the diameter, and height on the arms of the micro-actuator is 18, 4 μm, and 6 μm, respectively. Although 4 μm diameter supports could be produced with the DLP, it was not possible to produce them with 3D printing device based on 2PP. Besides, the DLP was found to be better than the 2PP for the manufacturing of asymmetrical support structures. The fabrication process has been carried out successfully by two methods. When the fabrication success is compared, the surface quality and fabrication speed of the micro-actuator fabricated with DLP is better than the 2PP. Presented results show the efficiency of the 3D printing technology and the simplicity of fabrication of the micro-actuator via 2PP and DLP. An experimental study was carried out to characterize the relationship between displacement and input voltage for the micro-actuator. Experimental results show that the displacement range of the micro-actuator is 8 μm with DLP, while 6 μm with 2PP.

Analysis of the dynamic behavior of a V-shaped electrothermal microactuator

This paper presents an accurate and complete analysis of the dynamic performance of a V-shaped microactuator. This multi-physical coupling analysis is split into two steps: the electro-thermal sub-model for temperature distribution and the thermo-elastic sub-model for displacement. For the electro-thermal sub-model, a combination of the Chebyshev spectral method and the improved Euler method is utilized to predict the thermal dynamic behavior, where a piecewise partial differential equation exists. This method is found to have conditional stability which is dependent on time steps and number of points. Although a one-dimensional geometric model is used in it, the obtained temperature profile hardly shows a difference over time compared with that from the finite element method where a three-dimensional geometric model is established. The method’s calculation time is also sharply reduced. According to the forced vibration theory, the thermo-elastic sub-model is rebuilt regardless of the damping term. When applied to different voltages, the displacement of the actuator at a steady state is validated by an experiment and an ANSYS simulation. Furthermore, the result of the transient displacement also shows a good agreement with the ANSYS simulation.

An Alternative Approach to Investigate V-Shaped Electrothermal Microactuators in Vacuum

In this work, we use a simplified version of Young’s solution for the steady-state Joule-heating, that uses temperature dependent thermal and electrical conductivities, to find the temperature and displacement behavior of a V-shaped electrothermal microactuator (ETMA) device. In order to test and validate our approach we performed FEM simulations and actually built an ETMA device by microfabrication. The experimental device displacement was measured in vacuum, with a scanning electron microscope. Our numerical results agree quite well with the FEM simulation and experimental results up to a displacement of (0.8 ± 0.2) $\mu \text{m}$ and applied current of 30 mA. Above 35 mA, an abrupt variation of the resistivity is observed followed by surface degradation at 50 mA and device melting at 52 mA. The validity of our approach is discussed of the device geometry and material parameters. [2019-0208]

Automated manipulation of zebrafish embryos using an electrothermal microgripper

We present the first report on automated micro-manipulation of zebrafish embryos using an electrothermally-actuated microgripper. A five-bar linkage compliant microgripper, driven by a V-shaped electrothermal micro-actuator, is designed based on topological optimization. The electrothermally-actuated microgripper is fabricated, tested, and then integrated into a robotic micromanipulation system. The semi-automated manipulation of a single zebrafish embryo, as well as a series of comparison experiments, is carried out. Experimental results demonstrate that the microgripper has reliable capability of picking, moving, holding and releasing the zebrafish embryo. Specifically, it performs fairly well in immobilizing and limiting the excessive deformation of the embryo. Finally, based on teaching, the whole process of zebrafish embryo microinjection is programed and performed automatically, thus demonstrating great strengths and performance of the microgripper in zebrafish embryo micro-manipulation.

Iterative Learning Control for V-Shaped Electrothermal Microactuator

The paper introduces a modified version of a Proportional Integral Derivative (PID)-type iterative learning algorithm, which is very simple to implement on a digital control device for tracking control of a continuous-time system. The simulative application of it is for controlling a V-shaped electrothermal microactuator (VEM) and is carried out by using a Simscape model of VEM for the purpose that the asymptotic tracking behavior of system output to desired trajectory will be verified in a virtually real environment. Obtained simulation results confirm that the introduced iterative learning algorithm has not only provided a good output tracking behavior, as expected, but also is robust in the sense of reducing external disturbance effects.

The design of high strength electro-thermal micro-actuator based on the genetic algorithm

Micro-actuator has applied on the microrobotics, microfluidics et al. widely. In general, to obtain the maximum output force is the designed requirement of electro-thermal actuator. However, the displacement for the force output will result in the stress concentration. The important issue is to reduce the failure of the electro-thermal actuator resulted from the stress concentration. This paper proposes an optimal process that involves using the finite element method and genetic algorithm to maximize the displacement and output force and minimize the stress concentration for enhancing the performance of an electro-thermal micro-actuator. The results were validated by comparing the simulated results of a previous study. Geometric design parameters were used for determining the displacement, output force, and stress concentration. The optimal design was proved to increase the life expectancy of micro-actuator.

Modeling of multiphysics coupling and performance analysis of V-shaped electrothermal microactuator

Electrothermal microactuators have a very promising future in MEMS applications since they can generate large displacement and force with low actuating voltages and small device areas. In this paper, a temperature distribution and unload displacement model of a V-shaped electrothermal microactuator are presented. In order to prove the accuracy of the model, finite element analysis (FEA) and experimental results are provided for comparison. The results of temperature profile and unload displacement output, which are from the model calculation, FEA and experimental test, agree well with each other. It gives an indirect proof that the model is correct and FEA calculation is practicable. It can be shown that the shape of the actuator has no effect on the maximum temperature, and the unload displacement and output force depend on the beam length and inclined angle of the actuator.

Modelling of Chevron electrothermal actuator and its performance analysis

In this work, a Chevron electrothermal actuator is designed and its analytical model is developed. Chevron actuator works on the principle of Joules heating effect and thermal expansion. Aluminum is chosen as a material for actuator because of its good electrical and thermal properties and also it produces large displacement of about 10.94 µm with lower operating temperature of 448 °C for single beam. The Chevron based electrothermal actuator holds good when compared to the other conversion based conventional microactuators in terms of applied voltage vs displacement achieved. The analytical model is validated by comparing with 3D finite element model. The mathematical modeling is derived and the analytical calculations were performed over the mathematical model. The displacement and temperature results obtained from simulation and analytical models are in good agreement. The comparative results provides the proof for having a better performance in simulation which is again validated by the 0.3% of error with the analytical modeling of the Chevron based electrothermal microactuator.

Efficiency enhanced novel 3T heads V-beam microactuator for low power applications

Structural Optimization and efficiency improvement of an electrothermal microactuator compared to its fundamental architectural design is reported in this paper. The principal component in the proposed device design is an electrothermal V-beam microactuator which is implemented to actuate a pre-stressed bistable curved beam, a switching element and thereby establishes a bistable MEMS switch. The proposed device is fabricated on SOI wafer with 10 µm thick device Si layer using SOIMUMPs(Silicon-On-Insulator Multi User MEMS Process) process with 3 masks. The optimized design provides 11.11% improvement in the actuation force and 8.81% increase in the axial displacement compared to the conventional V-beam actuator.