Publishing type：Research paper (scientific journal)   Publisher：Cambridge University Press ({CUP})  

Electromagnetic actuation systems (EMA) have excelled themselves in microscale manipulation. Yet, the fastened structure of the current systems tethers the controlled workspace. In this paper, a new electromagnetic actuation principle is investigated. The actuator structure consists of a pair of coaxially movable electromagnets integrated to a robotic manipulator. The pair induces a coaxial homogeneous magnetic field or gradient to control the magnitude of the magnetic torque or force by changing the distance between the electromagnets asymmetrically. The robotic manipulator, on the other hand, transports the pair at five degrees of freedom to manipulate a microrobot in 3D space by closed-loop control with integrated vision feedback system. Numerical analyses are performed to investigate the induced electromagnetic field at the symmetrical/asymmetrical configuration of the coaxial pair. Accordingly, a correlation between the magnitude of the magnetic force and the asymmetric distance is obtained for flexible force control. A proof of concept prototype is constructed to validate the proposed actuation principle and evaluate its performance experimentally. The experimental results verify the numerical analysis and show the system applicability of inducing controlled forces on a micro-object in 2D and 3D workspaces at a velocity range of 65 to 157 μm/s. Moreover, micromanipulation on a helical route is also demonstrated with an absolute error mean from the reference path of 191 μm.

DOI： 10.1017/S0263574722000418

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1080/27660400.2021.1963642

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The recent development of wearable interfaces raises the challenge of their thermal management requirements. Motivated by that, a novel flexible loop heat pipe (FLHP) of high heat transfer efficiency to be mounted on wearable devices is presented. Initially, the design of the FLHP is caried out by a constructed thermal analysis model. The FLHP is then formed from PDMS by a developed microfabrication process. A proof of concept FLHP prototype with dimension of 80×45×1.2 mm with high flexibility is obtained. The thermal performance test was conducted at three different heat loads. The results show the FLHP operates successfully with promising potential to be applied on wearable electronics or any other flexible MEMS applications.

DOI： 10.1109/MEMS51782.2021.9375378

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Electromagnetic actuation systems have remarkably proved themselves in the field of contactless power transmission systems. Nevertheless, the stationary position of the operated electromagnets or their rotation around a fixed axis resulted in a restrictive and limited versatile workspace. In this paper, a new design of a steel cored solenoidal coil is proposed for a novel microrobot electromagnetic actuator. The new system combines a 6 DOF industrial robotic manipulator with co-axially movable electromagnets. Considering the maximum weight and workspace limitations of the robotic manipulator, seven essential dimensions of the electromagnet were investigated with the aid of a simulation software. A set of parametric studies were carried out in order to optimize the homogeneity of the induced magnetic field at the highest achievable intensity based on Ad hoc method. The results showed that an electromagnet with a square prism core and a large front, induces a more homogeneous and intense magnetic field. Moreover, by shortening the length of the coil and increasing the length of the core, the intensity of the magnetic field significantly increases without much affecting its homogeneity. The electromagnet was fabricated according to the final result of the numerical studies and evaluated by performing experimental measurements on the induced magnetic field. Furthermore, with several programed motions, the performance of the proposed untethered electromagnetic actuation system was demonstrated experimentally.

DOI： 10.1016/j.sna.2018.11.027

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Publisher：Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)  

This paper describes a macro/micro robot manipulation system consisting of an electromagnet couple and an industrial manipulator. The system has capability of motion 6 Degrees of Freedom (6 DOF) providing the same amount of DOFs to the manipulation of the microrobot. A custom-design mechanism which is attached onto the tip of the industrial manipulator provides the required magnetic field profiles for force and torque generation using coil couple and their ability sliding motion in linear directions. This combination provides reprogrammable working space for the microrobot manipulation. Robot Operating System (ROS) based programming integrates all the subsystem software. Visual feedback assures the real-time microrobot position and orientation data. Close-loop motion control of the microrobot was tested using custom designed constrained paths take part in a plane. Experiment were presented for specific motions of the microrobot to show the microrobot motion abilities. The results are promising which may orient to the applications like micro assembly and micromanipulation.

DOI： 10.1007/978-3-030-26118-4_1

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

The main purpose of this study is to focus the light for the first time on the recognized re-dispersion ability of the sonicated MWCNTs within low viscous mineral oil. For that, pure MWCNTs, without any special treatment, were dispersed in mineral oil by sonication without using any stabilization method. After full agglomeration, it was realized that agitating, shaking or even blowing compressed air on the agglomerated nanolubricant is able to break down the aggregation of the MWCNTs. Microscopic video is presented to clarify the behavior of the tubes during the re-dispersion process. Quantitatively, particle size distribution (PSD) was employed to evaluate the re-dispersion quality. The viscosity and thermal conductivity of both recently sonicated and re-dispersed samples were also investigated with accurate measurement setups at four different weight concentrations (0.05, 0.1, 0.2 and 0.3 wt.%). It was observed that the sonicated MWCNTs are separated, saturated, lubricated, and surrounded by oil layers, which not only ease its motion within the lubrication oil, but also give them the ability of detaching by applying any slight force. Moreover, the PSD results with the equal values of the viscosity and thermal conductivity, obtained within the uncertainty of the measurements, confirm that the MWCNTs were re-dispersed to the same quality of the recently sonicated ones by just shaking.

DOI： 10.1016/j.colsurfa.2017.10.085

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Publishing type：Research paper (scientific journal)   Publisher：Key Engineering Materials  

In the presented work, thermal conductivity of CuO and its viscosity at three different weight concentrations were investigated. A two-steps method was deployed in order to sonicate successfully CuO nanolubricants samples at three different weight concentrations (0.2, 0.5, & 1 wt%). The measurements of thermal conductivity were carried out with a lab-made measurement set, which is based on a 3method. The obtained enhancements were 1%, 1.7% and 2.8% for 0.2, 0.5, and 1 wt.%, respectively. Viscosity was also investigated under different temperatures and it was obtained that adding CuO to the mineral oil had a slight effect on its viscosity at lower concentrations. However, the maximum increment at lower temperature for the higher concentration was 13.1%. Based on the enhancement in thermal conductivity and the low increment in viscosity, CuO nanolubricant can be recommended for enhancing the heat transfer characteristic of the refrigeration compressor.

DOI： 10.4028/www.scientific.net/KEM.750.159

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Language：English   Publishing type：Research paper, summary (international conference)  

The recent development of wearable interfaces raises the challenge of their thermal management requirements. Motivated by that, a novel flexible loop heat pipe (FLHP) of high heat transfer efficiency to be mounted on wearable devices is presented. Initially, the design of the FLHP is caried out by a constructed thermal analysis model. The FLHP is then formed from PDMS by a developed microfabrication process. A proof of concept FLHP prototype with dimension of 80×45×1.2 mm with high flexibility is obtained. The thermal performance test was conducted at three different heat loads. The results show the FLHP operates successfully with promising potential to be applied on wearable electronics or any other flexible MEMS applications.

DOI： 10.1109/MEMS51782.2021.9375378

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)  

This paper describes a macro/micro robot manipulation system consisting of an electromagnet couple and an industrial manipulator. The system has capability of motion 6 Degrees of Freedom (6 DOF) providing the same amount of DOFs to the manipulation of the microrobot. A custom-design mechanism which is attached onto the tip of the industrial manipulator provides the required magnetic field profiles for force and torque generation using coil couple and their ability sliding motion in linear directions. This combination provides reprogrammable working space for the microrobot manipulation. Robot Operating System (ROS) based programming integrates all the subsystem software. Visual feedback assures the real-time microrobot position and orientation data. Close-loop motion control of the microrobot was tested using custom designed constrained paths take part in a plane. Experiment were presented for specific motions of the microrobot to show the microrobot motion abilities. The results are promising which may orient to the applications like micro assembly and micromanipulation.

DOI： 10.1007/978-3-030-26118-4_1

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Language：English   Publishing type：Research paper, summary (international conference)  

A guided microrobot position control methodology is introduced in this paper. Using an electromagnetic actuator (EMA) as an end-effector of a robot manipulator, it is possible to have microrobot follow a correlated path with robot manipulator motion in case when there is no task space feedback from microrobot environment. For this purpose, a concept EMA system with an actuation principle depending on the magnetic field homogeneity and gradient generated by two coaxially aligned electromagnets is introduced. The functionality of developed system is experimentally analyzed for translational and rotational motion tracking cases. It is observed that the correlation between the robot manipulator motion and microrobot motion is nearly 1 in x and y direction.

DOI： 10.1109/CEIT.2018.8751803

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：Mechanisms and Machine Science  

This paper proposes a comparative study in order to investigate the effect of the coil geometry on the intensity and homogeneity of the magnetic field. For this purpose, a solenoid with rectangular prism core and two different coil shapes, cylindrical and cuboid, was modeled. Several finite element numerical studies at different structural design parameters combinations for two different distances between the coils were carried out. The obtained results were evaluated according to the flux intensity and the homogeneity at the center region between the coils. Consequently, it was found that cylindrical coils generate higher flux intensity with more homogeneous magnetic field.

DOI： 10.1007/978-3-319-60702-3_25

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