A Study on Finding Optimum Parameters of a Diamagnetically Driven Untethered Microrobot

Demirçalı, Ali Anıl; Erkan, Kadir; Üvet, Hüseyin

doi:10.4283/jmag.2017.22.4.539

Cited by 7 publications

(12 citation statements)

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“…Also, according to the position of the lifter magnet, microrobot 3D orientation can be provided. In our previous studies, the maximum and minimum microrobot operating points are also indicated by controlling the levitation height on the microrobot z -axis [ 24 , 25 ]. In those studies, we also show how to find optimum parameters in order to setup a diamagnetically levitated microrobot manipulation system.…”

Section: Introductionmentioning

confidence: 99%

Micro-UFO (Untethered Floating Object): A Highly Accurate Microrobot Manipulation Technique

et al. 2018

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A new microrobot manipulation technique with high precision (nano level) positional accuracy to move in a liquid environment with diamagnetic levitation is presented. Untethered manipulation of microrobots by means of externally applied magnetic forces has been emerging as a promising field of research, particularly due to its potential for medical and biological applications. The purpose of the presented method is to eliminate friction force between the surface of the substrate and microrobot. In an effort to achieve high accuracy motion, required magnetic force for the levitation of the microrobot was determined by finite element method (FEM) simulations in COMSOL (version 5.3, COMSOL Inc., Stockholm, Sweden) and verified by experimental results. According to position of the lifter magnet, the levitation height of the microrobot in the liquid was found analytically, and compared with the experimental results head-to-head. The stable working range of the microrobot is between 30 µm to 330 µm, and it was confirmed in both simulations and experimental results. It can follow the given trajectory with high accuracy (<1 µm error avg.) at varied speeds and levitation heights. Due to the nano-level positioning accuracy, desired locomotion can be achieved in pre-specified trajectories (sinusoidal or circular). During its locomotion, phase difference between lifter magnet and carrier magnet has been observed, and relation with drag force effect has been discussed. Without using strong electromagnets or bulky permanent magnets, our manipulation approach can move the microrobot in three dimensions in a liquid environment.

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Section: Introductionmentioning

confidence: 99%

Micro-UFO (Untethered Floating Object): A Highly Accurate Microrobot Manipulation Technique

et al. 2018

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“…Since the pyrolytic graphite is a diamagnetic material with a magnetic permeability of

, it encloses the microrobot within the boundaries of magnetic field lines of the lifter-magnet. Because of this, we can achieve more stable levitation characteristics inside the liquid [ 32 , 33 ].…”

Section: Mathematical Modelmentioning

confidence: 99%

“…As shown in Figure 1 , the microrobot moving in the x direction is not parallel to the surface during its motion due to the undesired torque

acting on it. For a microrobot, for which the moment of inertia is taken as

(μg mm 2 ), a relation between the angular acceleration and undesired torque can be determined [ 32 , 33 , 34 ]. Accordingly, Equation (1) will be used to calculate the angle value at which the lifter-magnet should be held in order to avoid the generation of undesired torque values ( Figure 2 ).…”

Section: Mathematical Modelmentioning

confidence: 99%

“…The acceleration-dependent mathematical model is expressed in Equations (3)–(5), in which the robot mass is m r [ 32 , 33 , 34 ]. The forces exerted on the microrobot are shown in Figure 4 B.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…The forces exerted on the microrobot are shown in Figure 4 B. For a robot with a mass of 2.92 μg, robot acceleration can be determined for known values of lifting force (12.788 μN), speed-dependent friction force [ 33 ], and gravitational force (28.741 μN). The relationship between phase difference and the microrobot acceleration has been investigated in a different study [ 32 ].…”

Section: Mathematical Modelmentioning

confidence: 99%

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Stabilization of Microrobot Motion Characteristics in Liquid Media

Demirçalı

Üvet

2018

Micromachines

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Magnetically actuated microrobot in a liquid media is faced with the problem of head-tilting reaction caused by its hydrodynamic structure and its speed while moving horizontally. When the instance microrobot starts a lateral motion, the drag force acting on it increases. Thus, the microrobot is unable to move parallel to the surface due to the existence of drag force that cannot be neglected, particularly at high speeds such as >5 mm/s. The effect of it scales exponentially at different speeds and the head-tilting angle of the microrobot changes relative to the reference surface. To the best of our knowledge, there is no prior study on this problem, and no solution has been proposed so far. In this study, we developed and experimented with 3 control models to stabilize microrobot motion characteristics in liquid media to achieve accurate lateral locomotion. The microrobot moves in an untethered manner, and its localization is carried out by a neodymium magnet (grade N48) placed inside its polymer body. This permanent magnet is called a carrier-magnet. The fabricated microrobot is levitated diamagnetically using a pyrolytic graphite placed under it and an external permanent magnet, called a lifter-magnet (grade N48), aligned above it. The lifter-magnet is attached to a servo motor mechanism which can control carrier-magnet orientation along with roll and pitch axes. Controlling the angle of this servo motor, together with the lifter-magnet, allowed us to cope with the head-tilting reaction instantly. Based on the finite element method (FEM), analyses that were designed according to this experimental setup, the equations giving the relation of microrobot speed with servo motor angle along with the microrobot head-tilting angle with servo motor angle, were derived. The control inputs were obtained by COMSOL® (version 5.3, COMSOL Inc., Stockholm, Sweden). Using these derived equations, the rule-based model, laser model, and hybrid model techniques were proposed in this study to decrease the head-tilting angle. Motion control algorithms were applied in di-ionized water medium. According to the results for these 3 control strategies, at higher speeds (>5 mm/s) and 5 mm horizontal motion trajectory, the average head-tilting angle was reduced to 2.7° with the ruled-based model, 1.1° with the laser model, and 0.7° with the hybrid model.

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Highly Mobile Levitating Soft Actuator Driven by Multistimuli‐Responses

Kim

Pyo

Kim

2020

Adv Materials Inter

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Soft actuators exhibit activeness and flexibility and are widely used as next‐generation intelligent devices. However, their locomotion depends on friction with contact surfaces that restrict their movement. To overcome this limitation, a noncontact‐type multiresponsive soft actuator that levitates in a magnetic field is proposed. This soft actuator can respond to humidity, heat, and diamagnetic repulsion force stimuli, resulting in high degrees of freedom and multiple motions. The soft actuator is fabricated by coating a highly hygroscopic membrane onto a diamagnetic graphite film, which enables the actuator to levitate in the magnetic field. Bending actuation is induced by the swelling mismatch between the two layers via the hygrothermal response. The translational force driven by local concentrated heating of the actuator leads to the realization of high‐speed linear and curvilinear motions. Frictionless rotational motion is also realized remotely with broad heating of an asymmetrically bent soft actuator, generating nonzero torque acting on the floating soft actuator. The proposed levitating soft actuators are applied to a fast and reliable capsule‐delivery gripper and a remotely controllable levitated motor. The soft actuator exhibits the potential to be applied in a wide range of applications, such as soft robotics and smart mechanical devices.

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A Study on Finding Optimum Parameters of a Diamagnetically Driven Untethered Microrobot

Cited by 7 publications

References 0 publications

Micro-UFO (Untethered Floating Object): A Highly Accurate Microrobot Manipulation Technique

Micro-UFO (Untethered Floating Object): A Highly Accurate Microrobot Manipulation Technique

Stabilization of Microrobot Motion Characteristics in Liquid Media

Highly Mobile Levitating Soft Actuator Driven by Multistimuli‐Responses

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