Tabak, Ahmet Fatih

Tabak, Ahmet Fatih

Name Variants

Tabak, Ahmet Fatih
A.,Tabak
A. F. Tabak
Ahmet Fatih, Tabak
Tabak, Ahmet Fatih
A.,Tabak
A. F. Tabak
Ahmet Fatih, Tabak
Tabak, A.F.

Job Title

Dr. Öğr. Üyesi

Email Address

Ahmetfatıh.tabak@khas.edu.tr

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Scholarly Output

11

Articles

3

Citation Count

0

Supervised Theses

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Now showing 1 - 10 of 11

Citation Count: 0
Mathematical modeling to the motion control of magnetic nano/microrobotic tools performing in bodily fluids, especially blood/plasma
(Elsevier, 2021) Tabak, A.F.
The use of microrobotic systems for therapeutic applications has been a hot topic for the last two decades with ever growing interest. One particular application envisioned is the use of untethered robotic devices of the size of a cell performing in the circulatory system. These robotic devices do not possess the volume to house sensors. Furthermore, they are supposed to perform in hard to reach locations, that is, under composite layers of biological tissue of different physical properties impeding the effectiveness of tracking and actuation. On top, the local flow fields of biological fluids such as the bloodstream imposes non-Newtonian, spatially asymmetrical, and partially chaotic conditions on the drag felt by the microrobots. It is common practice to simulate the overall system dynamics before building a robot. This procedure is a requirement for characterization and optimization, as well as model-based control, in some cases, to obtain the best performance for a specific set of mission parameters. Moreover, in the following subject matter it is crucial to model the robotic system in great detail as the mission parameters are constantly subject to spatial and temporal changes. Predicting states of the robot, estimating the local flow conditions, and achieving an addressable and controllable gait rely on understanding the coupled dynamics of the robot, the environment, and the actuation method. This chapter is an attempt to understand the interdisciplinary nature of such microrobotic systems, along with motion control, based on the simplified mathematical models under realistic assumptions. © 2022 Elsevier Inc. All rights reserved.
Citation Count: 0
Independent Joint Control Simulations on Adaptive Maneuvering of a Magnetotactic Bacterium via a Single Permanent Magnet
(2020) Tabak, Ahmet Fatih
The use of micro-robotic systems in non-invasive medicine has been heavily promoted in the literature for the last decade. The studies usually focus on artificial or biohybrid microswimmers of various origins subject to the effect of an external electromagnetic field controlled by a computer. Although there exist several motion control studies shared to date, control of a bio-hybrid microswimmer has rarely been demonstrated employing an open kinematic chain, in detail. In this work, motion control of an isolated magnetotactic bacterium cell (Magnetospirillum Gryphiswaldens) is presented via a magnetic field actively positioned by an open kinematic chain. The cell is modeled with its complete environment to make it as realistic as possible along with the magnetic torque, which is induced by a single magnet attached at the end effector of a robotic arm, exerted on it for maneuvering control. The control is based on a proportional – integral – derivative (PID) gain scheme with adaptive integral gain to focus on a particular steady-state error with discontinuous reference signals. The control signal is transformed into pulse width modulation (PWM) signals to drive the motors articulating the joints of the open kinematic chain, the inverse kinematics of which is designed to be simple enough to achieve independent joint control. A numerical analysis of the coupled system is carried out in the time domain. The performance of the said motion control approach is investigated for each degree of freedom for the planar motion of the microswimmer. Simulations demonstrate a planar open kinematic chain is capable of control the gait of the microswimmer while following its trajectory near a planar boundary via independent joint control. Furthermore, simulations demonstrate that the effective magnetic inertia and the shear stress results in a small but certain lag in the motion control performance of the overall system.
Citation Count: 0
Orbital Characterization Study for the Hydrodynamic Micro Tweezers: Simulated Performance with an Active Particle
(Institute of Electrical and Electronics Engineers Inc., 2021) Duzenli, S.; Surer, J.; Tabak, A.F.
In micro-robotics, micromanipulation can be utilized via diverse strategies for the trapping, selection, and manipulation of microparticles especially in biomedical applications. One of the most encountered problems in the research studies is the deformation or damage that might be caused by the micro object. The non-contact micromanipulation methods that are proposed in the literature aim to suggest efficient solutions to limit the deforming effects. These methods can be categorized based on the technique used in the system. The utilization of hydrodynamic forces is one of the most promising techniques in the literature. However, the numerical analysis and the dynamic performance predictions of these systems are often omitted. This study tries a new approach with a robotic-modeling-based comprehensive mathematical model to hydrodynamic interaction and the performance simulation of the orbital characterization of a hydrodynamic micro-tweezers system. Furthermore, we demonstrate the performance of a micro tweezers system on a particular active particle, i.e., E. Coli minicell. The system consists of a magnetic spherical particle submerged in an aqueous environment, rotating by the effects of the external magnetic field resulting in a free vortex. In return, the vortex is employed to trap the said active particle. © 2021 IEEE.
Citation Count: 2
Numerical Investigations on the Hydrodynamic Interaction between an E. Coli Minicell and a Micro Tweezers
(Institute of Electrical and Electronics Engineers Inc., 2021) Tabak, A.F.
The study of robotic micromanipulation is important for biomedical applications with live cells. Hydrodynamic trapping is arguably more favorable owing to the apparent lack of temperature gradients and tactile interaction. However, it offers challenges of modeling due to the complex nature of the physics governing the mechanics of trapping. This study aims to present a fully deterministic Multiphysics modeling of the hydrodynamic micro tweezers that actuated by external magnetic fields in a virtually infinite Newtonian fluid. Equation of motion is written to include all hydrodynamic interaction between the particles along with contact force. Early results dictate that it is possible to observe stable orbit for different cases although the interactions could rely on different physical phenomena in part. © 2021 IEEE.
Citation Count: 0
Simulation Studies for Motion Control of Multiple Biohybrid Microrobots in Human Synovial Fluid With Discontinuous Reference Signals
(2021) Tabak, Ahmet Fatih
It is envisioned that biomedical swarms are going to be used for therapeutic operations in the future. The utilization of a single robot in live tissue is not practical because of the limited volume. In contrast, a large group of microrobots can deliver a useful amount of potent chemicals to the targeted tissue. In this simulation study, a trio of magnetotactic bacteria as a task-force, Magnetospirillum Gryphiswaldense MSR-1, is maneuvered via adaptive micro-motion control through an external magnetic field. The magnetic field is induced by a single permanent magnet positioned by an open kinematic chain. The coupled dynamics of this small group in the human synovial tissue is simulated with actual magnetic and fluidic properties of the synovial liquid. The common center of mass is tracked by the equation of motion. The overall hydrodynamic interaction amongst all three bacteria is modeled within a synovial medium confined with flat surfaces. A bilateral control scheme is implemented on top of this coupled model.The position of the common center of mass is used as the reference point to the end-effector of the robotic arm. The orientation of the magnetic field is rotated to change the heading of the bacterial-group in an addressable manner. It has been numerically observed that controlling the common swimming direction of multiple bacteria is fairly possible. Results are presented via the rigid-body motion of the robotic task-force as well as the fluidic and magnetic force-components acting on the bacteria along with the bilateral control effort in all axes.
Citation Count: 28
Transducer Technologies for Biosensors and Their Wearable Applications
(Mdpi, 2022) Polat, Emre Ozan; Cetin, M. Mustafa; Tabak, Ahmet Fatih; Bilget Guven, Ebru; Uysal, Bengu Ozugur; Arsan, Taner; Kabbani, Anas
The development of new biosensor technologies and their active use as wearable devices have offered mobility and flexibility to conventional western medicine and personal fitness tracking. In the development of biosensors, transducers stand out as the main elements converting the signals sourced from a biological event into a detectable output. Combined with the suitable bio-receptors and the miniaturization of readout electronics, the functionality and design of the transducers play a key role in the construction of wearable devices for personal health control. Ever-growing research and industrial interest in new transducer technologies for point-of-care (POC) and wearable bio-detection have gained tremendous acceleration by the pandemic-induced digital health transformation. In this article, we provide a comprehensive review of transducers for biosensors and their wearable applications that empower users for the active tracking of biomarkers and personal health parameters.
Citation Count: 0
Motion Control for Biohybrid Multiscale Robots
(IEEE, 2020) Tabak, Ahmet Fatih
Complex gaits of microswimmer robotic devices could be controlled via discretized reference signals and adaptive control scheme. A biomedical micro-robotic system offers a nontrivial control problem without tactile contact or tether. Moreover, such devices can incorporate live cells to achieve biocompatibility for therapeutic applications introducing additional complexity to the system dynamics and control effort. Additionally, a coupled hybrid system of a macroscale open kinematic chain and a self-propelling bacterium cell constitutes a multiscale hybrid system that can be used for medical applications of different sorts. In this study, the performance of a system of aforementioned qualities is investigated with an adaptive control strategy under in vitro conditions. Results demonstrate that the control method of choice offers a promising approach to the described scenario.
Citation Count: 0
Simulated Motion Control of a School of Microrobots With Random Walks
(Institute of Electrical and Electronics Engineers Inc., 2022) Tabak, A.F.
The dynamics of individual elements in a swarm moving in biological fluids is an important aspect to ascertain the effectiveness of cumulative motion control. The hydrodynamic interaction between the swarm and surrounding walls as well as between the micro-swimmers, i.e., magnetotactic bacteria, within the swarm are affected by Brownian motion. A small group of magnetically-controlled bacteria swimming in a biological fluid could be simulated in a simplified fashion to design and test controllers for addressable motion with random walks. Furthermore, the disruptive effect of the random walks might prove detrimental to the control performance. This paper showcases a simulation study of adaptive motion control for a trio of magnetotactic bacteria swimming as a group in human synovial fluid. The bacterial group is confined by the joint geometry and maneuvered by the external magnetic field of a permanent magnet positioned by an open kinematic chain. Results show that it is possible to control the yaw angle of the bacterial group while swimming under the influence of repulsive force and the Brownian noise although each swimmer follows a different path. It is further observed that, when bacteria came in contact with solid surfaces, the control algorithm could be prone to misinterpreted sensory data. © 2022 IEEE.
Citation Count: 0
Mesenchymal Stem Cell Diffusion Integrated Mechano- Biology Analysis of 3d Scaffolds
(Mary Ann Liebert, Inc, 2023) Sahin, Mervenaz; Tabak, Ahmet Fatih; Sendur, Gullu Kiziltas; Ghassabi, Ata Alipour
[Abstract Not Available]
Citation Count: 0
Non-Contact Micromanipulation Of A Single E. Coli Minicell
(2021) Tabak, Ahmet Fatih; Sürer, Jiyan
Today, a variety of methods are available for micro-scale transportation without inflicting damage on biological samples. There are several numerical and experimental studies in the literature that make use of microrobots to manipulate particles in non-contact performances. One of the applications used to mitigate the aforementioned risk is non-contact micro manipulation by hydrodynamic effects, and with the micro-objects floating around the core of a free vortex this method can be implemented effectively. However, a robotic model predicting the dynamics of such microsystems is rare in the literature and yet to be applied for manipulation of a bacterium. In this paper, a single magnetic particle that is assumed to be held in a fixed place while rotated by an external magnetic field, and an E. Coli minicell swimming in the free vortex induced by the described rotation. The mathematical model and the numerical simulations presented here via linear set of equations for rigid body-motion under the magnetic and hydrodynamic forces are built in cylindrical coordinates. Results demonstrate the numerical stability of the robotic model along with predicted-motion pointing to a steady periodic orbit around the vortex center for a total of 600 periods of simulated magnetic field rotation. Results to the numerical experiments are focused on the rigid-body rotation of E. Coli minicell, the propulsive force of the rotating helical tail of the bacterium, and acceleration, speed, and displacement of the bacterium with respect to the center of the vortex.