İlgi alanları

• MakaleYalnız künye2026Scopus SJRQ2/r/bayburt/12800
  Sorting chiral active Brownian particles with radially modulated optical fields

  Yücel, Harun

  This study presents a numerical investigation of sorting chiral active Brownian particles using radially modulated optical fields. How these factors affect particle trajectories and spatial distributions is examined by systematically varying particle parameters such as self-propulsion speed, angular velocity, and optical fringe modulation. It is found that the average orbit radius of the particle trajectory strongly depends on the ratio of the self-propulsion speed to the average velocity induced by the moving fringe pattern. In particular, the average orbit radius converges to the theoretical orbit radius defined by the ratio of the self-propulsion speed to the angular velocity in the regime where the self-propulsion speed is greater than the fringe-induced velocity. In mixtures of particles with differing chirality, the dynamic response to circular fringe patterns enables effective classification based on motility. These findings suggest that structured light fields can be used to manipulate and selectively sort chiral active particles, which have potential applications in optical micromanipulation and active matter research.

  İncele
• MakaleAçık Erişim2025/r/bayburt/15950
  Simulation Study on The Sorting of Chiral Active Brownian Colloids By Optical Barriers

  Yücel, Harun

  This study considers the dynamics of chiral active Brownian particles (CABPs) through numerical simulations conducted under the influence of an optical field. Unlike passive Brownian particles, CABPs possess a propulsion mechanism and a chiral torque that induce curved trajectories, complex motion, and out-of-equilibrium behavior. These properties make CABPs interesting for both theoretical research and potential applications in the control of active matter. In simulations, CABPs are modeled as spherical particles with a refractive index suspended in a fluid medium (water). When illuminated by an optical field, these particles experience optical forces due to the momentum transfer from the light field, which affects their motion. This interaction provides a powerful method for guiding, confining, or sorting them based on their motile characteristics. As a result, the study demonstrates that optical fields can serve as both static and dynamic barriers, significantly influencing the trajectories of particles. The findings present that optical landscapes can separate and orient CABPs based on their propulsion speed and chirality. The study emphasizes the potential of optical manipulation as a tunable technique for chiral active particles in complex environments.

  İncele
• MakaleAçık Erişim2025Scopus SJRQ2/r/bayburt/11525
  Determining errors in force measurements for colloids close to contact

  Yücel, Harun

  Due to diffraction patterns in light microscopy, the overlapping of colloid images introduces minor errors in determining particle positions, which affecting the accuracy of observing interactions between colloids near contact. This study quantitatively investigates the errors arising from the overlapping effect in force measurements between two closely positioned colloids using digital video microscopy (DVM). For this aim, computer simulations were conducted to obtain the positions of two optically trapped colloids interacting based on a force model and particle images were generated as a time series using experimental particle intensity profiles for two different particle sizes. These generated images were analyzed using tracking algorithms from the literature and the interaction forces were extracted and compared with theoretical force values. The results demonstrated that diffraction patterns significantly influence the accuracy of particle position detection and interaction force calculations. Large diffraction patterns and intensity fluctuations in an image introduce significant errors. However, these errors can become significantly smaller in the presence of large forces and may therefore be considered negligible.

  İncele
• MakaleAçık Erişim2023Scopus SJRQ2/r/bayburt/13018
  A simulation study on colloid diffusion under time-varying optical potentials

  Yücel, Harun

  With its momentum transfer, light is a primary tool for manipulating microscale objects in various research fields, including physics, chemistry, and biology. Optical force fields, also known as energy landscapes, play a crucial role in manipulating micro- and nano-sized objects, enabling the sorting of mixed micro-sized particles. This study investigates the effect of time-varying periodic optical fields created by a structured light illumination technique on the diffusion motion of micro-sized colloidal particles suspended in a liquid. A simulation code is developed to calculate the optical force acting on particles due to any time-varying optical force field. Simulations are performed to produce trajectories of particles of different sizes suspended in a liquid for different illumination patterns. The results show that the average velocities of the particles depend on the projected optical pattern parameters and that mixtures of particles of different sizes can be separated using time-varying sequential patterns, thereby improving particle separation resolution.

  AtıfScopus2·WoS2·OpenAlex3

  İncele
• MakaleAçık Erişim2021Scopus SJRQ1/r/bayburt/12098
  Toolbox for tracking and analyzing crowded mixture of colloidal particles

  Yücel, Harun; Velu, Sabareesh K.P.

  We present a MATLAB-based multiple particle tracking (mPosTracker) algorithm to detect and track crowded colloidal particles that are two-dimensionally imaged using digital video microscopy. Our algorithm adopts three optional detection methods using threshold settings namely; centroid method (CM), radial symmetry method (RSM) and partial radial symmetry method (pRSM). In contrast to other reported algorithms, it allows classifying a maximum of three types of particles based on area or intensity. Furthermore, we include a toolbox to perform quantitative particle analysis like number density, trajectories with mean square displacement, and Voronoi cells with six-fold bond parameters to reveal the physics of examined dataset. To demonstrate the abilities of mPosTracker, we show the analysis outcomes on synthetically and experimentally acquired time-lapse microscopy datasets. mPosTracker is suitable for studying the dynamics of crowd behaviour, self-assembly, and manipulation of multi-component colloids under external fields.

  AtıfScopus2·WoS2·OpenAlex2

  İncele
• BildiriAçık Erişim2019/r/bayburt/13186
  Tracking particle near a flat surface in digital video microscopy

  Yücel, Harun

  Digital video microscopy (DVM) is an important tool to obtain quantitative information about underlying physics in colloidal systems. DVM, however, has the overlap problem caused by particle's diffraction pattern when the detected particles are close to contact. This overlapping problem limits the tracking methods in determining accurate particle position that reflects all interactions exerting to particles or objects in colloidal studies. The problem occurs not only between two spherical particles close to each other but also when a spherical particle is close to a rod shaped particle which have a flat surface. In this study, the simulation results on the tracking spherical particle placed near the flat surface of a rod particle in 2D digital video microscopy are reported. This work shows that the overlap problem can be resolved by using a fraction of the intensity distribution of a spherical particle which is close to a flat surface.

  İncele
• BildiriYalnız künye2018/r/bayburt/12439
  Threshold effect on particle tracking algorithms

  Yücel, Harun; Velu, Sabareesh K. P.

  Automated particle tracking algorithms are widely used by soft matter physicists as a research tool to detect and construct the trajectories of micron-sized particles in ffuids. Analyzing these trajectories will uncover the physics of the investigated particles mainly on the type of motion they undergo making them suitable for potential applications. A plethora of methods has been proposed and used for detection and tracking. In this work, we examine the performance of two commonly used tracking algorithms in terms of threshold dependencies in digital video images. One of them is the centroid method (CM), a well-known and used algorithm and the other is radial symmetry method (RSM) which is recently proposed. Here, we generate the synthetic digital video images consisting of randomly placed multiple particles and compare the absolute errors on the particle detection by varying threshold values. Our results suggest that both algorithms show dependence on the threshold value and on comparison RSM algorithm performs better than the CM algorithm when the noise level is zero. Moreover, the measured absolute errors show a strong dependence on threshold values when noise levels are increased (up to 20) especially for the RSM algorithm.

  AtıfScopus1·WoS1·OpenAlex1

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