scholarly journals Escape trajectories of single-beam optically trapped micro-particles in a transverse fluid flow

2006 ◽  
Vol 14 (4) ◽  
pp. 1685 ◽  
Author(s):  
Fabrice Merenda ◽  
Gerben Boer ◽  
Johann Rohner ◽  
Guy Delacrétaz ◽  
René-Paul Salathé
Keyword(s):  
Fluid Flow ◽  
Single Beam ◽  
Micro Particles ◽  
Escape Trajectories ◽  
Optically Trapped

scholarly journals Coated High-Refractive-Index Barium Titanate Glass Microspheres for Optically Trapped Microsphere Super-Resolution Microscopy: A Simulation Study

Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 84
Author(s):  
Xi Liu ◽  
Song Hu ◽  
Yan Tang
Keyword(s):  
Refractive Index ◽  
Barium Titanate ◽  
Optical Trapping ◽  
Super Resolution ◽  
High Refractive Index ◽  
Trapping Efficiency ◽  
Single Beam ◽  
Imaging Performance ◽  
Super Resolution Microscopy ◽  
Optically Trapped

As water is normally used as the immersion medium in optically trapped microsphere microscopy, the high-refractive-index barium titanate glass (BTG) microsphere shows a better imaging performance than the low-index polystyrene (PS) or melamine formaldehyde (MF) microsphere, but it is difficult to be trapped by single-beam optical trapping due to its overly high refractive index. In this study, coated BTG microspheres with a PS coating have been computationally explored for the combination of optical trapping with microsphere-assisted microscopy. The PS coating thickness affects both the optical trapping efficiency and photonic nanojet (PNJ) property of the coated BTG sphere. Compared to the uncoated BTG sphere, the coated BTG sphere with a proper PS coating thickness has a highly improved trapping efficiency which enables single-beam optical trapping, and a better PNJ with a higher optical intensity Imax and a narrower full width at half maximum (FWHM) corresponding to better imaging performance. These coated BTG spheres also have an advantage in trapping efficiency and imaging performance over conventional PS and MF spheres. The coated BTG microsphere is highly desirable for optically trapped microsphere super-resolution microscopy and potentially beneficial to other research areas, such as nanoparticle detection.

Micro Flow Direction Analysis Using Gold Sputtered Planar V-Shaped Electrode Pattern

2020 ◽  
Author(s):  
Mohammad Salman Parvez ◽  
Md Fazlay Rubby ◽  
Sajid Mahfuz Ucchyash ◽  
Prosanto Biswas ◽  
Hasina Huq ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Applied Voltage ◽  
Low Voltage ◽  
Low Frequency ◽  
Electrical Impedance Spectroscopy ◽  
Sensing Element ◽  
Bulk Fluid ◽  
Sensing Mechanism ◽  
Micro Particles ◽  
Capacitive Charging

Abstract Sensing and detecting micro particles require a bulk fluid motion towards the sensing element in order to get a desirable response from the sensing element. Specially for low-concentrated fluid suspension response time is very long. So both for detection and sensing mechanism if the fluid flow is guided at a reasonable speed and at a low voltage and relatively low frequency which is suitable for bio-particles; the sensing mechanism can be enhanced largely. But sometimes it is required to re-accumulate or recombine the fluid. Previously parallel plate configuration was used to concentrate particle, but this is for the first time a V-shaped electrode pattern used to guide the bulk flow for concentration purpose. The V-shaped electrode set-up was made by following an unconventional way using sputtering machine which was cheaper than the conventional Photolithography method. AC-Electroosmosis from planar electrodes is a strong mechanism for creating micro-flows from several hundred microns away from the electrode surface. The mechanism for the AC Electroosmotic fluid flow is based on Capacitive charging which causes due to the generation of counter-ions at the electrode-electrolyte interface and Faradaic charging which is generated by the accumulation of co-ions. These two different methods are responsible for a converging and diverging surface flow of the fluid particles. At lower voltage capacitive charging method plays a significant role and most of the applied voltage drops occur at the electrical double layer but up to a certain voltage level Faradaic charging method takes over and starts dominating. The induced flow velocity by both methods has different relationship with the applied voltage. In this experiment Electrical Impedance Spectroscopy (EIS) was used to determine the suitable frequency range for the application & 2.12Vrms was used initially which is a very low voltage. An equivalent circuit for the setup was analyzed. Finally, an analysis was made on this setup using conductive fluid to observe the AC Electrothermal (ACET) effect. In our experiment the goal was to get an optimum velocity for concentration at low voltage and low frequency also to observe the guiding direction of the fluid flow in order to find a way to focus the fluid flow towards the desired direction.

Optically driven pumps and flow sensors for microfluidic systems

2008 ◽  
Vol 222 (5) ◽  
pp. 829-837 ◽  
Author(s):  
H Mushfique ◽  
J Leach ◽  
R Di Leonardo ◽  
M J Padgett ◽  
J M Cooper
Keyword(s):  
Fluid Flow ◽  
Optical Tweezers ◽  
Microfluidic Channel ◽  
Optical Traps ◽  
Spin Angular Momentum ◽  
Flow Sensors ◽  
Flow Sensing ◽  
Optically Trapped ◽  
Surrounding Fluid ◽  
Displace Fluid

This paper describes techniques for generating and measuring fluid flow in microfluidic devices. The first technique is for the multi-point measurement of fluid flow in microscopic geometries. The flow sensing method uses an array of optically trapped microprobe sensors to map out the fluid flow. The optical traps are alternately turned on and off such that the probe particles are displaced by the flow of the surrounding fluid and then retrapped. The particles' displacements are monitored by digital video microscopy and directly converted into velocity field values. The second is a method for generating flow within a microfluidic channel using an optically driven pump. The optically driven pump consists of two counter-rotating birefringent vaterite particles trapped within a microfluidic channel and driven using optical tweezers. The transfer of spin angular momentum from a circularly polarized laser beam causes the particles to rotate at up to 10 Hz. The pump is shown to be able to displace fluid in microchannels, with flow rates of up to 200 m−3 s−1 (200 fL s−1). In addition a flow sensing method, based upon the technique mentioned above, is incorporated into the system in order to map the magnitude and direction of fluid flow within the channel.

Interplay of deformability and adhesion on localization of elastic micro-particles in blood flow

2018 ◽  
Vol 861 ◽  
pp. 55-87 ◽  
Author(s):  
Huilin Ye ◽  
Zhiqiang Shen ◽  
Ying Li
Keyword(s):  
Blood Flow ◽  
Fluid Flow ◽  
Adhesion Strength ◽  
Vessel Wall ◽  
Viscous Force ◽  
Cascade Process ◽  
Micro Particles ◽  
Region I ◽  
Region Ii ◽  
Near Wall

The margination and adhesion of micro-particles (MPs) have been extensively investigated separately, due to their important applications in the biomedical field. However, the cascade process from margination to adhesion should play an important role in the transport of MPs in blood flow. To the best of our knowledge, this has not been explored in the past. Here we numerically study the margination behaviour of elastic MPs to blood vessel walls under the interplay of their deformability and adhesion to the vessel wall. We use the lattice Boltzmann method and molecular dynamics to solve the fluid dynamics and particle dynamics (including red blood cells (RBCs) and elastic MPs) in blood flow, respectively. Additionally, a stochastic ligand–receptor binding model is employed to capture the adhesion behaviours of elastic MPs on the vessel wall. Margination probability is used to quantify the localization of elastic MPs at the wall. Two dimensionless numbers are considered to govern the whole process: the capillary number $Ca$, denoting the ratio of viscous force of fluid flow to elastic interfacial force of MP, and the adhesion number $Ad$, representing the ratio of adhesion strength to viscous force of fluid flow. We systematically vary them numerically and a margination probability contour is obtained. We find that there exist two optimal regimes favouring high margination probability on the plane $Ca{-}Ad$. The first regime, namely region I, is that with high adhesion strength and moderate particle stiffness; the other one, region II, has moderate adhesion strength and large particle stiffness. We conclude that the existence of optimal regimes is governed by the interplay of particle deformability and adhesion strength. The corresponding underlying mechanism is also discussed in detail. There are three major factors that contribute to the localization of MPs: (i) near-wall hydrodynamic collision between RBCs and MPs; (ii) deformation-induced migration due to the presence of the wall; and (iii) adhesive interaction between MPs and the wall. Mechanisms (i) and (iii) promote margination, while (ii) hampers margination. These three factors perform different roles and compete against each other when MPs are located in different regions of the flow channel, i.e. near-wall region. In optimal region I, adhesion outperforms deformation-induced migration; and in region II, the deformation-induced migration is small compared to the coupling of near-wall hydrodynamic collision and adhesion. The finding of optimal regimes can help the understanding of localization of elastic MPs at the wall under the adhesion effect in blood flow. More importantly, our results suggest that softer MP or stronger adhesion is not always the best choice for the localization of MPs.

Active, Controlled Circular and Spin-Rotational Movement of Optically Trapped Airborne Micro-particles

2021 ◽  
Author(s):  
Jessica Arnold ◽  
aimable kalume ◽  
Gorden Videen ◽  
Yongle Pan ◽  
Chuji Wang
Keyword(s):  
Rotational Movement ◽  
Micro Particles ◽  
Optically Trapped

scholarly journals Raman Spectroscopy of Optically Trapped Single Biological Micro-Particles

Sensors ◽  
2015 ◽  
Vol 15 (8) ◽  
pp. 19021-19046 ◽  
Author(s):  
Brandon Redding ◽  
Mark Schwab ◽  
Yong-le Pan
Keyword(s):  
Raman Spectroscopy ◽  
Micro Particles ◽  
Optically Trapped

Real time characterization of hydrodynamics in optically trapped networks of micro-particles

2010 ◽  
Vol 3 (4) ◽  
pp. 244-251 ◽  
Author(s):  
Arran Curran ◽  
Alison Yao ◽  
Graham Gibson ◽  
Richard Bowman ◽  
Jon Cooper ◽  
...  
Keyword(s):  
Real Time ◽  
Micro Particles ◽  
Optically Trapped
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