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High frequency travelling surface acoustic waves for microparticle separation
Ghulam Destgeer,Anas Alazzam,성형진 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.9
In this study, we have demonstrated a particle separation device taking advantage of the high frequency sound waves. The sound waves, in the form of surface acoustic waves, are produced by an acoustofluidic platform built on top of a piezoelectric substrate bonded to a microfluidic channel. The particles’ mixture, pumped through the microchannel, is focused using a sheath fluid. A Travelling surface acoustic wave (TSAW), propagating normal to the flow, interacts with the particles and deflects them from their original path to induce size-based separation in a continuous flow. We initially started the experiment with 40 MHz TSAWs for deflecting 10 µm diameter polystyrene particles but failed. However, larger diameter particles (~ 30 µm) were successfully deflected from their streamlines and separated from the smaller particles (~ 10 µm) using TSAWs with 40 MHz frequency. The separation of smaller diameter particles (3, 5 and 7 µm) was also achieved using an order of magnitude higher-frequency (~ 133 MHz) TSAWs.
Destgeer, Ghulam,Jung, Jin Ho,Park, Jinsoo,Ahmed, Husnain,Sung, Hyung Jin American Chemical Society 2017 ANALYTICAL CHEMISTRY - Vol.89 No.1
<P>A sessile droplet of water carrying polystyrene rnicropartides of different diameters was uniformly exposed to high frequency surface acoustic waves (SAWS) produced by an interdigitated transducer (IDT). We investigated the concentration behavior of the microparticles as the SAWS generated a strong acoustic streaming flow (ASF) inside the water droplet and exerted a direct acoustic radiation force (ARF) on the suspended particles, the magnitude of which depended upon the particle diameter. As a result of the ARF, the micropartides were concentrated according to their diameters at different positions inside the sessile droplet placed in the path of the SAW, right in front of the IDT. The micropartide concentration behavior changed as the sessile droplet contact angle with the substrate was varied by adding surfactant to the water or by gradually evaporating the water. The positions at which the smaller and larger micropartides were concentrated remained distinguishable, even at very different experimental conditions. The long-term exposure of the droplets to the SAWS was accompanied by the gradual evaporation of the carrier fluid, which dynamically changed the droplet contact angle as well as the concentration of particles. Complete evaporation of the fluid left behind several concentrated yet separated clusters of particles on the substrate surface. The effect of the droplet contact angle on particles' concentration behavior and consequent separation of particles has been uniquely studied in this SAW-based report.</P>
Submicron separation of microspheres via travelling surface acoustic waves.
Destgeer, Ghulam,Ha, Byung Hang,Jung, Jin Ho,Sung, Hyung Jin Royal Society of Chemistry 2014 Lab on a chip Vol.14 No.24
<P>Submicron separation is the segregation of particles having a diameter difference of less than one micrometre. We present an acoustofluidic particle separator with submicron separation resolution to study the continuous, label-free, and contactless separation of polystyrene (PS) particles based on their acoustofluidic parameters such as size, density, compressibility and shape. In this work, the submicron separation of PS microspheres, having a marginal size difference, is achieved inside a polydimethylsiloxane (PDMS) microfluidic channel via travelling surface acoustic waves (TSAWs). The TSAWs of different frequencies (200, 192, 155, and 129 MHz), propagating normal to the fluid flow direction inside the PDMS microchannel, realized continuous separation of particles with a diameter difference as low as 200 nm. A theoretical framework based on the rigid and elastic theories is presented to support the experimental results.</P>
Particle concentration inside a sessile drop using surface acoustic waves
Ghulam Destgeer(데스트기르 굴람),Hyunjun Cho(조현준),Hyung Jin Sung(성형진) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
We have investigated concentration of polystyrene particles inside a sessile drop, placed on top of a piezoelectric substrate, actuated by surface acoustic waves (SAWs). The particles are exposed to various combinations of forces – acoustic streaming flow (ASF) based drag force, travelling or standing SAW based acoustic radiation force (ARF), and centrifugal force. We have identified four distinct modes of polystyrene particle concentration that depend upon particle diameter, SAW frequency, acoustic wave field, acoustic waves’ attenuation length, and droplet volume. Numerical simulations are performed to visualize the ASF flow field inside the sessile drop, and determine its effects on the particle motion. Different SAW actuation frequencies (10-133 ㎒) and several particle diameters (1-30 ㎛) are tested.
Destgeer, Ghulam,Ha, Byung Hang,Park, Jinsoo,Jung, Jin Ho,Alazzam, Anas,Sung, Hyung Jin American Chemical Society 2015 ANALYTICAL CHEMISTRY - Vol.87 No.9
<P>We demonstrate a miniaturized acoustofluidic device composed of a pair of slanted interdigitated transducers (SIDTs) and a polydimethylsiloxane microchannel for achieving size-selective separation and exchange of medium around polystyrene particles in a continuous, label-free, and contactless fashion. The SIDTs, deposited parallel to each other, produce tunable traveling surface acoustic waves (TSAWs) at desired locations, which, in turn, yield an anechoic corner inside the microchannel that is used to selectively deflect particles of choice from their streamlines. The TSAWs with frequency <I>f</I><SUB>R</SUB> originating from the right SIDT and propagating left toward the microchannel normal to the fluid flow direction, laterally deflect larger particles with diameter <I>d</I><SUB>1</SUB> from the hydrodynamically focused sample fluid that carries other particles as well with diameters <I>d</I><SUB>2</SUB> and <I>d</I><SUB>3</SUB>, such that <I>d</I><SUB>1</SUB> > <I>d</I><SUB>2</SUB> > <I>d</I><SUB>3</SUB>. The deflected particles (<I>d</I><SUB>1</SUB>) are pushed into the top-left corner of the microchannel. Downstream, the TSAWs with frequency <I>f</I><SUB>L</SUB>, such that <I>f</I><SUB>L</SUB> > <I>f</I><SUB>R</SUB>, disseminating from the left SIDT, deflect the medium-sized particles (<I>d</I><SUB>2</SUB>) rightward, leaving behind the larger particles (<I>d</I><SUB>1</SUB>) unaffected in the top-left anechoic corner and the smaller particles (<I>d</I><SUB>3</SUB>) in the middle of the microchannel, thereby achieving particle separation. A particle not present in the anechoic corner could be deflected rightward to realize twice the medium exchange. In this work, the three-way separation of polystyrene particles with diameters of 3, 4.2, and 5 μm and 3, 5, and 7 μm is achieved using two separate devices. Moreover, these devices are used to demonstrate multimedium exchange around polystyrene particles ∼5 μm and 7 μm in diameter.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancham/2015/ancham.2015.87.issue-9/acs.analchem.5b00525/production/images/medium/ac-2015-00525e_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ac5b00525'>ACS Electronic Supporting Info</A></P>