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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.
Polydimethylsiloxane 기반 미세유체시스템의 음향열적 가열 및 응용
성형진(Hyung Jin Sung),하병항(Byunghang Ha),박진수(Jinsoo Park),굴람 데스트기르(Ghulam Destgeer),정진호(Jin Ho Jung) 한국가시화정보학회 2016 한국가시화정보학회지 Vol.14 No.1
We report a finding of fast(exceeding 2,000 K/s) heating of polydimethylsiloxane(PDMS), one of the most commonly-used microchannel materials, under cyclic loadings at high(~MHz) frequencies. A microheater was created based on the finding. The heating mechanism utilized vibration damping of sound waves, which were generated and precisely manipulated using a conventional surface acoustic wave(SAW) microfluidic system, in PDMS. The penetration depths were measured to range from 210 μm to 1290 μm, enough to cover most microchannel heights in microfluidic systems. The energy conversion efficiency was SAW frequency-dependent and measured to be the highest at around 30 MHz. Independent actuation of each interdigital transducer(IDT) enabled independent manipulation of SAWs, permitting spatiotemporal control of temperature on the microchip. All the advantages of this microheater facilitated a two-step continuous flow polymerase chain reaction(CFPCR) to achieve the billion-fold amplification of a 134 bp DNA amplicon in less than 3 min. In addition, a technique was developed for establishing dynamic free-form temperature gradients(TGs) in PDMS as well as in gases in contact with the PDMS.
박광석(Kwangseok Park),박진수(Jinsoo Park),정진호(Jin Ho Jung),굴람 데스트기르(Ghulam Destgeer),후스네인 아메드(Husnain Ahmed),라힐 아마드(Raheel Ahmad),성형진(Hyung Jin Sung) 한국가시화정보학회 2017 한국가시화정보학회지 Vol.15 No.1
In droplet-based microfluidic systems, in-droplet preconcentration of a sample is one of the important prerequisites for biochemical or medical analysis. There have been a few studies on preconcentration in a moving droplet, but they are limited to practical applications since 1) their method are time-consuming or 2) they require specific properties such as electric and magnetic properties. In this study, we demonstrated the position control of polystyrene particles of 5 and 10 μm in diameter inside a moving water-in-oil droplet using traveling surface acoustic waves. Since the frequencies for effective control of each diameter were found, microparticles with no labels could be utilized. In addition, the proposed method enabled on-demand preconcentration inside a polydimethylsiloxane microchannel. In-droplet preconcentration of microparticles was realized by splitting a mother droplet with manipulated particles at a downstream bifurcation zone. Given these advantages, the proposed system is a promising acoustofluidic lab-on-a-chip platform for preconcentration inside a droplet.