• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제50권3호
• /
• pp.136-143
• /
• 2001

A micro particle manipulator, which is devised for trapping particles at fixed positions by negative dielectrophoretic force (DEP force), has been fabricated and experimented. It is composed of square type electrode arrays fabricated by nickel electroplating with the height of 28 ${\mu}m$. To improve the quality of electroplated nickel electrodes, plating conditions have been optimized. Micro particles used in this study are polystyrene spheres and their to the specific position and trapped. The DEP force along the moving path of the particles has been estimated by the motion equation of a single particle. The displacement of a particle with an elapsed time was measured using a high-speed camera (1000 frames/sec). The velocity and acceleration of the particle were calculated from the measured data. The DEP force acting on the particle was estimated.

• 분석과학
• /
• 제29권5호
• /
• pp.225-233
• /
• 2016

입자 표면에 고분자를 화학적으로 접목하는 것은 수용성 액체 이상 시스템(ATPS)과 같이 분리된 액체 층에서 마이크로/나노입자를 선택적으로 분배시키는데 중요한 구실을 한다. 본 연구에서는 덱스트란, 폴리에틸렌 글리콜, 알부민을 화학적으로 폴리스티렌 자성 마이크로입자 표면에 화학적으로 부착시켰다. 분배 현상을 역전시킬 수 있는 긴 고분자 사슬의 부착은 일차 아민 작용기를 가진 다양한 고분자를 p-톨루엔술폰산(토실)기를 부착시킨 폴리스티렌 자성 마이크로입자와의 S_N2 치환에 의해 간단히 수행될 수 있었다. 이 후 적외선 현미경을 사용하여 마이크로입자의 표면 변화의 유무를 검사하였다. 반응 후 입자들은 세 가지 폴리머 모두 N-H 신축 진동 피크를 보였으며 대부분의 주요 피크들의 위치는 반응 전후에 유사하였으나 지문 영역에서 구별 가능한 차이를 보였다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제23권3호
• /
• pp.10-13
• /
• 2021

The method of removing micro-plastics from sea water has been developed using electro-magnetic force. Plastics are difficult to decompose and put a great load on the marine environment. Especially a plastic with a size of 5 mm or less is defined as micro-plastic and are carried by ocean currents over long distances, causing global pollution. These are not easily decomposed in the natural environment. The Lorentz force was generated in simulated sea water and its reaction force was applied to the micro-plastic to control their motion. Lorentz force was generated downward and the reaction force to the plastics was upward. The plastic used in the experiment was polystyrene with a diameter of 6 mm, and the density was 1.07 g/cm³. The polystyrene sphere levitated at the current density of 0.83 A/cm² and the external field of 0.87T. The particle trajectory calculation was also made to design separation system using superconducting magnet.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2007년도 추계학술대회
• /
• pp.55-58
• /
• 2007

To improve the conventional optical chromatography, the continuous particle separator, the cross-type optical chromatography, is fabricated using micro-channel and fiber optics. A laser beam irradiates into the liquid solution containing particles in the perpendicular to the liquid flow direction. The different sized polystyrene latex micro-spheres, $2.0\;{\mu}m\;{\pm}\;0.02\;{\mu}m$, $5.0\;{\mu}m\;{\pm}\;0.05\;{\mu}m$, and $10.0\;{\mu}m\;{\pm}\;0.09\;{\mu}m$ diameter, are separated in cross-type optical chromatography. The separated particles are delivered to down stream in the micro-channel maintaining the retention distance continuously. The measured retention distances for different sized particles well agree with theoretical predictions.

• 대한기계학회논문집A
• /
• 제32권4호
• /
• pp.297-302
• /
• 2008

We present an electrical particle velocity profiler using particle transit time across uneven inter-gap electrodes. We measure both the particle position and velocity from the voltage signals generated by the particles passing across sensing electrodes, thus obtaining the velocity profile of the particles in a microfluidic channel. In the experimental study, we use polystyrene microparticles to characterize the performance of the electrical particle velocity profiler. The particle velocity profile is measured with the uncertainty of 5.44%, which is equivalent to the uncertainty of 5% in the previous optical method. We also experimentally demonstrate the capability of the present method for in-channel clogging detection. Compared to the previous optical methods, the present electrical particle velocity profiler offers the simpler structure, the cheaper cost, and the higher integrability to micro-biofluidic systems.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권6호
• /
• pp.305-311
• /
• 2004

Charge transport phenomena of polyaniline-DBSA/High Impact Polystyrene (PAM-DBSA/HIPS) blends have been studied through an examination of electrical conduction. HIPS used host polymer in the blends and PANI-DBSA obey a space charge limited conduction mechanism and a ohmic conduction mechanism respectively. However, PANI-DBSA/HIPS blends do not obey any classical conduction mechanism. Analysis of conduction mechanism revealed that the charging current of PANI-DBSA/HIPS blends increased with the increase of PANI-DBSA content. This result migrlt be explained by the reduction in the distance between PANI-DBSA particles enabling the charge carriers to migrate from a chain to a neighboring chain via hopping or micro tunneling. It was also found that the charging current of PANI-DBSA/HIPS blends decreased as the temperature was elevated, which is of typical phenomena in metals. It is speculated that the charge transport in PANI-DBSA particle was somewhat constrained due to strong phonon scattering.

• 한국응용과학기술학회지
• /
• 제27권3호
• /
• pp.240-248
• /
• 2010

The blending effects of surfactants on the polystyrene emulsion polymerization were studied. The blending of Triton X-100 and SDS affects to the interfacial properties of the styrene monomer and water phases, and finally, the properties of the polystyrene latex particles. As the blending ratio of SDS/Triton X-100 increases, the interfacial tension and CMC of the blended surfactants were decreased and results in a reducing the size of the latex particles. It was found that the interfacial tension was reduced when the surfactant were blended. By increasing the SDS content, the interfacial tension was reduced, and, at a certain condition, the interfacial tension was reached to an extremely low value to form micro-emulsion and the nano-sized latex particles (80~110 nm).

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2004년도 Proceedings of 2004 Korea-Japan Joint Seminar on Particle Image Velocimetry
• /
• pp.91-110
• /
• 2004

A comprehensive three-dimensional nano-particle tracking technique in micro- and nano-scale spatial resolution using the Total Internal Reflection Fluorescence Microscope (TIRFM) is discussed. Evanescent waves from the total internal reflection of a 488nm argon-ion laser are used to measure the hindered Brownian diffusion within few hundred nanometers of a glass-water interface. 200-nm fluorescence-coated polystyrene spheres are used as tracers to achieve three-dimensional tracking within the near-wall penetration depth. A novel ratiometric imaging technique coupled with a neural network model is used to tag and track the tracer particles. This technique allows for the determination of the relative depth wise locations of the particles. This analysis, to our knowledge is the first such three-dimensional ratiometric nano-particle tracking velocimetry technique to be applied for measuring Brownian diffusion close to the wall.

• 대한의용생체공학회:의공학회지
• /
• 제34권4호
• /
• pp.189-196
• /
• 2013

Dielectrophoresis(DEP) is useful in manipulation and separation of micro-sized particles including biological samples such as bacteria, blood cells, and cancer cells in a micro-fluidic device. Especially, those separation and manipulation techniques using DEP in combination of micro fabrication technique have been researched more and more. Recently, it is revealed that a window structure of insulating layer in microfluidic DEP chip is key role in trap of micro-particles around the window structure. However, the trap phenomenon-driven by DEP force gradient did not fully understand and is still illusive. In this study, we characterize the trap mechanism and efficiency with different shapes of window in a microfluidic DEP chip. To do this characterization, we fabricated 4 different windows shapes such as rhombus, circle, squares, and hexagon inside a micro-fluidic chip, and performed micro-sized particles manipulation experiments as varying the frequency and voltage of AC signal. Moreover, the numerical simulation with the same parameters that were used in the experiment was also performed in order to compare the simulation results and the experimental results. Those comparison shows that both results are closely matched. This study may be helpful in design and development of microfluidic DEP chip for trapping micro-scaled biological particle.

• 센서학회지
• /
• 제20권5호
• /
• pp.357-362
• /
• 2011

This paper demonstrates a novel electrodynamic technique to remove particles from the wall of microchannels. Dielectrohporesis(DEP) is generated by applying alternating electric potentials to the interdigitated electrodes integrated at the bottom of the micro-channel. The proposed technique is applied to a general microfluidic channel as a feasibility test. To examine the wall loss reduction efficiency, 10 ${\mu}m$ diameter Polystyrene latexes(PSL) were supplied to the inlet of the device. Then, the concentration of collected particles through devices was measured. In the experiment for 10 ${\mu}m$ diameter PSL particles, the concentration of the injected particles was $174.25{\times}10^4$ particles/ml. However, the concentration of collected particles at the outlet was $52.25{\times}10^4$ particles/ml. Only 30 % of particles had arrived at the outlet and 70 % of particles had adhered to the wall of the microfluidic channel. By applying alternating electric potentials from 0 to 20 $V_{pp}$ at 3 MHz, the concentration of injected particles was 135.00${\times}10^4$ particles/ml, the concentration of collected particles was increased as $105.25{\times}10^4$ particles/ml at 20 $V_{pp}$ at the outlet. When the electric potential was 20 $V_{pp}$, the particle loss was decreased by 39 % (initial loss: 70 %, loss at 20 Vpp: 31 %) with 10 ${\mu}m$ particle. The particle loss was decreased along to the incensement of electric potentials and the enlargement of the diameter of particles. According to these measured results, it was confirmed that the proposal of using DEP technique could be a good candidate for particle loss reduction in micro-particle processing chip application. Moreover, it is expected that the proposed technique could enhance performance of microfluidic and biochip devices.