• Journal of the Korean Society for Precision Engineering
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• v.30 no.2
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• pp.236-240
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• 2013

In this presentation, we propose a fabrication method of PDMS stencil to apply into a localized culture of NIH/3T3 cells. PDMS stencil was fabricated by nitrogen gas blowing and soft lithography from preparing SU-8 master mold by photolithography. PDMS stencil pattern was production of the circle size 20 to $500{\mu}m$. In the culture test of PDMS stencil, a stencil was placed on a glass disk. The NIH/3T3 cells were successfully cultured into micropatterns by using the PDMS stencil. The results showed that cells could be cultured into micropatterns with precisely controlled manner at any shapes and specific size for bioscience study and bioengineering applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.99-100
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• 2007

Transferring patterns from mold to PDMS stamp is very useful technology in micro-fabrication, complex and three-dimensional structures. First experimentation, mold's patterns wens transferred to PDMS stamp. Comparing with PDMS stamp and Mold, patterns were transferred about 97.9%. Second experimentation, PDMS stamps were made several times by only one mold, scale and distance of transferred patterns were uniform about 89.3%. We proved that transferring patterns from mold to PDMS stamp is accurate. The uniformity of stamps is the same after mold was used several times. Transferring patterns from mold to PDMS stamp has uniformity and accuracy, it will be useful technology.

• Journal of IKEEE
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• v.20 no.2
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• pp.171-173
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• 2016

In this study, we fabricate a high efficiency heater consisting of the indium tin oxide (ITO) nanoparticle (NP)-paste and polydimethylsiloxane (PDMS) and investigate the effect of PDMS on temperature maintenance of the heater through the comparison with the PDMS-free ITO film heater. Compared to the ITO film heater, the temperature of the PDMS/ITO film heater lasts 1.5 times longer. And the power consumption of the PDMS/ITO film heater is reduced by 35%, owing to the low thermal conductivity of the PDMS layer.

• Membrane and Water Treatment
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• v.2 no.1
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• pp.39-49
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• 2011

We investigated about the utilization improvement of the PDMS and fluoropolymers by mutual application in environmental analysis. We were conducted the direct fluorination with mild condition on the PDMS films and analyzed its surfaces before and after fluorination. The results of FTIR and SEM analysis on the PDMS films showed that the film surfaces were fluorinated without irreversible deformation by the fluorination. During the fluorination, the measured contact angles of water and several alcohols on the PDMS films decreased with time and that of most alcohols decreased to 0 after 30 minutes. The surface energy of fluorinated PDMS films has increased by 2 times. Also, we investigated the influence factors on the change of permeation rate of water through PDMS tubes with time. It was observed that the change of permeation rate of water through PDMS tube was affected by temperature, water phase and spatial distribution of water. From these results, we could verify the principal causes of the decrease of permeation rate of water through PDMS tube with time and proposed a new experimental setup for reducing the variation of permeation rate of water less than 2%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.9
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• pp.720-727
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• 2008

Microfluidic single chip integrating thermopneumatic micropump and micro check valve are developed. The micropump and micorvalve are made of biocompatible materials, glass and PDMS, so as to be applicable to the biochip. By using the passive-type check valve, backward flow and fluid leakage are blocked and flow control is stable and precise. The chip is composed of three PDMS layers and a glass substrate. In the chip, flow channel and pump chamber were made on the PDMS layers by the replica molding technique and pump heater was made on the glass substrate by Cr/Au deposition. Diameter of the pump chamber is 7 mm and the width and depth of the channel are 200 and $180{\mu}m$, respectively. The PDMS layers chip and the heater deposited glass chip are combined by a jig and a clamp for pumping operation, and they are separable so that PDMS chip is used as a disposable but the heater chip is able to be used repeatedly. Pumping performance was simulated by CFD software and investigated experimentally. The performance was the best when the duty ratio of the applied voltage to the heater was 33%.

• Membrane Journal
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• v.25 no.3
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• pp.295-300
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• 2015

PDMS-NaA zeolite membranes were prepared by adding 0~40 wt% NaA zeolite. Based on SEM observation, NaA zeolite was dispersed in the PDMS-NaA zeolite membranes with $2{\sim}5{\mu}m$. The permeabilities of $H_2$ and $N_2$ gases through PDMS-NaA zeolite membranes increased as NaA zeolite contents increased and $H_2$ gas had better permeabilities than $N_2$. The selectivity ($H_2/N_2$) of PDMS-NaA zeolite membranes increased as NaA zeolite contents increased.

• Journal of the Korean Society of Food Culture
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• v.18 no.1
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• pp.69-74
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• 2003

This study was conducted to find the appropriate fiber for extraction of volatile compounds from Perilla frutescens var. acuta. by solid phase microextraction (SPME). Two SPME fiber, carboxen/polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane (PDMS) were used to determine the selectivity of the fibers to the different flavor compounds present in the Perilla frutescens var. acuta. Thirty-nine compounds were identified in the volatile compounds extracted by CAR/PDMS fiber, including 6 aldehyde, 1 alcohol, 10 hydrocarbons, 17 terpene hydrocarbons, 2 ketones and 3 benzenes. In PDMS fiber, 3 aldehydes, 2 alcohols, 13 terpene hydrocarbons and 2 miscellaneouses were identified. Perillaldehyde was found to be major volatile flavor component of fresh Perilla frutescens var. acuta. Perillaldehyde and terpene hydrocarbons were more identified in PDMS fiber. These results suggested that the selectivity of PDMS fiber was better than that of CAR/PDMS fiber in Perilla frutescens var. acuta..

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.111-118
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• 2018

In order to develop a local stiffness-variant stretchable substrate with the soft PDMS/hard PDMS/FPCB configuration consisting of two stiffness-different polydimethylsiloxane (PDMS) parts and flexible printed circuit board, a FPCB was bonded to PDMS using the acrylic-silicone double-sided tape and the interfacial adhesion of the PDMS/FPCB was evaluated. The pull strength of the FPCB, which was bonded to the fully cured PDMS using the silicone adhesive of the double-sided tape, was 259 kPa and the delamination during the pull test occurred at the interface between the PDMS and the silicone adhesive. On the contrary, the bonding process, for which the FPCB was bonded using the silicone adhesive to the PDMS partially cured for 15~20 minutes at $60^{\circ}C$ and then the PDMS was fully cured for 12 hours at $60^{\circ}C$, exhibited the remarkably enhanced pull strength of 1,007~1,094 kPa. With the above mentioned bonding process, the delamination during the pull test was observed at the interface between the FPCB and the acrylic adhesive of the acrylic-silicone double sided tape.

• Membrane Journal
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• v.23 no.6
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• pp.418-424
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• 2013

The PDMS-chitosan composite membranes were prepared by addition of 0.02~0.60 wt% chitosan to PDMS. In order to investigate the characteristics of these membranes, we used the analytical methods such as SEM and TGA. Gas permeation experiments was performed in $30^{\circ}C$, $4kg/cm^2$, the permeability and selectivity of $H_2$ and $N_2$ according to content change in composite membrane were investigated. The permeability of $H_2$ and $N_2$ for the PDMS-chitosan composite membranes increased when 0~0.20 wt% chitosan was added, and then decreased at higher wt% as chitosan content increased. The selectivity ($H_2/N_2$) of PDMS-chitosan composite membranes decreased when 0~0.20 wt% chitosan was added, and then increased as chitosan content increased. In the case of PDMS-chitosan in which chitosan was inserted to PDMS, thermal stability of PDMS was enhanced. Based on SEM observation, as the chitosan content within PDMS increased, the surface of the composite membranes became coarse and began to form holes.

• Membrane Journal
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• v.19 no.1
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• pp.54-62
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• 2009

Pervaporation membrane for butanol separation was prepared by hybrid process. Plasma treatment of commercial poly(dimethylsiloxane) (PDMS) membrane was attempted and combination of plasma treatment and PDMS solution coating on polysulfone, poly(ether imide) supports were also performed. Plasma treatment of PDMS membrane with hexane and silane group compounds was performed to increase the hydrophobicity of the surface, which enhanced the separation factor upto 12.5 at the expense of flux decrease down to $1.15kg/m^2{\cdot}hr$. Contact angle and relative sorption ratio were also related with hydrophobicity of the memrbane. Increase of PDMS prepolymer composition resulted in dense structure of coating layer with better separation factor. Effects of sequence of PDMS coating vs. plasma treatment were examined. It was found that plasma treatment with butanol and n-hexane plasma followed by PDMS coating showed better performance and vice versa for plasma treatment with hexamethyldisilane and hexamethyldisilazane.