• 센서학회지
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• 제29권6호
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• pp.399-406
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• 2020

Pd nanogap hydrogen sensors were developed using an elastomeric substrate and operated through an on-off mechanism. A 10 nm thick Pd thin film was formed on a polydimethylsiloxane (PDMS) substrate, and 50% of the physical strain was applied in the longitudinal direction to fabricated uniform nanogaps. The initial concentration of the hydrogen gas for the PDMS/Pd films was controlled, and subsequently, the on-off switching response was measured. We found that the average nanogap was less than 50 nm, and the Pd nanogap hydrogen sensors operated over a wide range of temperatures. In particular, the sensors work properly even at a very low temperature of -40℃ with a fast response time of 2 s. In addition, we have investigated the relative humidity and annealing effects.

• 한국가시화정보학회지
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• 제21권3호
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• pp.15-22
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• 2023

This research introduces an innovative approach for fabricating microstructure surfaces using spray-coating deposition. The resulting surface, referred to as Magnetically Responsive Microstructures (MRM), exhibits hierarchically structured micro-pillar arrays with remarkably high aspect ratios. The fabrication process involves precisely mixing PDMS and hexane with Carbonyl iron powders, followed by ultrasonication and spray-coating on the top of a PDMS substrate placed on the neodymium magnet. The MRM surface shows hydrophobic properties, characterized by a contact angle surpassing 150° and an aspect ratio exceeding 10. Through a comprehensive exploration of critical parameters, including spray amount, magnet-substrate distance, and solution ratio enhanced dynamic tunability and exceptional hydrophobic characteristics are attained. This novel approach holds significant potential for diverse applications in the realm of dynamically tunable microstructures and magnetically responsive surfaces.

• 대한전자공학회논문지SD
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• 제48권6호
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• pp.7-14
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• 2011

본 논문은 PDMS(polydimethyl siloxane) 스탬프를 이용한 원통형 마이크로 접촉인쇄(roll-type micro-contact printing)에 관한 것으로 대면적 플라스틱 기판에 미세 금속 전극 인쇄를 PDMS 스탬프의 평탄화, 은 나노 잉크의 은 함량, 공정변수인 코팅속도, 잉킹속도, 프린팅속도, 프린팅 압력을 조절하여 가장 우수한 인쇄특성을 나타내는 조건을 도출하였다. 그 결과 면적 $4.5cm\;{\times}\;4.5cm$ 기판에 최소선폭 10 um, 두께 300 nm, 표면거칠기 40 nm 이하, 비저항 $2.08\;{\times}\;10^{-5}{\Omega}{\cdot}cm$의 특성을 갖는 은미세 전극을 인쇄하였다.

• Journal of Mechanical Science and Technology
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• 제19권2호
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• pp.649-654
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• 2005

This paper presents fabrication and drive test of a peristaltic PDMS micropump actuated by the thermopneumatic force. The micropump consists of the three peristaltic-type actuator chambers with microheaters on the glass substrate and a microchannel connecting the chambers and the inlet/outlet port. The micropump is fabricated by the spin-coating process, the two-step curing process, the JSR (negative PR) molding process, and etc. The diameter and the thickness of the actuator diaphragm are 2.5 mm and $30{\mu}m$, respectively. The meniscus motion in the capillary tube is observed with a video camera and the flow rate of the micro pump is calculated through the frame analysis of the recorded video data. The maximum flow rate of the micropump is about $0.36\;{\mu}L/sec$ at 2 Hz for the zero hydraulic pressure difference when the 3-phase input voltage is 20 V.

• 센서학회지
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• 제27권6호
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• pp.392-396
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• 2018

Structural color has many advantages over pigment based color. In recent years, researches are being conducted to apply these advantages to applications such as wearable devices. In this study, strain sensor, a kind of wearable device, was developed using structural color. The use of structural color has the advantage of not using energy and complex measuring equipment to measure strain rate. Wrinkle structure was fabricated on the surface of Poly-dimethylsiloxane (PDMS) and used it as a sensor which color changes according to the applied strain. In addition, a transmittance-changing sensor was developed and fabricated by synthesizing additional glass nanoparticles. Furthermore, a strain sensor was developed that is largely transparent at the target strain and opaque otherwise.

• 한국음향학회지
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• 제38권4호
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• pp.459-466
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• 2019

투명한 PMMA (Poly methyl methacrylate) 기판 위에 탄소나노튜브(Carbon Nanotube, CNT)와 PDMS (Poly dimethylsiloxane)를 코팅한 복합체에 레이저 펄스를 조사하면 열탄성효과에 의해 수중에 강한 초음파가 발생한다. 본 논문에서는 그 초음파 발생과 관련한 열음향 이론을 정립하고, 가우시안 파형을 갖는 레이저 펄스를 두께가 $20{\mu}m$인 CNT/PDMS 복합체에 조사했을 때 어떤 파형의 초음파가 발생하는지를 시뮬레이션을 통해 파악하였다. 그 결과로부터 CNT/PDMS 복합체에서는 충격 초음파가 발생하며, 그 파의 형상은 복합체의 각종 물성 값이 ${\pm}20%$ 변하여도 크게 변하지 않는 것을 확인하였다. 그러나 정(+), 부(-)의 피크 값은 열팽창계수가 증가하거나 밀도, 열용량, 음속이 감소하면 증가하며, 열전도도에 대해서는 민감하게 변하지 않음을 알았다. 나아가, 직접 제작한 CNT/PDMS 복합체에서 방사되는 초음파의 측정 결과와 시뮬레이션 결과의 비교로부터 그 물성 값을 추정할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.223-223
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• 2012

Surface engineering plays a significant role in fabricating highly functionalized materials applicable to industrial and biomedical fields. Surface wrinkles and folds formed by ion beam or plasma treatment are buckling-induced patterns and controlled formation of those patterns has recently gained considerable attention as a way of creating well-defined surface topographies for a wide range of applications. Surface wrinkles and folds can be observed when a stiff thin layer attached to a compliant substrate undergoes compression and plasma treatment is one of the techniques that can form stiff thin layers on compliant polymeric substrates, such as poly (dimethylsiloxane) (PDMS). Here, we report two effective methods using plasma modification techniques for controlling the formation of surface wrinkles and folds on flat or patterned PDMS substrates. First, we show a method of creating wrinkled diamond-like carbon (DLC) film on grooved PDMS substrates. Grooved PDMS substrates fabricated by a molding method using a grooved master prepared by photolithography and a dry etching process were treated with argon plasma and subsequently coated with DLC film, which resulted in the formation of wrinkled DLC film aligning perpendicular to the steps of the pre-patterned ridges. The wavelength and the amplitude of the wrinkled DLC film exhibited variation in the submicron- to micron-scale range according to the duration of argon plasma pre-treatment. Second, we present a method for controlled formation of folds on flat PDMS substrates treated with oxygen plasma under large compressive strains. Flat PDMS substrates were strained uniaxially and then treated with oxygen plasma, resulting in the formation of surface wrinkles at smaller strain levels, which evolved into surface folds at larger strain levels. Our results demonstrate that we can control the formation and evolution of surface folds simply by controlling the pre-strain applied to the substrates and/or the duration of oxygen plasma treatment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.369-369
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• 2016

A nanostructure composite is a highly suitable substance for photoacoustic ultrasound generation. This allows an input laser beam (typically, nanosecond pulse duration) to be efficiently converted to an ultrasonic output with tens-of-MHz frequency. This type of energy converter has been demonstrated by using a carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite film that exhibit high optical absorption, rapid heat transition, and mechanical durability, all of which are necessary properties for high-amplitude ultrasound generation. In order to develop the CNT-PDMS composite film, a high-temperature chemical vapor deposition (HTCVD) method has been commonly used so far to grow CNT and then produce a CNT-PDMS composite structure. Here, instead of the complex HTCVD, we use a mixed solution of hydrophobic multi-walled CNT and dimethylformamid (DMF) and fabricate a solution-processed CNT-PDMS composite film over a spherically concave substrate, i.e. a focal energy converter. As the solution process can be applied over a large area, we could easily fabricate the focal transmitter that focuses the photoacoustic output at the moment of generation from the CNT-PDMS composite layer. With this method, we developed photoacoustic energy converters with a large diameter (>25 mm) and a long focal length (several cm). The lens performance was characterized in terms of output pressure amplitude for an incident pulsed laser energy and focal spot dimension in both lateral and axial. Due to the long focal length, we expect that the new lens can be applied for long-range ultrasonic treatment, e.g. biomedical therapy.

• 마이크로전자및패키징학회지
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• 제21권4호
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• pp.125-131
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• 2014

웨어러블 패키징용 신축성 기판을 개발하기 위해 투명한 PDMS인 Sylgard 184와 검정색 PDMS인 Sylgard 170에 대해 base/curing agent 혼합비에 따른 탄성계수의 변화거동을 분석하였다. Sylgard 184와 Sylgard 170의 공칭응력-공칭변형률 곡선에서 구한 공칭탄성계수에 비해 진응력-진변형률 관계로부터 구한 진탄성계수가 2배 이상 높았으며, 진탄성계수와 공칭탄성계수의 차이는 PDMS의 강성도가 높아질수록 증가하였다. Sylgard 184에서는 base/curing agent의 혼합비가 10일 때 탄성계수의 최대값을 얻을 수 있었으며, 이때 공칭탄성계수는 1.74 MPa, 진탄성계수는 3.57 MPa이었다. Sylgard 170에서는 base/curing agent 혼합비가 2일 때 탄성계수가 최대가 되었으며, 이때 공칭탄성계수와 진탄성계수는 각기 1.51 MPa와 3.64 MPa이었다.

• Applied Science and Convergence Technology
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• 제27권1호
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• pp.5-8
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• 2018

In this paper, plasma treatment effects on a ploy(dimethyl siloxane) substrate were analyzed for the applications of stretchable silver nanowire (Ag NWs) electrodes. The oxygen plasma treated sample shows the best performance compared to nitrogen treated and untreated samples. The lowest sheet resistance and reasonable stretching capability was achieved up to 20% strain condition without open circuit fail for the oxygen plasma treated sample.