• Journal of the Microelectronics and Packaging Society
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• v.24 no.3
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• pp.19-26
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• 2017

Stretchable deformation-resistance characteristics of Au, Pt, and Cu films were measured for the stretchable packaging structure where a parylene F was used as an intermediate layer between a PDMS substrate and a metal thin film. The 150 nm-thick Au and Pt films, sputtered on the parylene F-coated PDMS substrate, exhibited the initial resistances of $1.56{\Omega}$ and $5.53{\Omega}$, respectively. The resistance increase ratios at 30% tensile strain were measured as 7 and 18 for Au film and Pt film, respectively. The 150 nm-thick Cu film, sputtered on the parylene F-coated PDMS substrate, exhibited a very poor stretchability compared to Au and Pt films. Its resistance was initially $18.71{\Omega}$, rapidly increased with applying tensile deformation, and finally became open at 5% tensile strain.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.4
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• pp.39-46
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• 2019

A stiffness-gradient soft PDMS/hard PDMS/FPCB stretchable package of the island-bridge structure was processed using the polydimethylsiloxane (PDMS) as the base substrate and the more stiff flexible printed circuit board (FPCB) as the island substrate, and its effective elastic modulus and stretchable deformation characteristics were analyzed. With the elastic moduli of the soft PDMS, hard PDMS, and FPCB to be 0.28 MPa, 1.74 MPa, and 1.85 GPa, respectively, the effective elastic modulus of the soft PDMS/hard PDMS/FPCB package was analyzed as 0.58 MPa. When the soft PDMS of the soft PDMS/hard PDMS/FPCB package was stretched to a tensile strain of 0.3, the strains occurring at hard PDMS and FPCB were found to be 0.1 and 0.003, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.4
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• pp.55-62
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• 2019

Stiffness-gradient stretchable electronic packages of the soft PDMS/hard PDMS/FPCB structure were processed using the polydimethylsiloxane (PDMS) as the base substrate and the more stiff flexible printed circuit board (FPCB) as the island substrate. The elastic characteristics of the stretchable packages were estimated and their long-term reliabilities on stretching cycles and bending cycles were characterized. With 0.28 MPa, 1.74 MPa, and 1.85 GPa as the elastic moduli of the soft PDMS, hard PDMS, and FPCB, respectively, the effective elastic modulus of the soft PDMS/hard PDMS/FPCB package was estimated as 0.6 MPa. The resistance of the stretchable packages varied for 2.8~4.3% with stretching cycles ranging at 0~0.3 strain up to 15,000 cycles and for 0.9~1.5% with 15,000 bending cycles at a bending radius of 25 mm.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.91-98
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• 2015

In order to apply to stretchable electronics packaging, locally stiffness-variant stretchable substrates consisting of island structure were fabricated by combining two polydimethylsiloxane elastomers of different stiffnesses and their elastic moduli were characterized as a function of the width of the high-stiffness island. The low-stiffness substrate matrix and the embedded high-stiffness island of the stretchable substrate were formed by using Dragon Skin 10 of the elastic modulus of 0.09 MPa and Sylgard 184 of the elastic modulus of 2.15 MPa, respectively. A stretchable substrate was fabricated to be a configuration of 6.5-cm length, 0.4-cm thickness, and 2.5-cm width, in which a high-stiffness Sylgard 184 island, of 4-cm length, 0.2-cm thickness, and 0.5~1.5-cm width, was embedded. The elastic modulus of a stretchable substrate was increased from 0.09 MPa to 0.16 MPa by incorporating the Sylgard 184 island of 0.5-cm width to Dragon Skin 10 substrate matrix. The elastic modulus was further improved to 0.18 MPa and 0.2 MPa with increasing the Sylgard 184 island width to 1.0 cm and 1.5 cm, which were in good agreement with values estimated by combining the Voigt structure of isostrain and the Reuss structure of isostress.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.239.1-239.1
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• 2016

본 연구에서는 stretchable OLED를 구현하기 위해 배선 전극으로 사용 가능한 반투명 스트레처블 Ag 전극의 특성을 연구하였다. 스트레처블 Ag 전극은 Polydimethylsiloxane(PDMS) 기판을 사용하였으며, UV 처리를 통해 wavy패턴을 가지는 PDMS 기판을 제작하여 신축성을 향상시키고, 이를 일반 PDMS 기판과 비교하였다. 만들어진 두 종류의 PDMS 기판 위에 연성과 전성의 특성을 지닌 Ag를 sputtering방법을 이용하여 두께 변수로 제작하였고 전극의 전기적, 광학적, 표면적, 기계적 특성에 대한 평가를 진행하였다. 최적화된 반투명 스트레처블 Ag 전극은 가해진 strain에 따라 투과도가 변화하여 30%의 strain을 가한 상태에서 30%의 광투과율을 보였으며, 일반 PDMS기판을 적용한 전극보다 더 낮은 저항변화율을 나타냄을 알 수 있었다. 또한 다양한 신축성 테스트(Strain test, Hysteresis test, Dynamic fatigue test)와 Field Emission Scanning Electron Microscope(FE-SEM)분석법을 통해 wavy패턴이 있는 PDMS 기판을 적용한 Ag 전극이 일반 PDMS 기판을 적용한 Ag 전극보다 더 높은 신축성을 가지는 것을 확인하였다. 이를 통해 반투명 스트레처블 Ag 전극이 차세대 stretchable OLED용 배선전극으로 적용될 가능성을 확인하였다.

• The Research Journal of the Costume Culture
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• v.11 no.3
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• pp.447-457
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• 2003

The shape of womens breast is the most important part of body silhouette. For the high-fitted clothes, in particular, more refined brassiere effective enough to show the beautiful line of female breast is asked. This study focuses on comparing the difference of the two different textiles of brassiere as to their effectiveness as a brassiere. The Stockman Lingerie Mannequin made by England is used for the draping method for the brassiere pattern. Two different brassieres of stretchable and unstretchable(cotton) textiles respectively were made out of this pattern, and the difference of effectiveness wearing the two brassieres was compared. 30 females ranging in the ages of 19 through 24, and whose size is 75A were selected as the test group who are to wear them. The result of each measurement proves that the cotton brassiere is more effective than the stretchable brassiere as a whole considering center concentration of breast, projection of breast, and bust up function. The result of the test on satisfaction of wearing brassiere was also in favor of cotton brassiere as to projection effect, bust up effect, making a good shape of bust. For the cup, in particular, unstretchable textile is more effective for making a breast look better.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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• pp.609-614
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• 2017

The proposed stretchable transparent electrodes based on silver nanowires (AgNWs) were prepared on a polyurethane (PU) substrate. In order toavoid the surface roughness caused by the silver nanowires, a titanium oxide ($TiO_2$) buffer layer was addedby coating and heating the organometallic sol-gel solution. The fabricated stretchable electrodes showedan electrical sheet resistance of $24{\Omega}sq^{-1}$, 78% transmittance at 550 nm, and an average surface roughness below 5 nm. Furthermore, the AgNW-based electrode maintained its initial electrical resistance under 130% strain testing conditions, without the assistance of additional conductive polymer layers. In this paper, the critical role of the $TiO_2$ buffer layer between the AgNW network and the PU substrate has been discussed.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.183.1-183.1
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• 2016

Due to the latest research trend toward wearable energy devices, transparent and stretchable supercapacitors which can sustain their performance even under physical deformation have steadily attracted huge attention. Despite the Ag NW is the most promising candidate for fabrication of transparent and stretchable electronics, the electrochemical instability interrupts its application to development of the energy device. Here, we introduce a transparent and highly stretchable supercapacitor made by Au-Ag core shell NW network percolation electrode. The Au-Ag core shell NW synthesized by a simple solution process not only shows excellent electrical conductivity but also greatly enhanced chemical and electrochemical stability compare to pristine Ag NW. These outstanding properties of the Au-Ag core shell NW are attributed both to the core Ag NW and the Au protecting sheath layer. The proposed Au-Ag core shell NW based supercapacitor exhibits optical transmittance with outstanding mechanical stability withstanding 60% strain without any decrease of the performance. The supercapacitors connected in series are charged and discharged stable in 30% strain turning on a red LED. These notable results demonstrate the potential of the Au-Ag core shell NW as a strong candidate for development of wearable energy devices.

• Composites Research
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• v.33 no.2
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• pp.50-54
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• 2020

Soft robotics and wearable devices require large motions and flexibility. In this regard, there is a demand for developing stretchable strain sensors which can be attached to the soft robots and wearable devices. In this work, we fabricated stretchable and electrically conductive composite fibers by combining polyurethane (PU) and silver nanoflowers (AgNFs). The PU/AgNF composite fibers showed the change of the resistance as a function of the applied strain, demonstrating the potential for stretchable strain sensors in soft robotics and wearable devices. The mechanical and electrical characteristics of the composite fibers were measured and analyzed to use the composite fibers for stretchable strain sensors.

• Elastomers and Composites
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• v.58 no.1
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• pp.11-16
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• 2023

Electronic skin (e-skin), devices that are mounted on or attached to human skin, have advanced in recent times. Yet, the development of a power supply for e-skin remains a challenge. A stretchable thermoelectric generator is a promising power supply for the e-skin patches. It is a safe and semi-permanent energy harvesting device that uses body heat for generating power. Carbon nanotube (CNT) clays are used in energy-harvesting e-skin patches. In this study, we report improved thermoelectric performance of CNT clays by using chemical doping and physical blending of thermoelectric enhancers. The n-type and p-type thermoelectric enhancers increase electrical conductivity, leading to increased power factors of the thermoelectric CNT clays. The blend of CNT clays and enhancers is intrinsically stretchable up to 50% while maintaining its thermoelectric property.