title: Photolithography-Based Patterning of Liquid Metal Interconnects for Monolithically Integrated Stretchable Circuits.
abstract: We demonstrate a new patterning technique for gallium-based liquid metals on flat substrates, which can provide both high pattern resolution (∼20 μm) and alignment precision as required for highly integrated circuits. In a very similar manner as in the patterning of solid metal films by photolithography and lift-off processes, the liquid metal layer painted over the whole substrate area can be selectively removed by dissolving the underlying photoresist layer, leaving behind robust liquid patterns as defined by the photolithography. This quick and simple method makes it possible to integrate fine-scale interconnects with preformed devices precisely, which is indispensable for realizing monolithically integrated stretchable circuits. As a way for constructing stretchable integrated circuits, we propose a hybrid configuration composed of rigid device regions and liquid interconnects, which is constructed on a rigid substrate first but highly stretchable after being transferred onto an elastomeric substrate. This new method can be useful in various applications requiring both high-resolution and precisely aligned patterning of gallium-based liquid metals.
authors.affiliation: Wearable Device Research Section, Electronics and Telecommunications Research Institute (ETRI) , 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.|Department of Advanced Device Technology, Korea University of Science and Technology (UST) , 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
authors.forename: Chan Woo
authors.initials: CW
authors.lastname: Park
authors.affiliation: Wearable Device Research Section, Electronics and Telecommunications Research Institute (ETRI) , 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.|Department of Advanced Device Technology, Korea University of Science and Technology (UST) , 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
authors.forename: Yu Gyeong
authors.initials: YG
authors.lastname: Moon
authors.affiliation: Department of Chemical and Biomolecular Engineering & Graphene Research Center KI for Nanocentury, Korea Advanced Institute of Science and Technology (KAIST) , 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Hyejeong
authors.initials: H
authors.lastname: Seong
authors.affiliation: Wearable Device Research Section, Electronics and Telecommunications Research Institute (ETRI) , 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.
authors.forename: Soon Won
authors.initials: SW
authors.lastname: Jung
authors.affiliation: Wearable Device Research Section, Electronics and Telecommunications Research Institute (ETRI) , 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Oh
authors.affiliation: Wearable Device Research Section, Electronics and Telecommunications Research Institute (ETRI) , 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.
authors.forename: Bock Soon
authors.initials: BS
authors.lastname: Na
authors.affiliation: Wearable Device Research Section, Electronics and Telecommunications Research Institute (ETRI) , 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.|Department of Advanced Device Technology, Korea University of Science and Technology (UST) , 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
authors.forename: Nae-Man
authors.initials: NM
authors.lastname: Park
authors.affiliation: Wearable Device Research Section, Electronics and Telecommunications Research Institute (ETRI) , 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.
authors.forename: Sang Seok
authors.initials: SS
authors.lastname: Lee
authors.affiliation: Department of Chemical and Biomolecular Engineering & Graphene Research Center KI for Nanocentury, Korea Advanced Institute of Science and Technology (KAIST) , 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Sung Gap
authors.initials: SG
authors.lastname: Im
authors.affiliation: Wearable Device Research Section, Electronics and Telecommunications Research Institute (ETRI) , 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.
authors.forename: Jae Bon
authors.initials: JB
authors.lastname: Koo
keywords: eutectic gallium−indium; lift-off patterning; liquid metal; monolithic integration; stretchable circuit