title: Ultraflexible organic amplifier with biocompatible gel electrodes.
abstract: In vivo electronic monitoring systems are promising technology to obtain biosignals with high spatiotemporal resolution and sensitivity. Here we demonstrate the fabrication of a biocompatible highly conductive gel composite comprising multi-walled carbon nanotube-dispersed sheet with an aqueous hydrogel. This gel composite exhibits admittance of 100 mS cm(-2) and maintains high admittance even in a low-frequency range. On implantation into a living hypodermal tissue for 4 weeks, it showed a small foreign-body reaction compared with widely used metal electrodes. Capitalizing on the multi-functional gel composite, we fabricated an ultrathin and mechanically flexible organic active matrix amplifier on a 1.2-μm-thick polyethylene-naphthalate film to amplify (amplification factor: ∼200) weak biosignals. The composite was integrated to the amplifier to realize a direct lead epicardial electrocardiography that is easily spread over an uneven heart tissue.
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656, Japan.|The Institute of Scientific and Industrial Research, Osaka University, 8-1, Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sekitani
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Tomoyuki
authors.identifier: http://orcid.org/0000-0003-1546-8864
authors.initials: T
authors.lastname: Yokota
authors.affiliation: Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kuribara
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656, Japan.|Soft Matter Physics, Linz Institute of Technology LIT, Johannes Kepler University Linz, Altenbergerstrasse 69, Linz 4040, Austria.
authors.forename: Martin
authors.identifier: http://orcid.org/0000-0002-7247-9183
authors.initials: M
authors.lastname: Kaltenbrunner
authors.affiliation: Chemical Resource Laboratory, Tokyo Institute of Technology, 4259R1-1, Nagatsuda, Midoriku, Yokohama, Kanagawa 226-8503, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Fukushima
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Sekino
authors.affiliation: Department of Biomedical Engineering, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Isoyama
authors.affiliation: Department of Biomedical Engineering, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Abe
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656, Japan.|Photon Science Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Onodera
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656, Japan.|Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.|Photon Science Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Someya
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D020405:Dermis / Q000187:drug effects / Q000502:physiology; D004562:Electrocardiography / Q000295:instrumentation*; D004566:Electrodes; D004581:Electronics / Q000295:instrumentation* / Q000379:methods; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D005549:Foreign-Body Reaction / Q000517:prevention & control; D006041:Goats; D020100:Hydrogels / Q000737:chemistry* / Q000494:pharmacology; D008297:Male; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009281:Naphthalenes / Q000737:chemistry; D010496:Pericardium / Q000187:drug effects / Q000502:physiology; D018583:Pliability; D011095:Polyethylenes / Q000737:chemistry; D011817:Rabbits; D051381:Rats
chemical_list: D001672:Biocompatible Materials; D020100:Hydrogels; D037742:Nanotubes, Carbon; D009281:Naphthalenes; D011095:Polyethylenes