title: Ultraflexible, large-area, physiological temperature sensors for multipoint measurements.
abstract: We report a fabrication method for flexible and printable thermal sensors based on composites of semicrystalline acrylate polymers and graphite with a high sensitivity of 20 mK and a high-speed response time of less than 100 ms. These devices exhibit large resistance changes near body temperature under physiological conditions with high repeatability (1,800 times). Device performance is largely unaffected by bending to radii below 700 µm, which allows for conformal application to the surface of living tissue. The sensing temperature can be tuned between 25 °C and 50 °C, which covers all relevant physiological temperatures. Furthermore, we demonstrate flexible active-matrix thermal sensors which can resolve spatial temperature gradients over a large area. With this flexible ultrasensitive temperature sensor we succeeded in the in vivo measurement of cyclic temperatures changes of 0.1 °C in a rat lung during breathing, without interference from constant tissue motion. This result conclusively shows that the lung of a warm-blooded animal maintains surprising temperature stability despite the large difference between core temperature and inhaled air temperature.
authors.affiliation: Electrical and Electronic Engineering and Information Systems, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan; Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Bunkyo-ku, Tokyo 113-8656, Japan; yokota@ntech.t.u-tokyo.ac.jp someya@ee.t.u-tokyo.ac.jp.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yokota
authors.affiliation: Electrical and Electronic Engineering and Information Systems, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan; Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Bunkyo-ku, Tokyo 113-8656, Japan;
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Electrical and Electronic Engineering and Information Systems, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan;
authors.forename: Yuki
authors.initials: Y
authors.lastname: Terakawa
authors.affiliation: Electrical and Electronic Engineering and Information Systems, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan; Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX 75080-3021;
authors.forename: Jonathan
authors.initials: J
authors.lastname: Reeder
authors.affiliation: Electrical and Electronic Engineering and Information Systems, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan; Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Bunkyo-ku, Tokyo 113-8656, Japan;
authors.forename: Martin
authors.initials: M
authors.lastname: Kaltenbrunner
authors.affiliation: Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080-3021;
authors.forename: Taylor
authors.initials: T
authors.lastname: Ware
authors.affiliation: Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75080-3021;
authors.forename: Kejia
authors.initials: K
authors.lastname: Yang
authors.affiliation: Information Science and Technology, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan;
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Mabuchi
authors.affiliation: Department of Cardiothoracic Surgery, The University of Tokyo Hospital, Bunkyo-ku, Tokyo 113-8655, Japan;
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Murakawa
authors.affiliation: Electrical and Electronic Engineering and Information Systems, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan; Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Bunkyo-ku, Tokyo 113-8656, Japan;
authors.forename: Masaki
authors.initials: M
authors.lastname: Sekino
authors.affiliation: Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX 75080-3021;
authors.forename: Walter
authors.initials: W
authors.lastname: Voit
authors.affiliation: Electrical and Electronic Engineering and Information Systems, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan; Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Bunkyo-ku, Tokyo 113-8656, Japan; The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sekitani
authors.affiliation: Electrical and Electronic Engineering and Information Systems, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan; Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Bunkyo-ku, Tokyo 113-8656, Japan; yokota@ntech.t.u-tokyo.ac.jp someya@ee.t.u-tokyo.ac.jp.
authors.forename: Takao
authors.initials: T
authors.lastname: Someya
mesh_terms: D000818:Animals; D001831:Body Temperature; D006108:Graphite / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D051381:Rats; D014961:X-Ray Diffraction
chemical_list: D011108:Polymers; D006108:Graphite
keywords: biomedical devices; flexible electronics; organic electronics; temperature sensor