title: Thin, Soft, Skin-Mounted Microfluidic Networks with Capillary Bursting Valves for Chrono-Sampling of Sweat.
abstract: Systems for time sequential capture of microliter volumes of sweat released from targeted regions of the skin offer the potential to enable analysis of temporal variations in electrolyte balance and biomarker concentration throughout a period of interest. Current methods that rely on absorbent pads taped to the skin do not offer the ease of use in sweat capture needed for quantitative tracking; emerging classes of electronic wearable sweat analysis systems do not directly manage sweat-induced fluid flows for sample isolation. Here, a thin, soft, "skin-like" microfluidic platform is introduced that bonds to the skin to allow for collection and storage of sweat in an interconnected set of microreservoirs. Pressure induced by the sweat glands drives flow through a network of microchannels that incorporates capillary bursting valves designed to open at different pressures, for the purpose of passively guiding sweat through the system in sequential fashion. A representative device recovers 1.8 µL volumes of sweat each from 0.8 min of sweating into a set of separate microreservoirs, collected from 0.03 cm2area of skin with approximately five glands, corresponding to a sweat rate of 0.60 µL min-1per gland. Human studies demonstrate applications in the accurate chemical analysis of lactate, sodium, and potassium concentrations and their temporal variations.
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA.
authors.forename: Jungil
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Mechanical Engineering, Ajou University, San 5, Woncheon-Dong, Yeongtong-Gu, Suwon, 16499, South Korea.
authors.forename: Daeshik
authors.initials: D
authors.lastname: Kang
authors.affiliation: Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
authors.forename: Seungyong
authors.initials: S
authors.lastname: Han
authors.affiliation: Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
authors.forename: Sung Bong
authors.initials: SB
authors.lastname: Kim
authors.affiliation: Center for Bio-Integrated Electronics, Departments of Materials Science and Engineering, Biomedical Engineering, Chemistry, Mechanical Engineering, Electrical Engineering and Computer Science, and Neurological Surgery, Simpson Querrey Institute for Nano/Biotechnology, McCormick School of Engineering and Feinberg School of Medicine, Northwestern University, Evanston, IL, 60208, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Rogers
mesh_terms: D006801:Humans; D056656:Lab-On-A-Chip Devices; D019344:Lactic Acid / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D012867:Skin / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013542:Sweat / Q000378:metabolism*; D014882:Water-Electrolyte Balance
chemical_list: D019344:Lactic Acid; D012964:Sodium; D011188:Potassium
keywords: capillary bursting valve; epidermal; microfluidics; sequential capture; sweat