title: Epidermal impedance sensing sheets for precision hydration assessment and spatial mapping.
abstract: This paper presents a class of hydration monitor that uses ultrathin, stretchable sheets with arrays of embedded impedance sensors for precise measurement and spatially multiplexed mapping. The devices contain miniaturized capacitive electrodes arranged in a matrix format, capable of integration with skin in a conformal, intimate manner due to the overall skin-like physical properties. These "epidermal" systems noninvasively quantify regional variations in skin hydration, at uniform or variable skin depths. Experimental results demonstrate that the devices possess excellent uniformity, with favorable precision and accuracy. Theoretical models capture the underlying physics of the measurement and enable quantitative interpretation of the experimental results. These devices are appealing for applications ranging from skin care and dermatology, to cosmetology and health/wellness monitoring, with the additional potential for combined use with other classes of sensors for comprehensive, quantitative physiological assessment via the skin.
authors.forename: Xian
authors.initials: X
authors.lastname: Huang
authors.forename: Huanyu
authors.initials: H
authors.lastname: Cheng
authors.forename: Kaile
authors.initials: K
authors.lastname: Chen
authors.forename: Yilin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yihui
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yuhao
authors.initials: Y
authors.lastname: Liu
authors.forename: Chenqi
authors.initials: C
authors.lastname: Zhu
authors.forename: Shao-Chi
authors.initials: SC
authors.lastname: Ouyang
authors.forename: Gil-Woo
authors.initials: GW
authors.lastname: Kong
authors.forename: Cunjiang
authors.initials: C
authors.lastname: Yu
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Huang
authors.forename: John A
authors.initials: JA
authors.lastname: Rogers
mesh_terms: D001834:Body Water / Q000378:metabolism*; D003217:Conductometry / Q000295:instrumentation*; D017097:Electric Impedance; D004566:Electrodes; D004817:Epidermis / Q000378:metabolism*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D008567:Membranes, Artificial; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012869:Skin Absorption / Q000502:physiology*; D062211:Spatio-Temporal Analysis
chemical_list: D008567:Membranes, Artificial