Wireless, soft electronics for rapid, multisensor measurements of hydration levels in healthy and diseased skin

Kyeongha Kwon, Heling Wang, Jaeman Lim, Keum San Chun, Hokyung Jang, Injae Yoo, Derek Wu, Alyssa Jie Chen, Carol Ge Gu, Lindsay Lipschultz, Jong Uk Kim, Jihye Kim, Hyoyoung Jeong, Haiwen Luan, Yoonseok Park, Chun Ju Su, Yui Ishida, Surabhi R. Madhvapathy, Akihiko Ikoma, Jean Won KwakDa Som Yang, Anthony Banks, Shuai Xu, Yonggang Huang, Jan Kai Chang*, John A. Rogers*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Precise, quantitative measurements of the hydration status of skin can yield important insights into dermatological health and skin structure and function, with additional relevance to essential processes of thermoregulation and other features of basic physiology. Existing tools for determining skin water content exploit surrogate electrical assessments performed with bulky, rigid, and expensive instruments that are difficult to use in a repeatable manner. Recent alternatives exploit thermal measurements using soft wireless devices that adhere gently and noninvasively to the surface of the skin, but with limited operating range (∼1 cm) and high sensitivity to subtle environmental fluctuations. This paper introduces a set of ideas and technologies that overcome these drawbacks to enable high-speed, robust, long-range automated measurements of thermal transport properties via a miniaturized, multisensor module controlled by a long-range (∼10 m) Bluetooth Low Energy system on a chip, with a graphical user interface to standard smartphones. Soft contact to the surface of the skin, with almost zero user burden, yields recordings that can be quantitatively connected to hydration levels of both the epidermis and dermis, using computational modeling techniques, with high levels of repeatability and insensitivity to ambient fluctuations in temperature. Systematic studies of polymers in layered configurations similar to those of human skin, of porcine skin with known levels of hydration, and of human subjects with benchmarks against clinical devices validate the measurement approach and associated sensor hardware. The results support capabilities in characterizing skin barrier function, assessing severity of skin diseases, and evaluating cosmetic and medication efficacy, for use in the clinic or in the home.

Original languageEnglish (US)
Article numbere2020398118
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number5
StatePublished - Feb 2 2021


  • Biomedical devices
  • Diagnostics
  • Flexible electronics
  • Health monitoring
  • Wireless electronics

ASJC Scopus subject areas

  • General


Dive into the research topics of 'Wireless, soft electronics for rapid, multisensor measurements of hydration levels in healthy and diseased skin'. Together they form a unique fingerprint.

Cite this