Computational models for the determination of depth-dependent mechanical properties of skin with a soft, flexible measurement device

Jianghong Yuan; Canan Dagdeviren; Yan Shi; Yinji Ma; Xue Feng; John A Rogers; Yonggang Huang

doi:10.1098/rspa.2016.0225

Computational models for the determination of depth-dependent mechanical properties of skin with a soft, flexible measurement device

Proc Math Phys Eng Sci. 2016 Oct;472(2194):20160225. doi: 10.1098/rspa.2016.0225.

Authors

Jianghong Yuan¹, Canan Dagdeviren², Yan Shi³, Yinji Ma¹, Xue Feng³, John A Rogers⁴, Yonggang Huang⁵

Affiliations

¹ Center for Mechanics and Materials, Tsinghua University, Beijing 100084, People's Republic of China; AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, People's Republic of China; Department of Civil an Environmental Engineering, Northwestern University, Evanston, IL 60208, USA; Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA; Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA; Skin Disease Research Center, Northwestern University, Evanston, IL 60208, USA.
² The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Harvard Society of Fellows, Harvard University, Cambridge, MA 02138, USA.
³ Center for Mechanics and Materials, Tsinghua University, Beijing 100084, People's Republic of China; AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, People's Republic of China.
⁴ Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
⁵ Department of Civil an Environmental Engineering, Northwestern University, Evanston, IL 60208, USA; Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA; Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA; Skin Disease Research Center, Northwestern University, Evanston, IL 60208, USA.

Abstract

Conformal modulus sensors (CMS) incorporate PZT nanoribbons as mechanical actuators and sensors to achieve reversible conformal contact with the human skin for non-invasive, in vivo measurements of skin modulus. An analytic model presented in this paper yields expressions that connect the sensor output voltage to the Young moduli of the epidermis and dermis, the thickness of the epidermis, as well as the material and geometrical parameters of the CMS device itself and its encapsulation layer. Results from the model agree well with in vitro experiments on bilayer structures of poly(dimethylsiloxane). These results provide a means to determine the skin moduli (epidermis and dermis) and the thickness of the epidermis from in vivo measurements of human skin.

Keywords: conformal modulus sensors; electromechanical coupling; epidermis and dermis; skin moduli.

Grants and funding

R01 EB019337/EB/NIBIB NIH HHS/United States