Highly sensitive skin-mountable strain gauges based entirely on elastomers

Nanshu Lu, Chi Lu, Shixuan Yang, John Rogers*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

466 Scopus citations

Abstract

Quantifying naturally occurring strains in soft materials, such as those of the human body, requires strain gauges with equal or greater mechanical compliance. This manuscript reports materials and mechanics approaches are reported for an all-elastomer strain measurement device with gauge factor as high as 29 and with Young's modulus that approaches that of the human epidermis. These systems use thin carbon-black-doped poly(dimethylsiloxane) (CB-PDMS) for the strain gauges due to its high resistivity and strong dependence on strain, and thick carbon-nanotube-doped PDMS (CNT-PDMS) for the interconnects due to its comparatively low resistivity and weak dependence on strain. Devices composed of molded, straight resistors of CB-PDMS joined by serpentine-shaped interconnects of CNT-PDMS, both in a matrix substrate of PDMS, have electrical responses that depend almost entirely on the strain in the CB-PDMS. Integrated structures of this type have Young's moduli of 244 kPa, which lies within the range of values for the human epidermis. Such sheets can be readily laminated on and form conformal contact to the human skin, with only modest mechanical constraints on natural motions. Strains measured in this mode on the wrist are between 11.2% and 22.6%. Materials and mechanics approaches are reported for an all-elastomer strain measurement device with a gauge factor as high as 29 and Young's modulus that approaches that of the human epidermis. Measurements using a system of this type laminated on the human wrist reveal that strains in the skin induced by bending of the wrist are between 11.2% and 22.6%.

Original languageEnglish (US)
Pages (from-to)4044-4050
Number of pages7
JournalAdvanced Functional Materials
Volume22
Issue number19
DOIs
StatePublished - Oct 10 2012

Keywords

  • electrically conductive rubber
  • gauge factors
  • skin
  • strain gauges
  • stretchable materials

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Condensed Matter Physics
  • Electrochemistry

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