Mechanical behavior of PDMS at low pressure

J. Bunyan, S. Tawfick

Research output: Contribution to journalArticlepeer-review


Polydimethylsiloxanes (PDMS) are used in a wide range of soft devices including lab-on-chip, soft robots and flexible electronics. These technologies are currently considered for space exploration applications. We experimentally study the effects of vacuum pressure on the dynamics of PDMS resonator and demonstrate that, unlike hard materials, it exhibits an appreciable change in modulus manifested as a shift in resonance frequency with varying pressure. To reveal this dependence, we carefully probe the dissipation due to air pressure damping acting on the surface of the membrane. For a 1 μm thick membrane, the modulus of the PDMS decreases when the pressure is below Pt = 3.175 Torr, whereas at pressures above Pt the dynamics are dominated by gas damping in the free molecular flow and viscous regimes. We conjecture that the observed effect is a consequence of a change in shear modulus resulting in a logarithmic linear relationship between pressure and stiffness for a circular PDMS membrane. These results are important for the application of PDMS microdevices at low pressure.

Original languageEnglish (US)
Article number075306
JournalMaterials Research Express
Issue number7
StatePublished - Jul 2017


  • Elastic modulus
  • Neo-Hookean solid
  • Polydimethylsiloxane PDMS
  • Pressure
  • Soft materials
  • Vacuum

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Metals and Alloys


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