Polydimethylsiloxane (PDMS) is a flexible polymer featured with good resilience, high chemical resistance and transmission. It can be used as a flexible composite for various sensors due to its ability to respond readily to tensile, torsion, and compression. 

In many cases, flexible film is required to adapt the curved surface and perform larger camber deformation, such as the joint sensor and the flexible imprinting on the non-planar surfaces.  

The mechanical properties of PDMS film that matter most are relationship between input force and curvature of deformation, and the maximum received curvature that can be achieved before fracture.  

Researchers from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences studied the camber deformation of the PDMS film, as well as the relationship between the deformation characteristics and maximum received curvature and the properties of PDMS films. The study was published in Optical Materials. 

The researchers fabricated PDMS films with different composition ratio of curing agent and film thickness, and measured the Young's modulus of each film according to the Hooke’s law.

Then, they set up a vacuum chamber to observe the camber deformation and the fracture at the maximum received curvature. The distribution of deformation and shear elastic strain of the PDMS film was calculated by finite element simulation.  

The research results indicated that deformation was depended on the pressure, Young's modulus and film thickness; the maximum received curvature was mainly affected by the film thickness, and the fracture shear strain was about 27~32% (mm^-1) of film thickness. 

The study provides fundamental insights into the mechanical properties and practical instructions for PDMS flexible films.

Photo of the flexible film (Image by SIAT) 

Camber deformation and fracture process of the PDMS film (M10) (Image by SIAT)