Characterization study of bonded and unbonded polydimethylsiloxane aimed for bio-micro-electromechanical systems-related applications

Authors have demonstrated that by controlling the mixing ratio of polydimethylsiloxane's (PDMS's) two components-base polymer (part A) and a curing agent (part B)-different mechanical properties of PDMS can be achieved. Test results show that the Young's modulus decreases as the increasing of mixing ratios (A: B). However, there is a transitional mixing ratio (part A:part B=10) after which the Young's modulus is almost independent of the mixing ratio. The PDMS's thickness plays an important role in determining the mechanical properties. The results show that the thinner the PDMS, the stiffer it behaves. The bonding strength between two cured PDMS parts with different mixing ratios shows that it depends on the mixing ratio. A maximum bonding strength of 130 kPa occurs on a bonded couple with mixing ratios of 30A: 1 B and 3A: 1 B, respectively. The fracture on bonded specimens does not occur at the bonding interfaces. Instead it occurs at the side with a larger portion of part A. The intermediate material property formed at the interface is attributed to the diffusion layer formed. (c) 2007 Society of Photo-Optical Instrumentation Engineers.