Water-vapor permeability control of PDMS by the dispersion of collagen powder

Polydimethylsiloxane (PDMS) has been widely used as a material for micro-total analysis system (μTAS) devices due to the superior nature of its manufacturability and chemical resistance, etc. PDMS is known to allow the permeation of gas and water vapor. This characteristic was applied to ensure an efficient oxygen supply to cells cultivated in micro-chambers and power-free sample injection into micro-fluidic devices. Some applications, such as long-term experiments with aqueous samples, however, prefer to avert the permeation of water vapor through PDMS. This paper reports on a new method to control the water-vapor permeability of PDMS by dispersing collagen powder (collagen/PDMS polymer). First, we evaluated the manufacturability and material strength of the collagen/PDMS polymer to see whether the polymer could be employed as a material for μTAS devices. Subsequently, we designed and fabricated micro-fluidic devices to directly measure the amount of water vapor permeating through a PDMS or collagen/PDMS membrane, and evaluated the effect of the dispersed collagen. The use of the dispersed collagen powder successfully reduced the water-vapor permeability of PDMS by 54%.