Absorption of Small Hydrophobic Molecules in PDMS

Introduction

While PDMS is an outstanding material for rapid prototyping of microfluidic devices, mass production of PDMS chips is problematic due to the low speed of casting and curing processes. Slow cycle times can be partially overcome using liquid silicone rubber injection molding; however, industrial acceptance of PDMS microfluidic devices for drug development and other applications is still hindered by the strong propensity of PDMS to absorb small hydrophobic molecules such as fluorescent dyes and drugs.

In rapid prototyping of microfluidic devices, an alternative approach is to use other optically clear castable polymers such as polyurethanes that resist absorption of small hydrophobic molecules and can be processed similarly as PDMS. [pdf]

However, the process of casting elastomeric polyurethane microfluidic devices has been specifically developed for prototyping in a laboratory setting. For commercial mass production of flexible microfluidic devices, it is more advantageous to use optically clear thermoplastic elastomers such as styrenic block copolymers based on styrene-ethylene-butylene-styrene (SEBS) that are amenable to high-throughput injection molding and extrusion. [pdf]