PDMS is an elastomer which holds many appealing properties for use in microfabricated systems. It has been widely used in research since its first published use by George Whiteside’s group in 1997^[1]. Since then, ease of fabrication and relatively low costs have made PDMS a staple of microfluidic research.

The PDMS fabrication process involves mixing elastomer and curing agent, which is then cast on a mold. This mold is typically either cured PDMS, polymer, or (most commonly) a wafer prepared using photolithography. While this process offers much for research and prototyping purposes, low throughput and difficulty of scale-up mean that development of mass produced PDMS parts is unfeasible.

Therefore, the majority of commercial microfluidics parts are manufactured from rigid Thermoplastic. Many parts, however, must be transitioned from their original PDMS prototypes to thermoplastic during commercial development. Here, we present some necessary considerations for this process.

Thermoplastics

A range of thermoplastics are used in microfluidics and each has different properties which are desirable for different applications. The most regularly used are polycarbonate (PC), polystyrene (PS), poly(methyl methacrylate) (PMMA), polyvinyl chloride (PVC), polyimide (PI), and the group of Cyclic Olefin polymers (CO polymers) which includes cyclic olefin copolymer (COC), cyclic olefin polymer (COP), and cyclic block copolymer (CBC)^[2].

Mechanical Properties

PDMS is a flexible silicone which, when placed under pressure, will deform. Researchers have used this property to integrate pressure actuated valves into parts in order to control fluid flow. When transitioning from PDMS to thermoplastic, alternative flow control systems must be implemented and flow control elements must be in place to replicate the valves integrated into PDMS...Read More