A new method for polydimethylsiloxane (PDMS) microfluidic chips to maintain vacuum-driven power using Parylene C

A novel method for making Parylene C-coated PDMS microfluidic chips is presented for the first time here. This method can maintain the vacuum-driven power of PDMS microfluidic chips for more than 30   days. Parylene C membrane has quite low permeability to water vapor and gases such as nitrogen and oxygen. In addition, Parylene C membrane is transparent and has chemical inertness. Thus, the detection of reaction results on the chip would not be affected. The investigated results showed that a thicker Parylene C membrane and a thicker PDMS microfluidic chip resulted in a longer vacuum holding time. Digital polymerase chain reaction (dPCR) analyses were used to verify that the new method would not influence the biochemical analyses in these microfluidic chips. Furthermore, the evacuation process and Parylene C coating process can be carried out at the same time, and the operation is quite easy. This new method prolongs greatly the storage lives of vacuum-driven PDMS microfluidic chips, and will make them become widely accepted in point-of-care diagnostics.