A positive pressure-driven PDMS pump for fluid handling in microfluidic chips

By utilizing the high gas permeability of polydimethylsiloxane (PDMS), a simple positive pressure-driven pumping method was introduced. The pump was an aerated PDMS with a central channel in it and packing with a transfusion bottle. It could be attached to the inlet of microfluidic chip using a Teflon tube to release the air into the microfluidic system and then to create a positive pressure for driving fluid. In comparison with the degas-based PDMS pump, positive pressure-driven PDMS pump offered increased system flexibility and reduced individual device fabrication complexity due to its independence and versatility. More importantly, it offered the advantages that the PDMS pump could be wrapped in transfusion bottles to meet the readily available requirements, and it also easily assembled, which only required the user use a Teflon tube to connect a PDMS pump and a microfluidic chip. This assembly provided great freedom to meet different pumping requirements. Furthermore, this PDMS pump could offer many possible configures of pumping power by adjusting the geometries of the pump or by combining different pump modules, the adjustment of pumping capacity was investigated. To help design pumps with a suitable pumping performance, the sealing effect, pumping pressure and flow rate were also investigated. The results indicated that the performance of the positive pressure-driven PDMS pump was reliable. Finally, we demonstrated the utility of this pumping method by applying it to a PDMS-based viscometer microfluidic chip.