Assembly and simple demonstration of a micropump installing PDMS-based thin membranes as flexible micro check valves.

Integration of chemical or biochemical systems creates extremely efficient devices exploiting the advantages of microspaces. Recently, various microfluidic devices have been developed to make micro chemical processes more sophisticated. On the other hand, we demonstrated the concept of a cardiomyocyte pump using only chemical energy input to cells as a driver (Tanaka et al. Lab Chip 6(3), pp. 362-368). However, its flow rate was too poor to be applied for practical applications of micro chemical systems mainly because of the inefficiency of the check valves made of polyimide. As cardiomyocytes' force is weak, more flexible materials must be used. In this report, a more flexible material, poly(dimethylsiloxane) (PDMS) check valves were designed and fabricated, and then, the check valve function was demonstrated by pumping fluid in an assembled micropump incorporating the PDMS check valves. Water was dropped on an inlet of the microchannel, and a diaphragm of the micropump was oscillated using a pair of tweezers to prove the function of the valves. From the result, pumping volume per stroke was calculated as 1.7 micro/stroke. The developed valves are not only usable for our cardiomyocyte pumps but also applicable to general micro and nano fluidic devices for biomedical fields such as immune assay systems owning to easy and inexpensive fabrication method of the valves.