Abstract
This paper presents the validation of molecule-based pressure sensors in straight PDMS microchannel and further applications on acquiring the detailed pressure profiles in constricted PDMS microchannel. The experimental technique using molecule-based pressure sensor has been applied in various microscale measurements; however, deviations between theoretical and experimental results were also reported. The inconsistency is most likely due to the rough and heterogeneous channel surfaces. To validate the experimental technique with classic straight microchannel flow, the pressure distributions were measured at Reynolds numbers ranging from 10 to 86, and Knudsen numbers ranging from 0.0015 to 0.014. The experimental results acquired in the straight microchannel show excellent agreements with analytical solutions obtained from NavierStokes equations and first-order slip boundary condition. The pressure profiles acquired in the constricted microchannel show an apparent pressure drop, which indicates the flow recirculation, near the constriction area. The pressure recovery after the constriction structure was delayed further with increasing flow rate. There were more than 3000 data points acquired inside the 1cm long PDMS microchannel from the entrance to the exit and 33 data points were acquired across the microchannel width 100m. Detailed resolution up to 3m per pixel in the local pressure evolution has been realized in the current experimental setup using a standard camera lens and extension tubes. © 2012 IOP Publishing Ltd.