Along with the rapid growth of research of microfluidics, monitoring and understanding micro flow behavior is a challenge for researchers. Particle Image Velocimetry (PIV), a powerful tool that makes flow visible, was extended to microscale by Santiago et al. 1998. In this paper, we presented the micro Particle Image Velocimetry (PIV) system at Nanyang Technological University (NTU), its calibration and characterizations of microfluidic devices using PIV. Since the fully developed microchannel flow has been well investigated, it is suitable to calibrate the measurements of PIV. In our experiment, an in-channel microdispenser fabricated on printed circuit board is used to form a microchannel. A syringe pump forces water that contains fluorescent particles. The flow field is obtained by PIV. At the same time, a three-dimensional model with ANSYS/FLOTRAN was used. The comparison between the two results demonstrates that our PIV system works well. Furthermore we use this system to characterize a Tesla valve - a non-moving part valve. The valve consists of a fluid channel structure that has rectification property, which favors forward flow while hampers reverse flow. The velocity fields are also validated by ANSYS/FLOTRAN. 顯微粒子成像測速系統(tǒng)(Micro PIV)