A series of sinusoidal wavy microchannels with different phase shifts and wavelengths were fabricated on the silicon wafer based on the MEMS technology.Flow frictions in these sinusoidal wavy microchannels were investigated experimentally.Results show that the flow friction in wavy microchannels is higher compared with the smooth straight microchannels with the same hydraulic diameter.Both the phase shift and the wavelength have effect on the flow friction in wavy microchannels.For the microchannels with the same wavelength

the flow friction increases as the phase shift increases.However

the influence of wavelength is complicated.For the microchannels with phase shift of 0

the flow friction normally increases as the wavelength decreases with the exception for the microchannel with the smallest wavelength.For the microchannels with phase shift of π

the flow friction decreases as the wavelength decreases due to the decrease of the throat size in the microchannels.The investigation also shows that as the wavelength decreases

the influence of phase shift on the flow friction decreases.For the wavelength of 0.5 mm

there is little difference in the flow friction between the microchannels with 0 and π phase shifts.