Infrared thermal velocimetry for nonintrusive flow measurement in silicon microfluidic devices

Measurement of velocity is essential for verification of the performance of many microelectromechanical system (MEMS) based fluidic devices. MEMS devices are usually made of silicon which is transparent at infrared wavelengths. Infrared thermal velocimetry has been developed to measure the velocity in silicon microchannels utilizing the infrared transparency of silicon. Applications are broad and include MEMS fluidic devices and bio-fluidic elements. Briefly, an infrared laser heats the flowing fluid in a silicon microchannel and the recording of the thermal image of the moving heated liquid permits determination of the average flow velocity. It has been demonstrated that this method can be used to measure a wide range of velocities (1 cm/s-1 m/s or higher) with an accuracy of +/-10%. The velocity of the maximum radiative intensity point (V-MRIP) along the center of the channel is chosen to characterize the velocity in the channel. Numerical results show good agreement with the experimental results. (C) 2003 American Institute of Physics.