A microfabricated flow chamber for optical measurements in fluids

The fabrication and initial testing of silicon micromachined flow chambers for applications in flow cytometry are reported. The flow chambers consist of a hexagonal flow duct with inlet and outlet ports, thin-film windows on the top and bottom of the duct, and integrated optical waveguides positioned to intercept the center of the duct within the visible area defined by the windows. An opening for a hypodermic needle allows injection of a suspension of microscopic particles into a liquid stream flowing through the duct. Each component of the device was tested individually, and good agreement between the experimental data and theoretical models was observed. Laminar flow was observed in several prototypes up to mean flow speeds of 3 m/s. No leaks were detected for inlet pressures as high as 30 psi.<
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