The precise deterkimnation of flow rates is an essential prescondition for the application of micro fluid devices in clinical diagnostics, in quantiative product measurement in miniaturised combinatorial chemistry, and in miniaturished high throughput screening. Based on the well established thermal measurement principle, a sensor concept has been realised, which combines very low transport rates in micro channels with the extremely low parastic heat capacity o f a free-standing thin film transducer. This way, flow rates in the nl/min region can be measured precisely. The sensor is a 3-chip moduel. It can easily be concected with other mocro fluid modules as reactors, pumpos and chemical sensors, and is, therefore, well suited for freely configurable micro fluid arrangements. It detects the motion of a liquid column caused by the release of single droplets (500 pl) from a si chip pump in the closed chanel.
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