Microchannels for applications in liquid dosing and flow-rate measurement

To investigate the performance of microengineered fluid channels in liquid dosing applications, Bow-rate measurements have been performed with various channel geometries in a range from 0.01 to 1000 mu l min(-1). An optical flow-measurement technique has been developed to enhance the measurement range into the desired low Bow range (10(-3) to I mu l min(-1)), and is compared to a standard gravimetric method, which is preferably used for flow rates above 1 mu l min(-1). In addition, influences of the temperature-dependent viscosity and effects arising from fluidmechanical characteristics are studied. These influences are also calculated from laminar Row theory and semi-empirical models to obtain a theoretical model. It is found that the theoretical model is able to describe the measurement results well in the whole Row range. The model is implemented on a PC-based system, which measures the pressure drop across the microchannel and the fluid temperature and calculates the Row. In a temperature range from 20 to 50 degrees C excellent agreement is found. (C) 1997 Elsevier Science S.A.