Microchannels for applications in liquid dosing and flow-rate measurement (original) (raw)

To investigate the performance of microengineered fluid channels in liquid dosing applications, llow-rate mc,'tsurements have been l)erliwmed with various channel geometries in a range from 0.0l to 1000 ixl min-~. An optical flow-measurement technique has been developed to enhance the measurement range into the desired low flow range ( 10-3 to I ~1 rain-t), and is compared to a standard gravimetric method, which is preferably used for flow rates above 1 ~1 min-~. In addition, influences of the temperttture-dependent viscosity and effects arising from fluidmechanical characteristics are studied. These influences are also calculated from laminar llow theory and semi-empMcal models to obtain a theoretical model. It is found that the theoretical model is able to describe the measurement results well in the whole flow 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 flow. In a temperature range from 20 to 50°C excellent agreement is l'ound. © 1997 Elsevier Science S.A.