A microfluidic experimental platform with internal pressure measurements

Large inconsistencies in previous microchannel pressure drop data have motivated the development of a microchannel experimental platform that enables the measurement of pressures inside the microchannel. The system utilizes bulk etched silicon components that integrate pressure-sensing membranes with the microchannel test section. The deflection of the membranes is detected by an off-chip, optical-lever based system that allows the sensors to be calibrated for pressure measurement. The sensor sensitivity can be adjusted after microfabrication is complete, allowing for sensor optimization after fabrication. The sensor can be used in many applications where the fabrication of electrical contacts, piezoresistors and capacitors is problematic. Calibration uncertainties as low as 2% have been obtained during actual use of the system. The presented system resolves many of the issues associated with measuring pressures inside microchannels for the range of hydraulic diameters tested, 25–100 μm. The system has been used to study pressure drop in microchannels and a sample of the results is presented. It has been found that standard models with appropriate assumptions can accurately predict the measured pressure data.