A system for micro/nano fluidic flow diagnostics

A system for flow measurement in micro/nano fluidic components is presented. Microfabricated arrays of straight channels with noncircular cross-sections were used for flow rate measurement. The calculated flow rates in these channels were determined using a finite difference approximation method. A pneumatic pumping system was utilized to control the pressure drop across the channels and flow rates were measured by collecting the fluids on a sensitive balance. The experimental setup was validated using long narrow circular tubes that mimic the range of flow resistances characteristic of micro/nano fluidic devices. Two types of channels cross-section were investigated. The first type contained an array of channels that were approximately trapezoidal (microchannels, approximately 6.5 microm deep) in cross-section and exhibited flow rates of 27.7--119.4 micro L/min within a pressure range of 64.1--277.1 kPa (9.3--40.2 psi). The second type contained an array of channels that were approximately arc-shaped (nanochannels, approximately 600 nm deep) and generated flow rates of 0.29--0.99 micro L/min within a pressure range of 137.2--334.4 kPa (19.9--48.5 psi). The flow rates calculated by the finite difference approximation method were within 5.5% and 19.68% of the average experimental flow rates in the microchannels and nanochannels, respectively.