Nonintrusive pressure measurement in microfluidic systems via backscattering interferometry

Measurement of pressure in microfluidic systems typically requires intrusion into the channel, rendering direct pressure and fluid flow rate measurements impractical outside of a laboratory environment. A nonintrusive measurement technique has been successfully developed to measure fluid pressure in both gas and liquids in microchannels. The technique, which consists of an unfocused laser beam impinging a microchannel to generate interferometric fringes, contains information on both channel wall deflection and changes in refractive index of the liquid or gas. The effects can be isolated through interpretation of fringe shift and changes in fringe morphology. Using finite element analysis to determine microchannel wall deflection in conjunction with refractive index data enables accurate quantification of pressures in microchannels. © 2014 Springer-Verlag Berlin Heidelberg