A microfluidic system with embedded acoustic wave sensor for in situ detection of dynamic fluidic properties

A microfluidic system with acoustic wave sensor employing quartz crystal microbalance embedded in the microfluidic channel was developed by soft-lithography technique and characterized by measuring resonance frequency of the sensor under different service conditions. Detections of dynamic fluids in various concentrations and flow rates showed that shift of resonant frequency was observed when there was variation in mass or viscosity of the fluid passing through the microchannels. Through a calibration experiment by monitoring continuous flowing fluids with suspended microparticles, the sensitivity of the system was found to be ∼15 Hz cm2/ng. All these results suggest that the microfluidic system can be employed in in situ monitoring of chemical and biochemical processes involving mass and/or viscosity changes within the microfluidic system.