Integrated Void Fraction Sensors for Two-phase, Microfluidic Systems

AbstractThe design, fabrication and integration of capacitive void fraction sensors for microfluidic applications in silicon microchannels of 100μm wide and 500μm deep are described. Microfabrication steps such as electrode deposition, glass dicing and drilling and the anodic bonding process are elucidated. A read-out circuit was designed to convert capacitive input signals into a large-swing analog output signal. The signal processing algorithm is discussed. Measurements showing the variation of the output signal in function of the gas content in the air/water-mixture that was pumped through the microchannels are presented