A novel microfluidic integration technology for PCB-based devices: Application to microflow sensing

Flow rate determination in microfluidic devices is important in numerous fields. In this paper, a novel technology which allows the formation of polymer microchannels on top of a specific PCB-based thermal flow senor is presented. The microchannel walls are defined by SU-8 on top of an array of Pt sensing elements. The sealing of the microchannel is performed by the thermal bonding of a PMMA plate (Plexiglas^(R)) on the upper surface of SU-8 layer which is covered with a thin PMMA layer. The width and depth of the microchannel can be fully controlled over an extended range. Excellent thermal isolation of the sensing elements is achieved due to the low thermal conductivity of the materials that comprise the structure. The conducted water flow rate measurements revealed high sensitivity and extended measurement range of the fabricated sensor.