Solid-state ISFET flow meter fabricated with a planar packaging process for integrating microfluidic channel with CMOS IC chip

This study presents a solid-state ISFET flow meter fabricated with an innovative planar packaging process. It is challenge to integrate a CMOS chip with the microfluidic channel since the physical dimension of the CMOS chip may cause the leakage during packaging the IC chip with microfluidic channels. This study develops a planar packaging process which uses PDMS as the adhesive to embed the IC chip in a cavity over the PCB. Result shows that the interfacial step between the IC chip and the surrounding PDMS substrate is less than 5 μm such that microfluidic channel can be sealed free of leakage with the developed planar package process. The sealed ISFET chip is used for measuring the flow rate of non-ionic solutions including acetone, ethanol and glycerol of slow flow rate. Results show that the flow rate measurement exhibited good reproducibility in the flow rate ranging from 66 to 1700 μm/s. Moreover, the whole packaging process can be achieved in 40 min The developed method provides a simple yet efficient method to integrate CMOS IC chip with microfluidic systems.