Integrated electronic and microfluidic packaging for CMOS biosensor chip

In recent years, advanced incorporation of complementary metal oxide semiconductor (CMOS) biosensor chips with sensory microarrays has gained tremendous attention. In this paper, we investigated a maskless approach to microfluidic channel fabrication that integrates seamlessly with CMOS biosensor chip packaging. The microfluidic channels were formed via precisely controlled dispensing of adhesive to define microfluidic dam structures. This was followed by encapsulation of the microfluidic dam with a lid, thereby producing an impervious seal. Four types of commercial adhesives used in medical/implantable devices were evaluated in this study; a silicone-based adhesive, an ultraviolet curable epoxy, an ultraviolet curing acrylate adhesive, and a thermal curing epoxy. The adhesives were evaluated based on the performance criteria such as: (i) critical dimension (CD) of microfluidic channels, (ii) minimum microfluidic dam height, (iii) biocompatibility, and (iv) bond strength of the adhesive between CMOS substrate film to the lid material. The test vehicles comprising of ITO glass lid material, SiN substrate material and various evaluated adhesives, were subjected to burst pressure leak test. From the results obtained, Dow Corning® 3140 silicone-based adhesive has the best performance as a suitable adhesive for microfluidic dam structure formation. Lastly, a seamless approach to integrating electronic and microfluidic packaging through the use of controlled adhesive dispensing and a pick and place assembly tool was demonstrated with the use of Dow Corning® 3140 adhesive for microfluidic biological applications.