Full-wafer in-situ fabrication and packaging of microfluidic flow cytometer with photo-patternable adhesive polymers

Abstract

Integration of microelectronics with microfluidics enables sophisticated lab-on-a-chip devices for sensing and actuation. In this paper, we investigate a novel method for in-situ microfluidics fabrication and packaging on wafer level. Two novel photo-patternable adhesive polymers were tested and compared, PA-S500H and DXL-009. The microfluidics fabrication method employs photo lithographical patterning of spin coated polymer films of PA or DXL and direct bonding of formed microfluidics to a top glass cover using die-to-wafer level bonding. These new adhesive materials remove the need for additional gluing layers. With this approach, we fabricated disposable microfluidic flow cytometers and evaluated the performance of those materials in the context of this application. DXL-009 exhibits lower autofluorescence compared to PA-S500H which improves detection sensitivity of fluorescently stained cells. Results obtained from the cytotoxicity test reveals that both materials are biocompatible. The functionality of these materials was demonstrated by detection of immunostained monocytes in microfluidic flow cytometers. The flexible, fully CMOS compatible fabrication process of these photo-patternable adhesive materials will simplify prototyping and mass manufacturing of sophisticated microfluidic devices with integrated microelectronics.

Investigation of packaging adhesive properties by molecular dynamics and experiments

“…MEMS (Micro-Electro-Mechanical Systems) packaging, developing on the basis of microelectronic packaging, utilizes an adhesive polymer as an intermediate layer to bond a die on substrate or shell. [1][2][3] Apart from the function of mounting die, the polymer layer also provides the capability of isolating the die from thermal stress induced by temperature change. [4] Therefore, the packaging quality heavily depends on the polymer property, such as Glass transition temperature (T g ), Young's modulus and shear modulus, because these parameters have a great influence on the residual stress level and long-term stability of packaged devices.…”