B3.3 - Fabrication of Microfluidic Devices Using SU-8 for Detection and Analysis of Viruses

Abstract

A passive microfluidic device using SU-8 photoresist has been developed for detection and analysis of viruses. Due to its high aspect ratio with almost vertical sidewalls and its chemical stability, SU-8 offers a wide variety of applications in the fabrication of microfluidic systems. This photoresist is transparent allowing optical detection and thus, identification of biomolecules. Additionally, SU-8 shows a good biocompatibility offering the possibility to develop assay on the surface that allows the specific binding of biomolecules for analytical applications. In this work, the performance of the microfluidic device has been successfully demonstrated by detection of specific contaminants in test solutions. The microfluidic chip is composed of SU-8 microstructures which have been fabricated by means of photolithography, using glass and silicon as substrate materials. Beside the fabrication of microchannels by means of SU8, we have also used SU-8 as adhesive layer. Introduction Microfluidic chips are nowadays a concept widely used in different fields like biology, pharmacy, medicine and other biotechnologies. Microfluidic or lab-on-a-chip technology promises significant advantages for carrying out rapid, efficient and specific analysis of microorganisms, which could be found in chemical substances. The cost and reagent consumption required for analysis will be reduced by using microfluidic devices due to their small size that is very useful for μTAS (Micro Total Analysis Systems) [1]. Furthermore, analysis time is reduced diffusion paths are shorter and reactions occur with higher efficiency. Depending on the design and complexity of the microstructures, such fluidic systems can provide all necessary functions as well as to identify or quantify specific pathogens. These functions include cell handling, sample mixing [2], sorting [3], transport and measurement of biomolecules [4]. IMSAS develops multichannel microfluidic systems (see figure 1) by using the negative photoresist SU-8. With this photoresist, microstructures up to 2mm of thickness and aspect ratios up to 20 can be constructed [5]. Besides, the SU-8 is a favourable material for fabrication of microchannels because of its excellent chemical stability against several acids and bases and its thermal stability. These properties make SU-8 a very attractive material for a wide range of applications like micro optics, micro machining, packaging and analytical microfluidic applications, as described in this paper. Figure 1: Picture showing one of several microfluidic devices which have been developed and fabricated at IMSAS. It is a microchannel with integrated columns. This paper presents a method for the fabrication of microchannels, which are composed completely of SU-8 for biological applications. The microstructures were fabricated by using a soft lithography process, which involves the negative resist and utilizes SU-8 itself as adhesive bonding, under low temperatures. B3.3 SENSOR+TEST Conference 2009 SENSOR 2009 Proceedings I 193 Borosilicate glass and silicon were selected as substrate material, because processing techniques of the silicon are well developed and SU-8 provides good adhesion to both materials.