A novel method for fabricating microfluidic devices containing immobilized biological specimens

Abstract

Microfluidic devices are dominantly fabricated using the soft lithography microfabrication techniques and polydimethylsiloxane (PDMS) as a structural material. Although the technique is applicable for the majority of microfluidic devices, it has limited use for the fabrication of microfluidic devices with immobilized biological specimen due to the low biocompatibility - a consequence of the plasma-assisted bonding step during the assembly of the final device. In this step, biological specimens within the microfluidic device are affected by strong plasma exposure which ultimately can degrade their biochemical activity and stability. To the best of our knowledge, this paper presents for the first time a method for increasing the biocompatibility of a conventional PDMS soft lithography process and enables fabrication of the microfluidic devices containing immobilized biological specimens. Protection of the biological specimen during the plasma bonding step is ensured by placing a protective Polyvinyl Alcohol (PVA) nanofiber layer over the biological specimens. The method is verified against the conventional soft lithography method by fabricating microfluidic devices containing enzyme-filled microreactors and following enzymatic reactions. It was shown that inadvantageous impact of the plasma is reduced by utilizing a protective PVA layer which ultimately preserves the specific activity and biochemical stability of the immobilized enzymes.