Fabrication of an hybrid plastic-silicon microfluidic device for high-throughput genotyping

The lab-on-a-chip approach has been increasingly present in biological research over the last ten years, high-throughput analyses being one of the promising utilization. This work presents a development of an automated genotyping system based on a continuous flow analysis which integrates all the steps of the genotyping process (PCR Polymerase Chain Reaction. purification and sequencing). The genotyping device consists of a disposable hybrid silicon-plastic microfluidic chip.. equipped with a permanent external, heating/cooling system.. syringe-pumps based injection systems and on-line fluorescence detection. High throughput is obtained by performing the reaction in a continuous flow (1 reaction every 6min per channel) and in parallel (48 channels). The technical solutions developed to fabricate the hybrid silicon-plastic microfluidic device are presented here. It includes a polycarbonate substrate having 48 parallel grooves sealed by film lamination techniques to create the channels. Two different solutions for the sealing of the channels are compared in relation to their biocompatibility, fluidic behavior and fabrication process yield. Surface roughness of the channels is a key point. Silicon fluidic chips are used for thermo-cycled reactions. A specific technique has been developed to bond silicon chips onto the plastic part which ensures alignment and hermetic fluidic connexion. Surface coatings are studied to enhance the PCR biocompatibility and fluidic behavior of the two-phase liquid flow. We have demonstrated continuous operation over more than 20 hours of the component and validated PCR protocol on microliter samples in a continuous flow reaction.