Design and construction of a micromilled fluidic device as part of a DNA biosensor

Under the Optonanogen project (EU contract IST-2001-37239), a novel biosensor has been developed, which incorporates a disposable acrylic polymethylmethacrylate (PMMA) fluidic header. This header is designed to deliver a sample to a series of chemically primed cantilevers where hybridization of target DNA sequences and resulting deflection of the cantilevers is detected optically. Two different microfluidic headers are described, which are designed to incorporate the cantilever chip and which demonstrate a novel approach to microfluidic header assembly, integration with macroscale fluidics, fluidic handling, and priming strategies. The first header facilitates the delivery of a single fluid sample to all cantilevers, whereas the second permits discrete delivery of samples to isolated cantilevers, despite all cantilevers being contained on a single chip. This second, multi-path header therefore allows simultaneous analysis of multiple samples, or multiple parallel tests on a single sample. This paper describes these headers and for the multi-path device details the design changes incorporated to ensure effective isolation of the sample including a novel valve to improve priming of the microfluidic circuit.