Human blood microfluidic test chip for imaging, label-free biosensor

We designed and evaluated a microfluidic test chip for human blood filtration and imaging label-free detection of multiple biomarkers. The microfluidic chip has a total size of 75 mm × 25 mm × 2 mm. It is realized as an assembly of a plastic chip and a functionalized photonic crystal slab on a glass substrate. The plastic chip contains capillary channels, a filter membrane and a cavity open on one side. The photonic crystal chip is bonded with an adhesive foil to the open cavity. Human blood filtration is demonstrated. We determined that fluorescently labelled particles of diameter 3 µm or larger are filtered out by the system. Refractometric measurements are performed with the test chip in combination with a compact imaging read-out system to investigate the system response to refractive index changes. Flow dynamics in the sensor cavity are imaged for replacing water by isopropanol. Finally, the binding of 500 nm biotin dissolved in phosphate buffer saline to a photonic crystal surface locally functionalized with streptavidin is demonstrated.