An All-in-One Microfluidic Device for Blood Plasma Separation and Fluorescence Detection of Cocaine in Whole Blood

Blood drug testing can provide real-time data to assess the recent consumption of illicit drugs. Microfluidic devices have great promise in rapid finger-prick blood tests at point-of-care settings. However, the fabrication of an integrated microfluidic device for whole blood testing remains a challenge because the separation performance is sensitive to modification in downstream product microchambers. In this work, a hydrodynamic force-based blood plasma separation unit has been developed to regulate the blood plasma separation efficiency and yield after it is integrated with the waste outlet, the connection, and detection zones in a microfluidic device. After the plasma is separated from blood by this microfluidic separation unit, it is driven to an aptamer-based detection zone downstream. As a result, this integrated fluorescence microfluidic device can directly detect the cocaine metabolite, benzoylecgonine (BEC), in a drop of whole blood sample with readout by a hand-held fluorescence reader, achieving a limit of detection (LOD) of 0.62 μg/mL. This integrated all-in-one microfluidic device can serve as a general detection platform for the measurement of various analytes in finger-prick whole blood samples.