Development of an integrated microfluidic instrument for unattended water-monitoring applications

Field-deployable detection technologies in the nation's water supplies have become a high priority in recent years. The unattended water sensor is presented which employs microfluidic chip-based gel electrophoresis for monitoring proteinaceous analytes in a small integrated sensor platform. The instrument collects samples directly from a domestic water flow. The sample is then processed in an automated microfluidic module using in-house designed fittings, microfluidic pumps and valves prior to analysis via Sandia's microChemLab module, which couples chip-based electrophoresis separations with sensitive LIF detection. The system is controlled using LabVIEW software to analyze water samples about every 12 min. The sample preparation, detection and data analysis has all been fully automated. Pressure transducers and a positive control verify correct operation of the system, remotely. A two-color LIF detector with internal standards allows corrections to migration time to account for ambient temperature changes. The initial unattended water sensor prototype is configured to detect protein biotoxins such as ricin as a first step toward a total bioanalysis capability based on protein profiling. The system has undergone significant testing at two water utilities. The design and optimization of the sample preparation train is presented with results from both laboratory and field testing.