Micro-electro-mechanical systems are now used in a wide variety of applications ranging from biodetection to the healthcare industry. Electrokinetic techniques such as dielectrophoresis and electroosmosis are frequently used for the manipulation of cells, molecules, and spores. In this paper, we show that dielectrophoresis can be used to manipulate allergens and bacteria in a wide variety of microfiuidic devices. We have found that allergens such as Penicillium brevicompactum dembnstrate positive dielectrophoresis and moves toward high field gradient regions while the non-biological latex beads move towards the low electric field gradient regions. Microfiuidic devices equipped with dielectrophoretic gates arranged perpendicular to the flow were designed and fabricated at Sandia National Laboratories. Experiments were conducted on flowing suspensions over a broad range of flow and electric field parameters to investigate how these characteristics affect the concentration and separation of particles. Trapping using the dielectrophoretic gating device as well as the design, experimental results, and analysis of devices for particle filtration are presented. Some of the devices were fabricated using Sandia's (SwIFT ~TM) process while other devices were fabricated using polymers and traditional photolithography methods. We present both methods used in the fabrication of devices. The long-term goal is to develop complete hand held Lab-on-a-Chip microsystems for biodetection.
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